J. Med. Chem. 2000, 43. 1257-1263
`
`1257
`
`Expedited Articles
`
`TN-3-Substituted Imidazoquinazolinones: Potent and Selective PDE5 Inhibitors
`as Potential Agents for Treatment of Erectile Dysfunction
`
`fDavid P. Rotella,‘-' Zhong Sun,’ Yeheng Zhu,i John Krupinskif Ronald Pongrac," Laurie Scliger,’
`.Diane Normandin,‘ and John E. Macor
`Discovery Chentistry and Cardiovascular Drug Discovery, Bristol-Myers Squibb Pharmaceutical Research Institute,
`PO. Box 5400, Princeton. New Jersey 08543-5400
`
`Received February 23. 2000
`
`Phosphodiesterase type 5 (PDE5) inhibitors with improved PDE isozyme selectivity relative
`to sildenafil may result in agents for the treatment of male erectile dysfunction (MED) with 8.
`lower incidence of PDE-associated adverse efl'ects. This paper describes the discovery of 14, a
`PDE5 inhibitor with improved potency and selectivity in vitro compared to sildenafil. This
`compound shows activity in a functional assay of erectile function comparable to that of
`sildenafil.
`
`Chart 1
`
`.g:
`
`(‘N
`H3C’N‘)
`
`1
`clldcnafll (Viagra®)
`
`~
`
`H3610
`
`cu,
`0
`HM
`
`\
`N
`O/\CH;,
`
`can
`
`0
`HNJIN‘N
`\N N,
`H
`
`2
`zaprlnact
`
`”°
`
`0
`
`\HN
`(E/k"
`
`3
`
`IZ\é2
`
`(Chart 1) as a moderately active but nonselective lead
`(Table 1). The potency of compound 3 was improved 10-
`fold by incorporation of an N-methylpiperazinesulfonw
`mide in the pendant alkoxybenzene ring, leading to
`compound 7 (Scheme 1). This SAR observation was
`analogous to that described by Terrett et al.‘'’ in the
`development of sildenafil. While this improved activity
`was encouraging, it was apparent that this modification
`did not enhance isozyme selectivity compared to sildena-
`fil (Table 1).
`In an attempt to improve the potency and selectivity
`of this series, modification of the imidazole ring was
`investigated. The synthesis of an N-3-benzyl derivative
`of 7 was carried out as shown in Scheme 2. Key to the
`synthesis of 11 was the selective formation of the
`imidazole ring in 9 that did not also lead to quinazoli-
`none formation. This was achieved by stirring the
`diamine intennediate derived from 8 in formic acid
`overnight at room temperature. The formyl group on
`the amine orlho to the primary amide which also
`resulted from this transformation was cleaved by brief
`10.102lljm00008l+ CCC: $19.00 © 2000 American Chemical Society
`Published on Web 03/18/2000
`
`Introduction
`The utility of sildenafil (1, Viagra; Chart 1) as an
`ofiicacious, orally active agent for the treatment of male
`erectile dysfunction (MED)' has created significant
`interest in the discovery of additional phosphodiesterase
`type 5 (PDE5) inhibitors.’ PDE5 is the primary cGMP-
`hydrolyzing enzyme activity present
`in the corpus
`eavemosum, the smooth muscle in the penis which helps
`control vascular tone. When a man is sexually stimu-
`lated, nitric oxide is released from the cavernosal nerve.
`This activates soluble guanylyl cyclase in the corpus
`cavemosum, causing an increase in intracellular cGMP,
`which is normally hydrolyzed by PDE5. Inhibition of
`PDE5 elevates levels of the cyclic nucleotide, leading
`to enhanced relaxation of smooth muscle, increased
`arterial inflow, venous congestion, and ultimately an
`erection. Despite the eflicacy of 1 as a treatment for
`MED, there are notable drawbacks associated with its
`use. Clinically significant adverse effects such as nau-
`sea, headache, cutaneous flushing, and visual distur-
`bances have been noted, and their incidence is dose-
`dependent. Certain of these are thought to be due to
`nonspecific inhibition of other PDE5, specifically PDE1
`and PDE6."v‘ Thus, the identification ofpotent and more
`selective PDE5 inhibitors is of primary interest. This
`paper describes the discovery of an N-3-(fluorobenzyl)-
`vimidazoquinanolinone that is more potent and selective
`in vitro as a PDE5 inhibitor compared to sildenafil. This
`compound demonstrates activity comparable to I in a
`functional assay of erectile dysfunction using rabbit
`corpus cavemosum tissue strips.
`Results and Discussion
`
`Using the prototypical PDE5 inhibitor zaprinast (2;
`Chart 1)‘ as a template, directed screening identified 3
`‘Corresponding author David P. Rolella. Phone: 609-818-5398.
`Fax: 609-818-3450. E-mail: david.rote1la@bms.cnm.
`‘ Discovery Chemistry.
`' Cardiovascular Drug Discovery.
`
`
`
`Page 1 of 7
`
`Astraleneca Exhibit 2254
`
`Mylan v. Astraleneca
`IPR2015—01340
`
`

`
`1253 Journal ofMedicinul Chemistry, 2000, Vol. 43, No. 7
`
`
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`
`
`Table 1. PDE5 IC,=,u and Selectivity Ratios for Other PDEs“
`
`
`
`
`
`
`
`
`
`
`
`
`PDE5
`lcsn ratio
`
`compd IC5g{nM)° PDE1/5 PDE2/5 PDE3/5 PDE4-1'5 PDEW5
`
`
`
`
`
`
`
`1.6 :1: 0.5
`2600
`1
`140
`> 104
`3500
`8
`
`
`
`
`
`
`
`
`
`44 :: 19
`100
`200
`3
`360
`300
`1
`
`
`
`
`
`
`
`
`2
`5.3 :l: 0.6
`1600
`90
`7
`1300
`5900
`
`
`
`
`
`
`
`
`
`600
`5.3 :l: 1.1
`20
`11
`3400
`> 10‘
`8800
`
`
`
`
`
`
`
`
`
`0.48 :l: 0.1
`60
`14
`4200
`>105
`>105
`>105
`
`
`
`
`
`
`
`
`
`" Enzyme sources: PDE1, bovine heart; PDE2, rat kidney;
`
`
`
`
`
`
`
`
`
`PDE3, human platelet; PDE4, rat kidney; PDE5, human platelet;
`
`
`
`
`
`
`
`
`
`PDE6, bovine retina. 5 All lC5o determinations are averages based
`
`
`
`
`
`
`
`
`
`on 3 determinations; PDE5 values are represented as IC5e 1 SD
`
`
`
`
`
`
`
`
`
`
`
`for at least 3 independent experiments.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`treatment with acid, leading to 9 in good overall yield
`
`
`
`
`
`
`
`
`
`from dinitro intermediate 3. Acylation of the aniline
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`with acid chloride 12 gave piperazine 10, which without
`purification was cyclized using potassium tert-butoxide
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`in refluxing tert-butyl alcohol to furnish 11. In vitro, 11
`
`
`
`
`
`
`
`maintained PDE5 potency (relative to 7) and also
`substantially improved the selectivity profile of the
`
`
`
`
`
`
`series (Table 1). Specifically, 11 was 20-fold selective
`
`
`
`
`
`
`
`for PDE6, 3400-fold selective for PDE1, and 600-fold
`
`
`
`
`
`
`
`selective for PDE4.
`
`
`
`
`
`
`
`
`
`
`
`
`
`Compounds 7 and 11 were compared to 1 in a
`secondary in vitro assay to evaluate their functional
`
`
`
`
`
`
`
`
`effects on smooth muscle relaxation in rabbit cavernosal
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`tissue st;r'ips.“=7 This model measures potentiation of the
`normal smooth muscle relaxation process and reflects
`
`
`
`
`
`
`
`the indirect effect that a PDE5 inhibitor exerts on the
`
`
`
`
`
`
`
`
`
`target tissue. It is important to note that administration
`
`
`
`
`
`
`
`
`
`of sildenafil does not directly result in an erection (vide
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`supra), rather an external stimulus is required to
`initiate the cascade. The data in Table 2 indicate that
`
`
`
`
`
`
`
`
`
`
`the unsubstituted benzimidazole 7 exhibited a dose-
`
`
`
`
`
`
`related effect and was as efficacious as sildenafil as
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`measured by the potentiation of relaxation enhance-
`
`
`
`
`
`
`
`
`
`ment. The N-3-benzyl derivative 11 was less active than
`
`
`
`
`
`
`
`
`
`both 1 and 7. We speculated that a contributing factor
`
`
`
`
`
`
`
`
`to this reduced activity was the significantly higher
`
`
`
`
`
`
`
`
`
`molecular weight of 11 (MW Z 572), compared to either
`
`
`
`
`
`
`
`
`
`
`1 (MW = 474) or 7 [MW = 482}. This may reduce
`
`
`diffusion of the compound into smooth muscle cells of
`
`
`
`
`
`
`
`
`
`the corpus cavernosurn where the drug must act.
`
`
`
`
`
`
`
`
`Carboxamides offer an alternative, lower molecular
`
`
`
`
`
`
`
`
`
`
`
`
`weight handle for incorporation of potency-enhancing
`
`
`
`
`
`
`substituents in the alkoxybenzene moiety? Making use
`
`
`
`
`
`
`
`
`
`of this variation, along with further optimization of the
`
`
`
`
`
`
`
`
`N-3-benzyl suhstituent, led to the synthesis ofcompound
`
`
`
`
`
`
`
`
`14 {Scheme 3). Benzimidazole 9b was coupled with
`
`
`
`
`
`4-bromo-2-propoxybenzoic acid to ll.1l'I11Sl1 an intermedi-
`
`
`
`
`
`
`
`
`
`ate amide, which was cyclized to afford 13. Cyanide
`
`
`
`
`
`
`substitution, hydrolysis to the corresponding carboxylic
`
`
`
`
`
`
`
`
`
`acid, and amide formation afforded 14 in good yield.
`Amide 14 displayed enhanced PDE5 potency (IC5o =
`
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`
`
`
`
`
`
`
`
`
`
`0.48 nM), compared to sildenafil and further improved
`
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`
`
`
`
`
`
`
`
`the PDE selectivity profile of 11 (Table 1). Significant
`
`
`
`
`
`
`
`
`
`
`inhibition (PDE lC5{} < 1 ,uM} of other PDEs is limited
`to PDE6. In this instance, compound 14 was 60-fold
`
`
`
`
`
`
`
`
`
`selective for PDE5, compared to less than 10-fold
`
`
`
`
`
`
`
`
`selective for sildenafil. Note that the improved selectiv-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`ity of 14 can be attributed to both an increase in PDE5
`
`
`
`
`
`
`
`
`potency and a decrease in affinity for PDE6 (Table 1).
`
`Evaluation of 14 (MW = 4'72) in rabbit corpus caver-
`
`
`
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`
`
`
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`
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`nosum tissue clearly showed a positive dose-related
`
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`Retails oi oi.
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`effect and improved efficacy compared to the higher
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`molecular weight sulfonamide 11. Compound 14 proved
`
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`to be similar in efficacy to both 1 and 7 as measured by
`
`
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`
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`
`
`
`the increase in the relaxation integral relative to the
`control (Table 2). This information suggests that 14 is
`
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`
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`
`
`better able to penetrate cells in the target
`tissue,
`
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`compared to 11, but also shows that the improved in
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`vitro potency relative to sildenafil did not lead to a
`
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`
`
`measurable increase in functional efficacy. Neverthe-
`less, the data in Table 2 indicate that this group ofN-3-
`
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`benzylbenzimidazoles is worthy of further study as
`
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`potential agents for the treatment of MED.
`Concluion
`
`
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`In summary, we have identified a quinazolinone
`
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`
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`template that provides potent PDE5 inhibitors. Addition
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`of a benzyl moiety at N-3 of this template confers
`
`
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`substantial improvement in PDE selectivity and potency
`
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`
`
`
`compared to sildenafil. This improved selectivity should
`
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`
`
`translate into an improved PDE-related side effect
`
`
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`
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`profile in vivo, based on experience to date with sildena-
`
`fil. In a functional assay of erectile function, the more
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`selective PDE5 inhibitor 14 demonstrated activity com-
`
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`parable to sildenafil based on the ability of the com-
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`pound to relax rabbit corpus cavernosurn tissue. Addi-
`tional studies with this series of molecules will be
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`reported in due course.
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`
`Experimental Section
`General. NMR spectra were obtained at 400 MHz (H) and
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`100 MHZ ('30) on a Varian DRX-400 spectrometer. Chemical
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`shifts are reported in ppm downfield from TMS as an internal
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`standard. Thin—layer chromatography was carried out using
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`2.5 x 7.5-cm silica gel 60 (250 ,uM layer) plates with UV
`
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`detection. Magnesium sulfate was employed to dry organic
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`extracts prior to concentration by rotary evaporation. Flash
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`chromatography was done using EM Science silica gel 60
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`(230—400 mesh). Standard solvents from EM Science were
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`used as received. Anhydrous solvents from EM Science or
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`Aldrich and all other commercially available reagents were
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`used without further purification. Melting points were taken
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`using a Thomas-Hoover MelTemp apparatus. Microanalysis
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`was carried out by the Analytical Chemistry department at
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`Bristol-Myers Squibb. Preparative HPLC was carried out on
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`a Shimadzu LCSA system using a YMC ODS-A 30 x 250-mm
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`column eluting with a 30-min linear gradient from 90% solvent
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`A to 90% solvent B (solvent A: 90% water/10% MeOl-I with
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`0.1% TFA, solvent B: 90% MeOHll0% water with 0.1% TFA).
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`Low-resolution mass spectra were recorded using an LC—MS
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`system consisting of a Micromass ZMD mass spectrometer in
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`electrospray (M + H) mode and a Shimadzu LCIDAT HPLC
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`using a YMC ODS-A 3 x 50-mm column using the same
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`solvents as noted above in a 2-min linear gradient.
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`2-Amino-4-chloro-5-nitrobenzamide (4). 4-Chloroam
`
`
`thranilic acid (10.0 g, 56.5 mmol) was dissolved at room
`
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`temperature with stirring in 190 mL of distilled Water
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`containing 8.98 g (84.7 mmol) Na2CO3. When the 4-chloroan-
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`thranilic acid was completely dissolved, at 20% w/v solution of"
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`phosgene in toluene (84 1:oL) was added dropwise via a
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`dropping Funnel over 4.5 min. The resulting suspension was
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`stirred at room temperature overnight under nitrogen. The
`
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`product was collected by filtration and washed well with water.
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`The resulting gray-white solid was dried in a vacuum oven at
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`60 "C overnight to provide 7-chloro-1,4-dihydro-2H-3,1-ben-
`
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`
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`zoxazine-2,4-dione (10.3 g, 52.3 mmol, 93%): ‘H NMR (DMSO—
`
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`
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`da) 5 11.93 (br s, 1H), 7.17 (d. J = 1.5 Hz, 1H), 7.28 (dd, J=
`
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`1.5 and 3.2 Hz, 1H}, 7.91(d, J = 8.2 Hz, IH).
`
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`A portion of this material (5.1 g, 25.9 mmol) was added in
`
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`portions over 40 min to a cold (0 °C] solution of concentrated
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`(96—98%) sulfuric acid (15 mL) and concentrated (70%) nitric
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`Page 2 of 7
`
`

`
`
`.-Substituted Imidazoquinazolinorm
`Journal ofMedicinal Chemistry, 2000, Vol. 43, No. 7 1259
`
`0
`
`/<jE°°'" s.b.c
`
`NH,
`
`CI
`
`
`
`°?"m:°°N"‘2 6.0
`
`(:1
`
`Mn,
`
`is
`
`0
`
`O N
`
`Cl
`
`2 H 3
`
`/\,CH
`
`N
`
`5
`
`O
`
`O2 HN N% 9' H‘ i
`,
`j. I/\N,S
`\N
`cl
`/\/CH3
`Hsc/Nx)
`
`6
`
`
`
`02 HN N$
`NH
`(\N,s
`\N
`/\/CH3
`H36"\)
`
`7
`
`' ls) Phoegene/PhCH;/sq Nsg00;, rt 18 h, 93%; (b) HN0;/H2804, 0 ‘C 1 h, 49%; (c) l-l0Ac, NH4OAc. 100 “C 3 h. 86%; (d) 2-prupoxybenzoyl
`»chloride/DMF/pyridine. 80 °C 2.6 h. 93%; (e) NaOH/H202, sq EtOH, reflux 2 h, 89%; (D (i) chlorosulfonic acid, 0 “C to rt 4 h, (ii)
`4-methylpiperszine, CHgCl9, rt 2 h. 85%; (g) 2 M NH;/EtOH, sealed tube, 130 °C overnight, 72%; (h) 40 psi H2, EtOH/sq HCl. 10% Pd-C.
`It overnight. 59%; (i) formic acid. reflux 3 h, 93%.
`
`Scheme 2"
`
`x
`
`«"
`
`on
`
`2:.
`
`._ blc
`
`©W
` mNH2 d
`
`N02
`
`as Knit
`3 X.-F
`
`To
`
`X01
`<N CONHz
`
`\
`
`N
`
`NH,
`
`Is X-H
`b X.-F
`
`4.
`
`10 0
`
`Qx
`
`/\/C“: _.,
`
`N—CHa
`
`0:
`
`OH
`00zCHa
`
`cs):
`0
`(‘N’ U V‘cH,
`H3C’N\)
`cool
`
`12
`
`;°”°
`
`f‘N—so,
`"‘3c'N\/I
`11
`
`' (s) H3804/KN0g. 40-146 °C, 45%; (b) (i) (COCl);. CH-JCI2, cat. DMF. 1 h, (ii) NH40l-I. acetone. 0 “C 45 min, 75%; (c) (X)-benzylnmine,
`THY, EtgN, reflux 1-2 h. 81-84%; (C) (i) 25 psi H2, PtO2, MQOH, 3-5 h; (ii) formic acid, rt overnight. (iii) 10% sq HCI/Et.0H, rt. 3 h,
`W-93%; (e) 5-[(4-methylpiperszinyl)aulfonyl]-2-propoxybenzayl chloride, pyridine/DMF. 76 ‘C 1-2 h; (D tBu0l(-tBu0H, reflux 2 h,
`3% (two steps); (g) propyl iodide, KgCO;/DMF, rt overnight; (h) HS03Cl/SOCla, 0 °C 30 min. 28% net; (i) 4-rnethylpipemzine. triethylamine.
`Cflzclz. 0 °c 1.6 h. 100%; (j) Li0H, Tl-ll-‘—l-I20, reflux 16 h, 96%; no «cocm, CHzClz. cat. DMF. 2 h.
`
`Table 2. Rabbit Corpus Csvsrnoeum Functional Assay
`
`This product (6.5 g. 26.8 mmol) was suspended in glacial
`acetic acid (70 mL). Ammonium acetate (6.2 g. 80.6 mmol) was
` added, and the resulting mixture was heated w mo °c with
`30 HM‘
`300 IIM“
`stirring for 3 h. Afler cooling to room temperature, the brown
`150 i 20
`220 i 25
`solution was poured into distilled water (200 mL) to precipitate
`140 3; 10
`210 1 30
`a yellow solid which was collected by filtration and washed
`120 i 10
`150 1 13
`well with water and ether. This material was first air—dried,
`140 1 12
`190 :k 32
`then dried overnight under high vacuum to provide 4 (4.9 g,
`23.0 mmol. 86%):
`‘H NMR (DMSO-dc) 6 6.92 (s. 1H). 7.49 (br
`3, 1H), 7.39 (br s, 2H), 8.22 (br 3, 11-1), 3.53 (s, 1m.
`7-Chlaro-8-nitro-2-(2-pmpoxyphenyl)-4(8H)-quinazolb
`none (5). Compound 4 (3.50 g, 16.3 mmol) was dissolved in
`pyridine ntroom temperature(l mol equiv). o—Propoxybenzoy|
`chloride (4.51 g, 22.8 mmol) was partially dissolved in a small
`quantity (<10 mL) of DMF. and this mixture was added to
`the pyridine solution. The resulting brown solution was heated
`to 80 °C for 2.5 h. The reaction mixture was cooled to room
`temperature and poured into distilled water to precipitate a
`
`°0mPd
`1
`7
`11
`14
`
`_
`' °°""°' ‘“““““‘“ "°‘P°"'° ‘ ‘°°'*-
`acid (15 mL). The reaction was stirred at 0 °C for 1 h, then
`filtered through a sintered glass funnel. The filtrate was
`cautiously poured into crushed ice (250 g) to precipitate a
`yellow-tan solid. This solid was washed well with water and
`dried overnight in a vacuum oven (60 °C) to fumish 7-chloro-
`1,4-dihydro-6-nitro-2H-3.1-benzoxazine-2,4-dione (3.09 g. 12.7
`mmol, 49%):
`‘H NMR (DMSO-dg) 6 12.30 (hr 3, 1H), 7.28 (s,
`1H), 8.53 (s, 1H).
`
`Page 3 of 7
`
`

`
`1260 Journal ofMed£cz'nal Chemistry, 2000, Vol. 43. No. 7
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`
`Rotella et at
`
`
`
`
`
`Scheme 3"
`
`
`
`
`9b
`
`.1)
`
`N
`
`o
`F
`
`” NH 0
`
`/
`
`3
`<‘N
`
`
`13
`
`
`0
`fcHa R0‘
`
`die
`<\ flH G
`
`
`N
`
`N
`
`Nr
`
`14
`
`
`
`C.
`T.
`
`
`
`B!
`
`J/CH3
`
`
`
`cows;
`
`(C1 CuCN,
`tBuOH, reflux 2 h, 82%;
`" fa} 2-Propoxy-4-bromobenzoic acid, HOBt. EDAC, cat. DMAP, DMF, 4 h; (b) tBuOK,
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`N—methylpyr1'olidinone, reflux 18 h, 91%; Ed) NaOH. Et0H. reflux 5 h, 75%; (e) NH;/THF, EDAC, 1-lOBt, cat, DMAP, pyridine, 82%.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
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`brown solid. This suspension was stirred at room temperature
`
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`
`
`
`
`
`
`overnight. In the morning, the solid was collected by filtration
`
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`
`
`
`
`
`
`
`
`and washed with water, 10% HCl, and then ether. The product
`
`
`
`
`
`
`
`
`
`
`
`(4-chloro—2-[( 2~propoxy‘benzoyl lamina]-5-nitrobenzamide) was
`
`
`obtained in 93% yield (5.70 g, 15.2 mrnoll after drying in a
`
`
`
`
`
`
`
`
`
`
`
`
`
`vacuum oven: mp 177-178 ‘'0', ‘H NM"R (DMSO-d5} d 9.04 {s,
`
`
`
`
`
`
`
`
`
`1H), 8.55 (s, 2H), 8.05 (s, 1H), 7.88 (d. J = 6.5 HZ. 1H), 7.59
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`(apparent t, J = 6.2 Hz, 1H), 7.23 (d, J = 6.5 Hz, 1H), 7.10
`
`
`
`
`
`
`
`
`
`
`
`
`
`(apparent t, J = 8.2 Hz, 11-1), 4.19 (t, J = 7.2 Hz, 2H], 1.84 (m,
`
`
`
`
`
`
`
`
`
`
`
`
`
`2H), 0.92 (!:, J = 7.4 Hz, 3H).
`
`
`
`
`
`
`
`This material was suspended in absolute ethanol (15 mL
`
`
`
`
`
`
`
`
`
`ethanol), and water was added (7 1211.). Sodium hydroxide (0.73
`
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`
`
`
`
`
`
`g, 18.2 mmol) was then added, followed by 0.86 mL (0.26 g,
`
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`
`
`
`
`
`
`7.6 mmol) of 30% twfvl aqueous hydrogen peroxide. The
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`
`
`reaction mixture was then heated to reflux, and the starting
`
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`
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`material gradually dissolved. When the starting material was
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`
`
`
`
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`consumed as determined by TLC analysis (generally in less
`
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`
`
`
`
`
`
`than 2 h), the reaction was cooled to room temperature and
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`
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`
`
`
`
`
`
`concentrated by rotary evaporation to furnish a yellow-brown
`
`
`
`
`
`
`
`solid which was washed with water and triturated with ether
`
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`
`
`
`
`
`
`
`
`to provide an 89% yield (4.38 g, 12.2 mmol) o{'5: mp 178- 181
`
`
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`
`
`
`
`
`
`
`
`
`
`
`‘U; ‘H NMR (DMSO-d;,-] r3 8.80 (s, 1H), 8.59 (apparent cl, J =-
`
`
`
`
`
`
`
`
`
`
`
`8 Hz, 1H}, 7.91 (s, 1H), 7.57 (apparent t, J = 8 Hz, 1H), 7.19
`
`
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`
`
`
`
`
`
`
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`(apparent t, J = 7.4 Hz, 1H), 7.09 (d, J = 8 Hz, 1H), 4.24 (t, J
`
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`
`
`
`
`
`
`
`
`
`= 6.5 Hz, 2H}, 2.04 (ni, 2H), 1.18 (t, J I 7.4 Hz, 3H),
`
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`
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`
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`
`
`I -{I3-( 7-Chloro-3,4-dihydro-0-nitro-4-oxo-2-quinazoli
`nyl)1J1'npox;y]Jl1enyl]s1.Ilfonyl]-4-methylpiperazine (0). Chlo-
`
`
`
`rosulfonic acid (10 mLl was oooled to 0 “C in ice under nitrogen.
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`Compound 5 (0.81 g, 2.3 mmol) was added portionwise over
`
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`
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`20-30 min. The reaction was stirred at 0 °C for 5 h then, very
`
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`
`
`
`
`
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`cautiously. poured slowly into crushed ice. The resuiting yellow
`
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`
`
`
`
`
`
`precipitate was collected by filtration, washed thoroughly with
`
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`
`
`
`
`
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`water and sucked dry with a water aspirator. This material
`
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`
`
`
`
`
`
`
`was used without further purification for sulfonamide forma-
`
`
`
`
`
`
`
`tion. The resulting sulfonyl chloride was partially dissolved
`
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`
`
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`in 20 mL of methylene chloride.:'2 mL of THF. Triethylamine
`
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`
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`(0.31 g, 3.04 mmol, 423 ,uLi was added. This was followed by
`
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`0.24 g‘ (264 p'L, 2.39 mmo1}of4-methylpiperazine. The reaction
`
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`
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`mixture was stirred at room temperature for 2 h then diluted
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`with additional methylene chloride and washed twice with
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`water, dried over magnesium sulfate and concentrated to
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`furnish the product as a yellow solid in 72% yield (0.86 g, 1.66
`
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`
`
`
`
`mmol): mp 225~228 °C; LRMS [MH+l 522; ‘H NMR (CDCl3)
`
`
`
`
`
`
`
`
`
`
`
`(5 8.94 (d, 1H, J = 2.4 Hz), 8.79 (S, 1H), 7.98 (s, 1H); 7.92 (dd,
`
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`1H, J = 2.4, 8.7 Hz), 7.22 1d, 1 H, J = 8.7 Hz), 4.32 (t, 2H, J
`
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`
`
`
`
`
`
`
`
`
`
`
`
`
`= 6.6 Hz). 3.08-3.12 (m, 4H], 2.43-2.56 (m, 4H}, 2.28 (s, 3H),
`
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`
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`2.05-2.10 (m, 2H), 1.40 (t, 2!-1, J 2 7.2 Hz), 1.19 (t, 3H, J =
`
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`7.2 Hz).
`
`
`1-[[3-(7,8-Dihydro-8-oxo-1H-imidazo[4,5-g]quinazolin-
`
`
`
`
`6-yl)-4-propoiqrphenyl]snlfonyll-4-methylpiperazine (7).
`
`
`Compound 6 (0.65 g. 1.24 mmol) was suspended in equal
`
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`volumes of absolute ethanol and 28% aqueous ammonium
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`hydroxide in a pressure bottle (total volume 25 mLl with a
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`stirring bar. After the bottled was tightly sealed. the contents
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`were heated at 140 °C overnight. The reaction mixture was
`
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`cooled to room temperature. and the resulting suspension was
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`diluted with water. The resulting mixture was filtered to afford
`
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`a bright yellow solid. This solid was washed with water,
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`ethanol, and ether to provide 1-[[3-(7-amino-3,4-dihydro-6-
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`
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`nitro-4-oxo-2-quinazolinyl)-4~propoxyphenyllsulfonyl]—4—meth-
`ylpiperazine (0.44 g, 0.87 mmol, 70% yield); mp 270-271 “C;
`
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`LRMS [MH"] 503; ‘H NMR (DMSO-dc.) rl 8.75 (5, 1H), 7.94 (d,
`
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`1H, J = 2.3 Hz), 7.86 (dd, 1h, J = 2.3, 8.6 Hz), 7.72 (s, 1H"),
`
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`7.41(d,1H, J = 8.7 Hz}, 7.12 (s, 1H), 4.13 (t, 2H, J = 6.2 Hz],
`
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`2.90 (br s, 4H), 2.37 (br s, 4H), 2.15 (s, 31-1), 1.71- 1.77 (m, 2H),
`
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`0.95 (t, 3H. J = 6.2 HZ).
`
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`This material was partially dissolved in 5 mL of 10%
`
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`aqueous HCl and added to a suspension of 10% palladium on
`
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`charcoal (50 wt %) in absolute ethanol (20 ml.) in a Parr bottle.
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`The mixture was hydrogenated on a Parr shaker at room
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`temperature under 40 psi H2 overnight. The suspension was
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`filtered through Celite and the cake washed well with ethanol.
`
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`The filtrate was evaporated to provide 1-[[3-(6,7-dia1nino-3,4-
`
`
`
`
`
`
`dihydro-4—oxo—2-quinazolinyl)—4—propoxyphenyl]sulfonyl]-4-me-
`thylpiperazine as the hydrochloride salt (0.21 g, 0.44 mmol,
`
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`
`
`
`
`
`
`50% yield). This material was used without further purifica-
`
`
`
`
`
`
`
`
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`tion: LRMS [MH+] 473; ‘H NMR (CD3OD) d 8.22 (s, 1H), 8.18
`
`
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`
`
`
`
`
`
`
`
`(cl. 1H. J = 8.6 Hz). 8.00 (s, 1H), 7.58 (d. 1H, J I 8.6 Hz), 7.15
`
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`
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`(s, 1H], 4.24 (t, 2H. J = 6.2 Hz), 3.94 (br cl, 4-H, J = 8.2 ['12,
`
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`
`
`D20 exchangeable}, 3.24 (In, 4H1, 2.85r3.05 (m. 7H}, 1.80—
`
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`
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`1.93 (m, 2H), 1.00 (t, 3H, J = 6.2 Hz}.
`
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`This diamine (0.20 g, 0.39 mmoll was dissolved in 10 ml. of
`
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`concentrated formic acid and heated to reflux under nitrogen.
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`The reaction was followed by HPLC, and generally conversion
`
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`to product was complete in 2 h or less. The reaction was cooled
`
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`to room temperature and formic acid was removed in vacuo.
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`Residual water was azeotropically removed with ethanol
`
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`leaving a light brown to reddish brown solid. The solid was
`
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`dissolved in 10% aqueous HCl and washed with three portions
`
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`of ethyl acetate. The pH of the water layer was adjusted to 12
`
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`with sodium hydroxide solution and extracted five times with
`
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`ethyl acetate. The collected organic extracts were washed twice
`
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`with brine, dried and concentrated. Further purification was
`
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`accomplished by dissolving this material in 20 mL of EtOAc,
`
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`which was cooled in ice before HC1 gas was passed through
`
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`the solution to deposit fine tan needles of the hydrochloride
`
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`salt of the product (0.14 g, 0.26 mmol, 66% yield): mp (free
`
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`
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`base) 164-167 °C; LRMS [MH’'] 48.3; ‘H NMR (CD30DJ (5 9.59
`
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`
`
`(s, 1H], 8.66 (s, 1H}, 8.22 (d, 1H, J = 2.4 Hz), 8.17 (s, 1H),
`
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`
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`7.96 (dd. 1H, J = 2.4, 8.7 Hz), 7.40 (d, 1H, J = 8.7 Hz), 4.16 (t,
`
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`2H, J = 6.3 Hz), 3.87 [br d, 2H, J = 12.8 Hz), 3.50 (hr cl, 2H,
`
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`J = 12.8 Hz), 3.1-3.2 (in, partially obscured by Me0H, 2H),
`
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`28-292 (m. 5H), 1.75—1.88 (m, 2H}, 0.95 (t, 3H, J = 7.4 Hz).
`
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`Anal. Calcd for C~;;;H27ClN50..S: C, 53.22; H, 5.24; C}, 6.83; N,
`
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`16.19; S, 6.18. Found: C, 53.20; H, 5.25; Cl, 6.79; N, 16.14.
`
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`2,4-Dinitro-5-chlorobenzoic Acid. 3-Chlorobenzoic acid
`
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`
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`(12.5 g, 80 mmoll was dissolved in 145 mL of concentrated
`
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`
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`
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`sulfuric acid with stirring, while warming to 40 °C. Potassium
`
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`
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`nitrate (8.0 g, 78 mmol) was added in divided portions over
`
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`
`
`
`30 min. The reaction mixture was then warmed to 100 “C and
`
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`
`
`an additional 14 g ofpotassium nitrate was added over 20 min.
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`The reaction mixture was warmed to 145 “C and held at this
`
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`temperature for 15 min. The reaction was cooled to room
`
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`temperature and poured into 1 kg of ice to precipitate a faintly
`
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`
`
`
`
`
`
`yellow solid. This material was collected by filtration and
`
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`
`
`washed with water. The resulting solid was then suspended
`
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`
`
`in 500 mL of distilled water and stirred at room temperature
`
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`
`for 45 min. The undissolved solid was collected by filtration
`
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`
`
`
`
`
`
`
`and dried under high vacuum to obtain 8.9 g (36%) yield of
`
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`
`
`
`
`
`product as a faintly yellow solid:
`‘H NMR (acetone~d5) :5 8.76
`
`
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`
`
`
`
`
`
`(s, 1H), 8.26, (s, IH).
`
`
`
`
`
`2,4-Dinitro-5-chlorobeuzamido. 2,4-Dinitro-5-chloroben-
`
`
`Page 4 of 7
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`

`
`
`Journal of Medicinal Chemistry. 2000. Vol. 43. No. 7 1261
`-3-Substituted lmidazoquinazolinones
`
`zoic acid (7.00 g. 28.4 mmol) was suspended in 40 mL ofthionyl
`chloride containing 3 drops of DMF. The suspension was
`warmed to reflux for 4 h. After cooling to room temperature.
`solvent was removed by rotary evaporation leaving a golden
`yellow liquid. This was diluted with 30 mL of acetone and
`added dropwise over 20 min to a 0 °C solution of 20 mL of
`concentrated ammonium hydroxide. The reaction was stirred
`at 0 °C for 30 min. then poured into 250 g of ice. The yellow
`orange precipitate was collected by filtration and washed well
`with water. The solid was dried first by water aspirator then
`under high vacuum to furnish 5.9 g (24 mmol, 84% yield) of
`product:
`‘H NMR (acetone-do) 4) 8.75 (s. 1H), 8.25 (s, 111); mp
`201-203 “C.
`General Procedure for Preparation of 5-Benzylamino-
`2.4—Dinitro-5-chlombenzarnidc (2.00-
`14.25 mmol) was suspended in 15-70 mL of"I‘l-{F and 1.2 equiv
`of triethylamine was added. followed by 1.2 equiv of the
`appropriate bsnzylamine. The reaction was heated to reflux
`until TLC indicated starting material had been consumed. The
`cooled reaction mixture was filtered and the filtrate was
`concentrated in vacuo leaving a solid which was triturated
`with ether. This solid was collected by filtration. washed with
`ether and dried affording the product.
`5-[(Phenylrr|ethyl)amino]-2,4-dinitrobenzamide (8a):
`95% yield; mp 143-146 "C; ‘H NMR (acetone) 6 9.21 (br s.
`1H), 8.90 (8, 1H), 7.31-7.49 (m, 5H), 7.13 (s, 1H), 7.02 (br s,
`1H). 4.90 (d. 2H. J = 6 Hz).
`5-l I(4-Fluorophenyllrnethyllaminol-2.4—dinitr-obenzm
`rnide (so): 81% yield: mp 178-180 °c; ‘H NMR (mason .5
`9.44 (br t 1H. exchangeable with D-10). 8.72 (s. 1H), 8.35 (br s.
`2H, exchangeable with D20), 7.40-7.44 (in, 21-1), 7.15-7.21
`(tn, 2H), 7.02 (s, 1H), 4.75 (d, 2H. J = 6.3 Hz).
`General Procedure for Synthesis of 5-Amino-1-l(phe-
`nylmethyl)arnino]-III-benaimidazole-8-can-boxarnides. The
`appropriate 5-benzylamino-2,4-dinitrobenzamide (83 or 81)
`from above) (0.50-3.5 g) was partially dissolved in methanol
`(20-200 mL) containing 25 wt % platinum oxide. Hydrogen
`was introduced using a balloon and the flask was evacuated
`and filled several times before leaving the suspension stirring
`under an atmosphere of hydrogen at room temperature. The
`mixture was stirred until HPLC analysis showed consumption
`of starting material and conversion to the desired diamine
`product (typically 5 h). The suspension was filtered through
`Celite and the filter cake was washed with methanol. The
`filtrate was concentrated to furnish the crude diamine. This
`material was then dissolved in concentrated (96%) formic acid
`and stirred at room temperature overnight. Formic acid was
`removed at room temperature under vacuum, leaving a brown
`solid. This material was dissolved in absolute ethanol (10-50
`mL) and 10% aqueous HCI (3-10 mL) and stirred at room
`temperature for 3 h. Solvent was removed by rotary evapora-
`tion to furnish the product as the hydrochloride salt. This
`material was suiliciently pure (‘or further transfomiation. The
`yield stated is the net for this three-step sequence.
`5-Amino-1-l(phenylmethy|)aminol-1H-benzimidazole
`8-carboxanride (9a): 90% yield; LRMS [MH‘] 267; ‘H NMR
`(CD300) r) 9.68 (s, 1H), 8.55 (s, 1H), 7.98 (s. 1H), 7.40-7.52
`(m, 5H), 5.81 (8, 2H).
`5-Amino-1-ll(4-tluoropheny|)Inethyl]arnino]-1H-benz-
`imidamle-6-carboxamide (91)): 93% yield; LRMS [MH‘I
`286; ‘H NMR (CD;0D) () 9.73 (s, 1H), 8.64 (s, 1H), 7.60-7.68
`(In, 21-1), 7.19 (apparent t, 2H, J = 8.5 Hz), 5.83 (s. 2H).
`5-[(4-Methyl-4-pipertuinyI)sulfonyll-2-propoxybenzo
`ic Acid. Lithium Salt. To a solution of methyl salicyclate
`(25.00 g. 0.16 mol) in 200 mL of DMF were added potassium
`carbonate (34.00 g, 0.25 mol) and Liodopropane (84.00 g. 0.49
`mol). The mixture was stirred at room temperature (‘or 24 h.
`The reaction was diluted with 400 mL of water and extracted
`with 5 x 100 mL of ether. The combined organic extracts were
`washed twice with brine. dried and concentrated to give a
`faintly yellow liquid that contained the product, methyl-2-
`propoxybenzoic acid and excess 1-iodopmpane. This mixture
`was added dropwisc at 0 °C to a mixture of 35 mL of
`chlorosulfonic acid and 10 mL of thionyl chloride over 30 min.
`
`Page 5 of 7
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`The dark red reaction was allowed to slowly warm to room
`temperature overnight. The mixture was cautiously poured
`over 1 kg of ice and stirred to deposit a yellow solid that was
`recrystallized from cyclohexane to furnish 13.00 g (0.045 mol,
`28% yield) of the corresponding sulfonyl chloride: mp 58- 59
`°C; “C NMR(CDC1.1)o 164.7, 163.9, 135.6, 132.7. 131.8, 121.5,
`113.6. 71.6. 52.9. 22.6. 10.7.
`1.3 g of this compound (6.23 mmol) was dissolved in 20 mL
`of methylene chloride and cooled to 0 °C in ice; 0.82 g (8.10
`mmol) of triethylamine was added. followed by 0.69 g (6.86
`mmol) of 4-methylpiperazine. The reaction was stirred in ice
`for 1.5 h, then diluted with 50 mL of methylene chloride and
`washed twice with water and dried. The organic phase was
`concentrated in vacuo leaving a clear colorless oil which
`partially solidified under vacuum to give 2.21 g (6.23 mmol,
`100% yield) of the desired sulfonamide:
`‘H NMR (CDCl;) 6
`8.15 (d. 1H. J = 2.5 Hz). 7.81 (dd. 1H. J = 2.5. 8.9 Hz). 7.05
`(d. 1H, J = 8.9 Hz). 4.07 (1. 2H. J = 6.4 Hz), 3.90 (8, 3H), 3.03
`(br apparent s, 4H), 2.47 (apparent t. 4H, J = 4.8 Hz), 2.26 (s,
`3H). 1.86-1.91 (m. 2H), 1.09 (t. 3H. J =