2444
`
`Med Chem 1991 34 24442452
`
`times the original volume of buffer and
`was resuspended in
`for 15 mm centrifuged again and resuspended
`incubated at 37
`in the original volume of buffer
`binding assay using
`bremazocine 0.5 aM was carried out as described above
`
`Acknowledgment We greatly appreciate receiving
`samples of benzomorphan standards
`its enantiomer
`S-3 and the enantiorner of
`S-3 from Dr
`R- and
`Herbert Merz Boehringer Ingelheim KG Germany We
`the support of this work by the National
`acknowledge
`Institute on Drug Abuse through research grants DA-03933
`and DA-06675
`
`Registry No
`134233-45-7
`134133-69-0
`134233-48-0
`134133-70-3 S.HC1 134233-67-3
`134233-47-9
`9.HC1 134308-16-0 th-10 52079-30-8 5R-11 58879-35-9
`5S-11 58879-36-0
`12 134133-71-4 13 134233-49-1 14
`134133-72-5 15 134233-50-4 16 isomer
`134133-73-6 16 isomer
`134233-51-5 18 isomer
`134133-74-7 18 isomer
`
`134233-46-8
`
`23134233 5592413423356-02513423357 130 134233-58-2
`31 134233-59-3 32 isomer
`134133-76-9 32 isomer
`134133
`134233 60-6 33 isomer
`134233
`33 isomer
`77
`61
`33 isomer 1-HC1 134233-62-8
`33 isomer 2.HC1 134308-15-9
`134233-63-9 34 isomer
`35 isomer
`34 isomer
`134233-64-0
`35 isomer
`134233-66-2
`134233-65-1
`
`Preparation and Anticonvulsant Activity of
`a-Heteroatoin-S ubstituted Amino Acids
`
`Series of Functionalized
`
`Harold Kohnt Kailash
`
`Sawhney Philippe LeGall David
`
`Robertsonh and
`
`David Leander
`
`of Chemistry Uniuer8ity of Houston Houston Texas 77204-5641 and Lilly Research Laboratories Eli Lilly
`Department
`Company Indianapolis Indiana 46285 Receiued December
`1990
`
`2a Select
`Potent anticonvulsant activity has been reported for RS-2-acetamido-N-benzyl-2-methylacetamide
`a-heteroatom substituted derivatives of 2a have been prepared 26 examples in which the a-methyl group has been
`replaced by nitrogen 3aq oxygen 3ru and sulfur 3vz containing moieties The functionalized amino acid
`seizure MES and horizontal
`screen tox tests in mice
`derivatives were evaluated in the maximal electroshock
`The most active compounds were RS-2-acetaniido-N-benzyl-2-methoxyaminoacetamide 31 and RS-2-
`3n After ip administration the MES ED values for
`acetamido-N-benzyl-2-methoxymethylaminoacetaniide
`316.2 mg/kg and 3n 6.7 mg/kg compared favorably with phenytoin 9.50 mg/kg
`
`amino acid derivatives 26 examples are presented In
`eluded in this survey are selected oxygen nitrogen and
`amino acids Analysis of the com
`sulfur-functionalized
`posite data set disclosed trends that further define the
`structureactivity relationships for this class of amino acid
`derived anticonvulsant agents
`Selection of Compounds
`RS Acetamido
`benzyl methylacetamide3 2a
`represented the parent compound in this study wherein
`the methyl group was replaced by select
`functionalized
`nitrogen oxygen and sulfur substituents Table
`In
`all cases the racemates were prepared and tested No
`attempts were made at this stage to resolve the enan
`tiomeric mixtures The a-nitrogen-substituted
`adducts
`consisted of the parent ammo 3a the monoalkylammo
`3bc the dialkylamino 3de and the trialkylammonium 3f
`derivatives as well as the corresponding monoaryl ana
`logues 3g and 3h Included in our a-nitrogen subset of
`compounds were three classes of functionalized amino
`These were the monoacyl derivatives 31 and
`derivatives
`the N-hydroxyamino adducts 3ko and the N-
`3j
`hydrazino compounds 3p and 3q The second set of
`structurally modified amino acid derivatives were the
`
`Nonnaturally occurring amino acids have become in-
`creasingly important in the design of pharmacologically
`active peptides and peptidomimetics.1
`Recently we re-
`ported the excellent anticonvulsant
`activity of certain
`functionalized amino acid derivatives 1.2
`Potent pro-
`seizures MES in
`tection against maximal electroshock
`mice was observed for functionalized amino acid racemates
`ai
`ontaining both an
`Ns
`stituent revealed that stringent steric and electronic re-
`quirements must be met for optimal activity The median
`effective dose ED for the a-methyl 2a 76.5 mg/kg
`and a-phenyl 2b 20.3 mg/kg derivatives4
`compared
`for phenobarbital7 21
`favorably with that observed
`mg/kg while those of the a-pyrrolyl 2c 16.1 mg/kg
`2d 10
`and
`adducts6 rivaled th
`/k
`-furan
`reported for phenytoin7 950mg/kg Furthermore
`parison of the two individual enantiomers of 2abd re-
`vealed that in each case the anticonvulsant activity resided
`stereoisomer 256
`primarily in the
`
`RlCNH.NHR3
`
`CH3CNH-f-NHCH
`
`25
`
`CH3
`
`Ph
`
`2-pyrrolyl
`
`A2
`
`2-f
`urany
`
`In the present study the synthesis and anticonvulsant
`novel series of a-heteroatom-substituted
`properties of
`
`Author to whom correspondence
`the University of Houston
`tUniversity of Houston
`Lilly Research Laboratories
`
`should be addressed to at
`
`Shunian
`Ornstein
`Org Chem 199055 738
`Am Chem Soc 1990 112
`
`Med Chem
`
`Kohn
`Conley
`
`Med Chern 1987 30 567
`Brain Res 1988 457
`Leander
`
`For leading references see
`Paschal
`Gesellchen
`Qiu
`Ojima Komata
`770 and references therein
`Kohn
`Chem Br 1988 24 231
`Conley
`Liao Z.-K Watson
`Kohn
`Cortes
`1985 28 601
`Conley
`Kohn
`371
`Kohn
`son
`Porter
`
`Sawhney
`Leander
`Cereghino
`Scoville
`
`Kupferberg
`1984 51 293
`
`LeGall
`Conley
`Robert-
`Med Chem 1990 33 919
`Hessie
`Gladding
`White
`Cleveland Clin
`
`0022-2623/91
`
`1834-2444$02.50/0
`
`1991 American Chemical Society
`
`MYLAN - EXHIBIT 1012
`
`

`
`Functionalized
`
`a-Heteroatom-Substituted Amino Acids
`
`Journal of Medicinal Chemistry 1991 Vol 34 No
`
`2445
`
`Table
`
`Selected Physical and Pharmacological
`
`Data in Mice for a-Heteroatom-Substituted Functionalized Amino Acid Derivatives
`
`3s
`
`II
`
`CH3CNH CH CNHCH2Ph
`
`II
`
`no
`
`3a
`
`3b
`
`3c
`
`3d
`
`31
`
`3g
`
`3h
`
`31
`
`3j
`3k
`
`31
`
`3m
`3n
`
`30
`
`NH2
`
`NHCH3
`
`NHCH2CH3
`
`NCH32
`
`NO
`
`NCH33 BF4
`NHPh
`
`NN
`
`NH
`
`NHCOCH3
`NHCOCF3
`NHOH
`NHOCH3
`
`NCH3OH
`NCH3OCH3
`
`P\
`
`mpb
`131133
`
`115117
`
`123125
`
`104106
`171172
`
`171173 dec
`183185
`
`135137
`
`265267 dec
`228-230
`144146 dec
`9597
`
`159161
`165167
`
`149151
`
`MESC
`EDs
`
`65.1
`56.275.3
`44.5
`37.052.4
`42.4
`37.247.8
`45.3
`
`30 100
`
`100
`300
`100
`
`100 300
`300
`-100
`6.2
`5.47.2
`30
`
`6.7
`5.77.7
`
`31.4
`26.737.8
`
`TD
`
`46.0
`38.056.0
`
`50.5
`40.459.9
`
`NHNHPh
`NHNHCO2CH2Ph
`
`OH
`
`OCH3
`
`OCH2CH3
`
`OPh
`SCH3
`SCH2CH3
`SPh
`SOCH2CH3
`SOCH2CH3
`SO2CH2CH3
`CH3
`
`Ph
`
`2-pyrrolyl
`
`2-furanyl
`
`132134
`152154
`
`136138
`
`145146
`
`153155
`
`125-128
`155157
`140142
`165167
`135137
`135137
`161163
`138139
`
`202203
`
`174175
`
`178179
`
`100 300
`
`112
`
`4539
`416.6501.0
`96.9
`79.8118.4
`30 100
`
`-40
`
`3p
`3q
`
`3r
`
`3sf
`
`3t1
`
`3u
`3v
`3w
`3x
`3y1
`3y-mix
`3z
`2a
`
`2b
`
`2c
`
`2d
`
`phenytoin
`
`phenobarbital
`
`valproate
`
`-100
`55.6
`49.363.9
`80.1
`70.691.0
`98.3
`84.4114.0
`62.0
`51.178.4
`100
`100
`30 100
`300
`100
`100
`100
`76.5
`66.689.0
`20.3
`16.924.5
`16.1
`13.219.9
`10.3
`9.111.6
`9.5
`8.110.4
`52.572.1
`69.0
`21.8
`15.022.5
`62.872.9
`426
`272
`247338
`369450
`The compounds were administered intraperitoneally ED and TD values are in milligrams per kilogram Number in parentheses are
`95% confidence intervals Time of peak effects in hours as determined in the Experimental Section is denoted in brackets 5Melting points
`MRS
`seizure test Compound was suspended in 30% PEG unless otherwise noted
`Tox
`maximal electroshock
`are uncorrected
`toxicity determined from horizontal screen unless otherwise noted e0 determined tReference
`Compound 3u was sus
`neurologic
`pended in acacia Reference
`Neurologic toxicity determined using the rotorod test Reference
`Reference
`Reference
`
`compounds 3ru This group was
`a-oxygen-substituted
`comprised of the a-hydroxy adduct 3r the two a-alkoxy
`derivatives 3s and 3t8 and the a-phenoxy compound 3u
`
`________________________________________________
`Kohn mt
`Sawhney
`LeGall
`Conley
`Peptide Protein Res 1988 32 279
`
`i.e
`similar battery of a-sulfur-substituted compounds
`3vx8 was selected for evaluation Attempts to synthesize
`the parent a-thiol derivative in the series were unsuc
`In addition to 3vx both the sulfoxide
`cessful however
`3y and the sulfone 3z derivatives of the ethylthio adduct
`3w were prepared
`
`

`
`2446
`
`Journal of Medicinal Chemistry 1991 Vol 34 No
`
`Kohn et al
`
`Scheme
`Preparation of a-Heteroatom-Substituted
`Functionalized Amino Acid Derivatives
`
`Method
`
`CH3CNH-CH2-COCH2CH3
`
`BrO
`
`CH3CNH-CH-COCH2CH2
`
`Br
`_______
`cci4
`
`/7
`
`excess xH
`
`THF -78
`
`cH3NH-cH-cNHCH2Ph
`
`CH3CNH-CH-COCH2CH3
`
`PhCH2NH2
`
`X0
`
`CH3OH
`
`21
`
`BBr3
`
`CH2CI2
`
`Br
`
`II
`
`II
`
`CH3CNH-CH-CNHCH2Ph
`
`excess XH
`
`THF-78
`
`or
`
`1Et3N
`2XH
`THF
`
`-78
`
`CH330
`BF
`
`BF
`NCH33
`
`CH3CNH-CH-CNHCH2Ph
`
`excess xti
`
`Met/rod
`
`_____
`MethodC
`
`Method
`
`QEt
`
`CH3CNH-CH-CNCH2Ph
`
`BFEt2O
`E120
`
`excess XH
`
`Chemistry
`Four different synthetic approaches Scheme methods
`AD were employed for the preparation of most of the
`
`a-heteroatom-substituted
`
`functionalized amino acid de-
`route method
`the a-bromo
`rivatives
`In the first
`was prepared in near quantitative yield using the
`ester
`from commercially
`protocol of Kober and Steglich9
`Treatment of with
`available0 ethyl acetamidoacetate
`an excess of the nucleophilic heteroatom species furnished
`the corresponding ethyl 2-substituted-2-acetamidoacetate
`6192% yields Formation of
`is presumed to proceed
`through the intermediacy of ethyl 2-acetyliminoacetate
`thick oil and used directly
`was isolated as
`In most cases
`step without extensive purification
`in the subsequent
`Treatment of with benzylamine and
`catalytic amount
`of NaCN gave the desired product
`in moderate yields
`2974% This method was used to synthesize compounds
`3ac 3e 3g and 3h Attempts to utilize this protocol
`prepare 3d 3k 3m and 3n were unsatisfactory
`In these
`cases the final benzylamine-mediated step did not proceed
`cleanly
`The difficulty encountered
`in converting several
`to the corresponding benzylamides
`functionalized esters
`led to the development of the second procedure method
`depicted in Scheme
`In this route the benzylamide
`moiety was incorporated within the framework of the am-
`mo acid derivative prior to the introduction
`of the
`heteroatom substituent Treatment of 3t with BBr3 in
`CH2CI2 led to the formation of the presumed a-bromo
`This adduct could not be fully purified or
`derivative
`
`to
`
`_________________________________________
`Liebigs Ann Chem 1983 599
`Kober
`Steglich
`10 Aldrich Chemical Co
`11 Hogberg
`Strom
`1987 52 2033
`
`Ebner
`
`Ramaby
`
`Org Chern
`
`to moisture and
`characterized due to the sensitivity of
`its poor solubility in nonhydroxylic solvents Accordingly
`either the addition of an excess of the heteroatom species
`or the sequential addition of triethylamine and the nu
`to THF mixture
`cleophilic heteroatom-containing
`reagent
`138%
`in moderate amounts
`furnished
`containing
`yields from 3t
`This method was employed for
`the
`preparation of compounds 3d 3k 3p and 3uw Included
`in the product mixture for 3k were the diastereomeric
`8a and 8b in which
`adducts
`reacted with
`equiv of
`NH2OH Implementation of this procedure for the syn
`thesis of 31o was not successful due to the difficulty
`en-
`countered in obtaining solutions of the free hydroxyamines
`in nonhydroxylic solvents Use of methanolic solutions of
`the hydroxyamines furnished only 3s
`
`II
`
`II
`
`CH3CNH
`
`..CNHCH2..Q
`
`NOH
`
`CH3CNH.CCNHCH2_Q
`iiHO
`
`II
`
`in
`
`Employment of the third protocol method
`outlined
`convenient procedure to circum
`in Scheme
`provided
`this obstacle Methylation of the dimethylamino
`vent
`adduct 3d with trimethyloxonium tetrafluoroborate in
`nitromethane furnished the quaternary ammonium de
`treatment of 3f with
`rivative 3f in high yields Subsequent
`methanolic solution containing the requisite hydroxy
`amine led to production of 31o in good yields 4282%
`Synthesis of the a-hydroxy 3r a-ethylthio 3w and
`a-thiophenoxy8 3x amino acid derivatives was accom
`pushed using the last technique depicted in Scheme
`which 3t was treated with BF3.Et20 in the presence of H20
`EtSH and PhSH respectively Scheme method
`similar protocol was utilized by us for the preparation of
`a-heteroaromatic functionalized amino acid derivatives.68
`This procedure proved superior than that of method
`for
`the preparation of 3w
`Two of the remaining compounds listed in Table
`3i
`and 3j were obtained by treatment of 3a with acetic an-
`hydride and trifluoroacetic anhydride respectively The
`final compounds 3y and 3z were prepared directly from
`the a-ethylthio adduct 3w Interestingly treatment of 3w
`with m-chloroperbenzoic acid in CH2C12 led to the ste
`reoselective production of the a-sulfoxide 3y-l 3C NMR
`reaction mixture indicated the
`the initial
`analysis of
`presence of only
`single diastereomeric enantiomeric pair
`The precise stereochemical
`compound
`identity of this
`adduct has not been established Correspondingly use of
`stoichiometric amounts of Na104 at room temperature in
`21 diastereo
`an aqueous methanolic solution yielded
`meric mixture 3C NMR analysis of 3y-1 and 3y-2 in
`which the major compound present corresponded to the
`product generated in the m-chloroperbenzoic acid reaction
`3y-l Attempts to completely separate these diastereo
`mers by either TLC or recrystallization proved unsuc
`23 mixture of 3y-l and 3y-2 ob
`cessful Accordingly
`tamed after fractional
`recrystallization was analyzed for
`anticonvulsant activity and is identified as 3y-mix We
`have tentatively attributed the diastereoselectivity of the
`m-chloroperbenzoic acid mediated process to the preor
`ganization of the oxidant with 3w in CH2CI2 Employment
`of excess Na104 with 3w at elevated temperatures 5060
`gave the ce-sulfone 3z in 32% yield
`Of note all 17 aa-diamino acid derivatives 3aq in-
`cluding the trimethylammonium adduct 3f were well
`
`

`
`Functionalized a-Heteroatom-Substituted Amino Acids
`
`Journal of Medicinal Chemistry 1991 Vol 34 No
`
`2447
`
`defined stable compounds.2 Only 3f 3i and 3k melted
`with decomposition
`
`Pharmacological Evaluation
`The a-heteroatom substituted amino acid derivatives
`were tested for anticonvulsant activity by using the
`procedures described by Krall et aL3 All compounds were
`administered intraperitoneally ip to mice Table
`lists
`
`Included in this
`
`the median effective dose ED values required to prevent
`seizures in the MES test by racemic
`table are the median neurotoxic dose TD values de-
`
`termined for select compounds using the horizontal screen
`test.4
`Evaluation of the results listed in Table
`several
`
`revealed
`
`important observations First the a-amino 3a
`a-alkylamino 3be and a-trimethylainmonium 3f de-
`rivatives all displayed anticonvulsant activities comparable
`to that observed for the a-methyl analogue 2a.34 Second
`the a-arylamino derivatives 3g and 3h were devoid of
`activity at doses below 100 mg/kg
`comparable reduc-
`tion in activity has been observed in proceeding
`from the
`a-methyl derivative 2a to the corresponding a-benzyl
`adduct4 and has been attributed in part to the stringent
`steric requirements that exist for maximal anticonvulsant
`activity in this class of compounds Third conversion of
`the a-amino derivative 3a to the corresponding a-acyl-
`amino adducts 3i and 3j led to
`decrease in activity of the
`test compound Fourth incorporation of an a-N-alkoxy-
`amino moiety i.e 31 3n 3o within the backbone of the
`compound led to
`pronounced improvement of the po-
`tency of the compound in the MES test compared to either
`2a or 3a
`corresponding enhancement
`in activity was
`not observed for the two N-hydroxyamino adducts 3k and
`3m The anticonvulsant activities of racemic 31 EDJ
`6.2 mg/kg and 3n EDse
`6.7 mg/kg were comparable
`to that of the RS-2-furanyl derivative 2d6 EDse
`10.3
`
`mg/kg and phenytoin7 ED 9.5 mg/kg Importantly
`in the most potent analogues 2d 31 and 3n
`func-
`tionalized oxygen atom existed two atoms removed from
`the a-carbon atom This pattern suggests that
`substi-
`tuted /3-heteroatom may be necessary for maximal activity
`Fifth the a-hydrazine derivatives 3p and 3q did not dis-
`play significant anticonvulsant activity Once again this
`property has been attributed in part to the steric size of
`these substituents Sixth the a-hydroxy 3r and the two
`a-alkoxy adducts 3s 3t displayed activity comparable
`to that reported for 2a The potency of the a-oxygen series
`was somewhat diminished from that observed
`the
`corresponding a-amino derivatives 3ac In agreement
`with previous findings4 the a-phenoxy adduct 3u displayed
`no activity at doses of 100 mg/kg or less Seventh within
`the a-sulfur series only the a-ethylthio adduct 3w ex-
`activity at doses less than 100
`hibited anticonvulsant
`mg/kg Eighth no enhancement
`of activity was noted for
`the three sulfur-oxygenated derivatives 3y-1 3y-mix and
`3z versus 3w This observation is consistent with the
`results obtained for the two N-hydroxyamino adducts 3k
`and 3m versus 3a
`
`for
`
`rivatives
`
`_______________________________________________
`12 For recent reports on the preparation of aa-diamino acid de-
`and related compounds
`see
`Katritzky
`Chem Soc Chem Commun 1989
`Mayence
`Urogdi
`Mayence
`Org
`337
`Katritzky
`Urogdi
`Chem 1990 55 2206
`Bock
`DiPardo
`Ibid 198651 3718
`Freidinger
`Fischer
`Ibid 1990 55 5225 and references therein
`13 Krall
`White
`Penry
`Kupferberg
`Swmyard
`Epilepsia 1978 19 409
`14 Coughenour
`McLean
`Parker
`Bjochem Behau 1977
`351
`
`Hassner
`
`Pharmacol
`
`Conclusions
`
`Straightforward procedures have been employed for the
`amino acid de
`preparation of a-heteroatom-substituted
`these compounds have
`that
`rivatives Despite the fact
`geminal heteroatoms
`to the carbonyl they are chemically
`well-defined and are exrected to serve as useful substrates
`The
`in future chemical and pharmacological studies
`pharmacological data obtained in this investigation pro-
`the structure
`vided additional
`information concerning
`activity profile of functionalized amino acid anticonvul
`santa The biological activities for
`reinforced our notions
`that stringent steric and electtonic requirements exist for
`maximal anticonvulsant activity in this class of compounds
`The potencies of 31 and 3n in the MES test were compa
`rable to those of phenytoin and 2d Additional studies in
`progress are aimed at investigating the generality of this
`class of compounds as well as their mode of action
`
`Experimental Section
`Chemistry General Methods Melting points were deter
`mined with
`Thomas-Hoover melting point apparatus and are
`Infrared spectra IR were run on Perkin-Elmer 1330
`uncorrected
`the 1601-cm
`and 283 spectrometers and were calibrated against
`band of polystyrene Absorption values are expressed in wave-
`numbers cm Proton
`NMR and carbon 3C NMR nuclear
`magnetic resonance spectra were taken on Nicolet NT-300 and
`General Electric QE-300 NMR instruments Chemical shifts
`are in parts per million ppm relative to Me4Si and coupling
`constants
`values are in hertz Low-resolution mass spectra
`MS were recorded at an ionizing voltage of 70 eV with
`Varian
`MAT CH-5 spectrometer at the Lilly Research Laboratories
`Microanalyses were provided by the Physical Chemistry De
`partment of the Lilly Research Laboratories Benzyl carbazate
`was obtained from Lancaster Synthesis Ltd Windham NH
`Thin-layer chromatography were run on precoated silica gel GHLF
`10 cm Analtech No 21521
`microscope slides 2.5
`Preparation of a-Heteroatom-Substituted Amino Acids
`Method
`Synthesis of Ethyl 2-Acetamido-2-substi-
`tuted-acetates General Procedure
`cooled -78
`solution
`mmol/10 mL was added slowly to
`equiv in THF
`of 59
`mmol/4 mL solution of the nitrogen nucleophile 510
`THF
`equiv at 78
`The reaction was stirred at this temperature
`The insoluble ma-
`and then at room temperature
`0.5
`terials were filtered and washed with THF The filtrate was
`concentrated in vacuo and the residue was purified by flash
`chromatography on Si02 gel using the indicated solvent as the
`to give the desired product
`eluent
`By use of this procedure the following compounds were pre
`pared
`Synthesis of Ethyl 2-Acetamido-2-aminoacetate 6a
`8.93 mmol and liquid NH3 56 equiv
`Compound
`2.00
`light brown residue which on purification by flash
`column chromatography on Si02 gel 5% MeOH/CHC13
`gave
`1.00 70% of 6a as
`0.21 5% MeOH/CHC13
`yellow oil
`NMR CDC13 61.31
`7.1 IIz
`
`yielded
`
`2.03
`
`2.61
`
`7.1 Hz
`7.1 Hz
`br
`4.24
`3C NMR CDC13 13.72 22.68 59.70
`7.1 Hz
`7.50
`61.73 170.40 170.68 ppm
`Synthesis of Ethyl 2-Acetamido-2-methylaminoacetate
`6b Use of 2.00
`8.93 mmol and MeNH2 2.50
`80.6 mmol
`The residue was purified by flash
`gave an oily residue 1.50
`column chromatography on 8102 gel 3% MeOH/CHC13 to yield
`65% of Gb as an oil R1 0.303% MeOH/CHCI3
`NMR
`1.00
`7.1 Hz
`CDC13
`2.36
`2.07
`1.32
`7.1 Hz
`7.4 Hz
`6.60 br
`4.26
`5.20
`the remaining amino proton was not detected 3C NMR
`170.40 ppm
`CDC13 14.02 23.06 30.84 62.04 65.72 170.09
`Synthesis of Ethyl 2-Acetanaido.2-ethylaminoacetate
`6c Employing
`9.38 mmol and EtNH2 1.40
`2.10
`31.04
`mmol gave
`brown residue The residue was purified by flash
`column chromatography on 8102 gel 3% MeOH/CHC13 to yield
`51% of Ge as
`light yellow oil R1 0.36 4% MeOH/
`0.90
`NMR CDC13
`CHC13
`6.7 Hz
`6.8 Hz
`6.7 Hz
`
`5.21
`
`1.87
`
`0.93
`
`2.48
`
`1.12
`
`4.05
`
`

`
`2448
`
`Journal of Medicinal Chemistry 1991 Vol 34 No
`
`Kohn et at
`
`7.1 Hz
`7.1 Hz
`6.8 Hz
`the remaining amino proton was not detected 3C NMR
`CDC1 13.64 14.55 22.53 39.06 61.3864.14 170.09 170.20 ppm
`Synthesis of Ethyl 2-Acetamido-2-dinsethylaminoacetate
`Sd Compound
`8.93 mmol and MeNH 56 equiv
`2.00
`NMR CDC13
`89% as
`gave 6d 1.50
`yellow oil
`7.1 Hz
`4.104.25
`2.23
`5.24
`
`5.05
`
`7.09
`
`1.25
`
`1.32
`
`2.07
`
`2.02
`NMR
`8.3 Hz
`8.3 Hz
`6.59
`CDC1 14.05 23.00 40.28
`61.84 69.24 169.38 170.57 ppm
`Synthesis of Ethyl 2-Acetamido-2-4-morpholinoacetate
`Se Use of morpholine 1.71
`19.64 mmol and
`2.00
`8.93
`mmol gave an oily residue which was purified by flash column
`chromatography on SiO gel 2% MeOH/CHC1 to give 1.90
`93% of Se as
`NMR
`thick oil R0.29 3% MeOH/CHC1
`CDC1
`6.8 Ffz
`2.432.72
`3.583.78
`7.9 Hz
`23.25 48.47
`
`6.39
`
`4.26
`7.9 Hz
`62.06 66.71
`
`5.27
`
`6.8 Hz
`NMR CDCI 14.21
`69.22 169.00 170.46 ppm
`Synthesis of Ethyl 2-Acetanildo-2-N-anilinoacetate 6g
`19.6 mmol and
`8.93 mmol
`2.00
`Use of aniline 1.83
`brown residue which was purified by flash column
`provided
`chromatography on SiO gel CHC12% MeOH/CHC1 gradient
`to yield 1.80 85% of 6g mp 8789
`recrystallized from
`ethyl acetate/petroleum ether R0.52 4% MeOH/CHC1 IR
`KBr 3340 1720 1635 1590 1490 730 710 cm NMR
`CDC1 61.29
`7.1 Hz
`4.27
`8.2 Hz
`8.2 Hz
`Hz
`6.43
`7.177.22 in
`the
`6.686.71
`6.806.83
`NMR CDC1
`remaining amino proton was not detected
`13.96 22.98 60.19 62.41 113.87
`119.29 129.37
`169.77 170.14 ppm mass spectrum FD 237 Md
`CH6NO
`Synthesis of Ethyl 2-Acetamido-2-3-pyrazolylamino-
`acetate 6h Use of
`8.93 mmol and 3-aminopyrazole
`2.00
`22.32 mmol and purification of the reaction product by
`on SiO gel 2% MeOH/CHC1 gave 1.80
`chromatography
`yellow oil R0.35 8% MeOH/CHC1
`89% of 6h as
`CDC1 61.21
`7.1 Hz
`1.89
`1.8 Hz
`Hz
`5.71 br
`5.73
`1.8 Hz
`7.1 Hz
`7.1 Hz
`7.29
`7.98
`NMR
`the remaining amino proton was not detected
`CDCI 13.73 22.49 61.41 62.02 91.79 130.53 153.02 169.96
`170.93 ppm
`Synthesis of Ethyl 2-Acetamido-2-hydroxyaminoacetate
`6k Use of
`9.38 mmol and anhydrous NHOH5 0.93
`2.10
`28.00 mmol gave an oily residue The residue was purified
`by flash column chromatography on SiO gel 5% MeOH/CHC1
`to give 1.00 61% of 6k The product was recrystallized from
`R1 0.24 5%
`EtOH to give white flaky solid mp 119121
`MeOH/CHC1 IR KBr 3300 1750 1660 1540 1390 610 cm
`I-I NMR DMSO-d8
`6.9 Hz
`5.09 dd
`6.9 Hz
`4.0 8.0 Hz
`6.06 br
`NMR
`8.0 Hz
`7.63
`8.50
`DMSO-d6 14.05 22.46 60.82 67.37 169.19 169.48 ppm mass
`spectrum FD 177 M4
`Anal C8HN204
`Synthesis of Ethyl 2-Acetamido-2-methylhydroxy-
`aminoacetate Sm MeNHOH 17.39 mmol prepared from
`MeNHOH.HC1 2.00
`23.95 mmol and NaOMe 0.94
`17.39
`4.46 mmol gave an oily residue The residue
`minol and
`1.00
`was triturated with EtOAc mL and the solid 0.70
`82%
`that remained was filtered and recrystallized from EtOH to give
`R1 0.34 5% MeOH/CHC1
`Sm as white solid mp 148150
`IR KBr 3320 3200 br 1760 1660 1530 1470 720 640 cm
`NMR DMSO-d6
`7.0 Hz
`1.89
`9.2 Hz
`4.004.20
`5.04
`NMR DMSO-d6 14.04
`9.2 Hz
`22.28 43.78 60.7971.48 168.29 170.23 ppm mass spectrum FD
`Anal C7H4N204.0.25HO
`192
`Synthesis of Ethyl 2-Acetamido-2-methoxymethyl-
`aminoacetate Sn MeNHOMe 17.40 mmol prepared from
`MeNHOMe.HCI
`22.32 mmol and NaOMe 0.94
`17.40
`mmol and
`4.46 mmol gave
`residue which was
`1.00
`on SiO gel 1%
`purified by flash column chromatography
`
`5.89
`
`5.64
`
`1.85
`
`4.10
`
`1.84
`
`7.1
`
`144.09
`Anal
`
`4.20
`
`7.1
`
`1.19
`
`1.87
`
`2.37
`
`8.43
`
`1.17
`
`8.17
`
`2.18
`
`15 Hurd
`
`Inorg Synth 1939
`
`87
`
`MeOH/CHC13 to give 0.60 66% of Sn as an oil R1 0.53 2%
`NMR CDC1 1.35
`MeOH/CHC1
`7.0 Hz
`7.0 Hz
`4.30
`2.62
`NMR CDC13
`8.9 Hz
`8.9 Hz
`14.06 22.89 40.30 60.01 61.89 70.16 168.14 170.53 ppm
`Synthesis of 2-Acetamido-N-benzyl-2-substituted-acet-
`amides
`General Procedure
`equiv
`mixture of
`benzylamine 1.2 equiv and NaCN 0.1 equiv in MeOH
`mmol/25 mL was stirred at 4550
`18
`The solvent was
`removed in vacuo and the residue was purified with either
`trituration with EtOAc or flash column chromatography on Si02
`gel using the indicated solvent as the eluent
`By use of this procedure the following compounds were pre
`pared
`Synthesis of 2-Acetamido-N-benzyl-2-aminoacetamide
`3a Compound Sa 1.00
`6.25 mmol benzylamine 0.80
`7.5
`mmol and NaCN 0.03
`0.61 mmol gave
`residue that solidified
`on standing 18
`The reaction mixture was triturated with
`EtOAc 20 mL The white solid 1.00
`72% that
`remained
`was filtered and then further purified by recrystallization from
`dec R1 0.21 5% MeOH/CHC1
`EtOAC mp 131133
`IR
`KBr 3300 1650 br 1530 br 1450 740 cm1
`NMR
`4.4 Hz
`DMSO-d6 61.83
`2.35 hr
`7.0 Hz
`8.31 hr
`7.207.32
`4.91
`13C NMR DMSO-d6 22.66 42.05 60.29
`8.51 hr
`139.23 169.24 170.67 ppm mass
`128.18
`126.67 127.10
`100 221
`spectrum m/e relative intensity 222
`Anal CHNO
`29 133
`Synthesis of 2-Acetamido-N-benzyl-2-methylainino-
`acetamide 3b Compound Sb 1.50
`8.63 mmol benzylamine
`10.35 mmol and NaCN 0.04
`0.82 mmol gave
`brown
`1.11
`residue that was purified by flash column chromatography on Si02
`gel 2% MeOH/CHC1 to yield 1.00 49% of 3b mp 115117
`recrystallized from ethyl acetate/petroleum ether R1 0.33
`MeOH/CHC1 IR KBr 3240 1610 br 1500 br 1430
`725670 cm NMR DMSO-d6 61.87
`2.18
`4.20-4.29 in
`7.9 Hz
`7.247.35
`7.9 Hz
`the remaining amino
`8.55 hr
`8.14
`NIvIR DMSO-d6 22.52 31.3742.04
`proton was not detected
`139.28 169.51 169.83
`65.99 126.68 127.12
`128.18
`
`3.48
`
`6.66
`
`2.12
`
`5.36
`
`4.28
`
`4.87
`
`1.81
`
`NMR
`127.50 128.64
`
`1.83
`
`3.56
`
`yield
`
`ppm AnaL CH7NO
`Synthesis of 2.Acetamido-N-benzyl-2-ethylaminoacet-
`ainide 3c Use of Sc 0.90
`4.79 mmol benzylamine 0.62
`5.75 mmol and NaCN 0.03
`0.51 mmol gave an oily residue
`that was purified by flash column chromatography on SiO gel
`to give 0.35 29% of 3c as white solid
`3% MeOH/CHCI
`in 123125
`recrystallized from ethyl acetate/hexane R1 0.34
`4% MeOH/CHC1 IR KBr 3250 1620 br 1510 br 1450
`br 740 680 cm NMR DMSO-d6
`6.8 Hz
`0.93
`2.402.48 in
`2.08 br
`4.22
`5.5 Hz
`7.8 Hz
`7.207.27 in
`4.90
`5.5 Hz
`7.8 Hz
`8.08
`8.48
`CDC1 15.14 22.97 37.65 43.53 65.68 127.44
`137.73 169.75 171.20 ppm Anal CH9NO
`Synthesis of 2-Acetamido-N-benzyl-2-4-morpholino-
`acetamide 3e Use of Se 0.59
`2.56 mmol benzylamine 0.28
`2.82 mmol and NaCN 0.01
`0.26 mmol gave
`thick oily
`residue The residue was triturated with EtOAc mL and the
`that remained was collected by filtration
`white solid 0.35
`to
`give 3e The filtrate was concentrated
`and the residue was
`on SiO gel 2%
`purified by flash column chromatography
`MeOH/CHC1
`trace amount
`The initial
`fractions furnished
`0.09
`of 2-acetamido-N-benzyl-2-benzylaminoacetamide
`of 3e
`Continued elution gave additional amounts 0.20
`2-Acetainido-N-benzyl-2-benzylaminoacetamide
`0.09 11% mp 135138
`R1 0.52 4% MeOH/CHC1 JR
`KBr 3250 br 1630 br 1500 br 1425 750 700 cm NMR
`13.6 Hz
`DMSO-d6
`3.52 hr
`5.4 Hz
`3.66
`4.23
`8.0 Hz
`8.0 Hz
`NMR DMSO-d6 22.63 42.11
`
`8.51
`
`13.6 Hz
`7.057.38
`5.4 Hz
`128.002
`48.5764.41 126.70 127.13
`128.30 139.29 140.12 169.61 169.90 ppm mass spectrum
`178 11
`12 311
`m/e relative intensity 312
`177 100 Anal C8HNO-0.25HO
`
`10
`
`8.20
`
`4.89
`
`128.13
`
`128.22
`
`

`
`Functionalized
`
`a-Heteroatom-Substjtuted Amino Acids
`
`3.51
`
`8.58
`
`4.28
`7.127.30
`
`13C
`
`3e
`2-Acetaniido.N-benzyl-2-4-morpholinoacetamide
`yield 0.55 71% mp 171172
`recrystallized from EtOAc
`lB KBr 3250 1620 1515 1440 740
`R1 0.35 4% MeOH/CHC13
`690 cm NMR DMSO.d6 51.87
`2.292.45
`4.23 dd
`4.1 Hz
`6.1 151 Hz
`dd
`9.1 Hz
`6.1 15.1 Hz
`5.08
`6.1 Hz
`9.1 Hz
`8.24
`DMSO-d6 22.39 42.20 48.43
`66.03 69.24
`126.76
`170.20 ppm mass
`127.13
`128.21
`168.02
`139.42
`spectrum m/e relative intensity 292
`233
`158
`19 157 100 116 26 115 100 106 29 9172 Anal
`C5H21N303
`Synthesis of 2-Acetamido-N-benzyl-2-N-anilinoacet-
`amide 3g fig 2.00
`8.47 mmol benzylamine 1.09
`10.00
`mmol and NaCN 0.04
`0.84 mmol gave
`white solid that
`separated during the course of the reaction The precipitate was
`filtered and purified by recrystallization from absolute EtOH to
`give 1.10 44% of 3g mp 183185
`IR KBr 3270 1630
`NMR DMSO-d6 51.84
`1520 1490 1430 740 690 cm1
`5.8 Hz
`8.1 Hz
`4.31
`8.1 Hz
`6.596.64
`6.706.72
`8.1 Hz
`7.207.33
`3C NMR DMSO-d6 22.46 42.25 60.42 113.21
`5.8 Hz
`117.22 126.72 127.16
`138.99
`128.18
`128.77
`145.88 168.65 169.70 ppm mass spectrum m/e relative intensity
`164 28 163 100 122 20 121 100 106
`297
`239
`47 104 65 93 63 91 77 Anal C17H19N302
`Synthesis of 2.Acetamido-N-benzyl-2-3-pyrazolyl-
`aminoacetamide 3h solution of 6h 1.60
`7.1 rnmol
`in
`MeOH 40 mL containing benzylamine 0.83
`7.8 mmol and
`NaCN 50 mg mmol was stirred at 4555
`TLC
`18
`analysis 8% MeOH/CHC13
`of the reaction mixture indicated
`the presence of only minor amount of product
`second lot
`of NaCN 50 mg mmol was then added and the reaction was
`allowed to proceed at 4555C
`and then at room temperature
`48
`The solvent was removed in vacuo and the residue was
`triturated with EtOAc 15 mL The insoluble solid that remained
`was filtered and purified by flash column chromatography on Si02
`gel 7% MeOH/CHCI3
`to give 0.90 44% of 3h mp 135137
`R1 0.35 8% MeOH/CHCI3 IR KBr 3230 br 1620 br
`1500 br 1430 730 690 cm NMR DMSO-d6 11.82
`5.9 Hz
`5.515.55
`7.187.40
`4.29
`3C NMR
`11.66 br
`8.53 br
`8.36 br
`DMSO-d6 22.59 42.29 61.79 90.68 126.67 127.07
`129.10 139.41 153.53 169.19 169.67 ppm mass spectrum
`230 28
`64 287
`m/e relative intensity 288
`229 100 153 46 Anal C4H7N50.0.5H20
`Preparation of Functionalized a-Heteroatom-Substituted
`Amino Acids
`Method
`General Procedure
`BBr3
`in CH2C12 1.1 equiv was added to
`solution
`solution of
`equiv in CHCl 10 mmol/125 mL The mixture was
`3t68
`stirred at room temperature
`and then concentrated to
`dryness in vacuo to give
`pale yellow crystalline material
`as
`was then dissolved in THF 10 mmol/250
`The bromo adduct
`mL cooled 78
`15-mm interval
`and then added over
`to
`cooled 78
`solution of the heteroatom nucleophile in THF
`mmol/ mL The reaction mixture was stirred at this tern-
`perature 30 mm and then at room temperature 90 mm The
`insoluble salts were filtered and the filtrate was concentrated
`in
`vacuo The residue was then purified by flash column chroma-
`tography on SiO gel using the indicated solvent as the eluent
`By using this procedure the following compounds were pre
`pared
`Synthesis of 2-Acetamido.N-benzyl-2-dlmethylainino-
`acetamide 3d By making use of 3t 3.00
`12.0 mmol BBr
`in CHC12 13.2 mL 13.2 mmol and Me2NH 56 equiv
`brown residue was obtained that was purified by flash column
`chromatography on Si02 gel 2.5% MeOH/CHCI
`to give 1.20
`40% of 3d The product was recrystallized from ethyl ace-
`tate/hexane to give light yellow cubic crystals mp 104106
`R1 0.39 5% MeOH/CHCI
`IR KBr 3280 1670 br 1500 br
`1460 760 700 cm NMR DMSO-d5
`2.11
`4.34 dd
`4.22 dd
`6.1 14.7 Hz
`5.2 14.7 Hz
`8.3 Hz
`7.237.31
`8.18
`5.11
`NMR DMSO-d6 22.43 40.33
`8.3 Hz
`8.55 br
`42.28 69.42 126.73 127.27
`139.49 168.49
`
`5.67
`
`8.41
`
`6.04
`7.067.11
`
`8.72
`
`128.17
`
`1.91
`
`128.21
`
`2449
`
`Anal C3-
`
`in
`
`4.31
`
`5.94 dd
`2.8 Hz
`3C NMR
`
`128.18
`
`Journal of Medicinal Chemistry 1991 Vol 34 No
`170.31 ppm mass spectrum FD 250 M4
`H9N302
`Synthesis of 2.Acetansido-N.benzyl-2-hydroxyamino-
`acetamide 3k Use of 3t 2.00
`8.0 mmol BBr3
`CHC12 8.8 mL 8.8 mmol and anhydrous NH2OH5 56 equiv
`gave an oily residue The residue was separated
`into three corn
`on Si02 gel 7.5% MeOH/
`ponents by flash chromatography
`CHCI
`2-Acetamido-N-benzyl-2-hydroxyaminoacetamide 3k
`yield 0.14 7% mp 144146
`dec recrystallized from EtOH
`IR KBr 3320 br 1660 br 1540
`R10.30 8% MeOH/CHC13
`br 1460 750 700 cm NMR DMSO-d6 1.88
`5.08 dd
`4.4 8.1 Hz
`5.7 Hz
`2.8 4.4 Hz
`7.197.35
`7.52
`5.7 Hz
`8.1 Hz
`8.42
`8.26
`DMSO-d6 22.69 42.25 67.86 126.69 127.14
`139.08 168.53 169.67 ppm mass spectrum FD 238
`Anal C1H5N303
`Compound 8a yield 0.05 3% mp 177179
`recrys
`IR KBr 3240
`tallized from EtOH R1 0.27 8% MeOH/CHC13
`br 1640 br 1510 br 1450 690 cm NMR DMSO-d6
`9.3 Hz
`9.3 Hz
`5.8 Hz
`3C NMR DMSO.d6 22.54
`42.30
`ppm mass spectrum FD 442
`168.24
`169.33
`Anal C22H27N505
`Compound 8b yield 0.10 6% mp 184186
`recrys
`talllzed from MeOH R1 0.18 8% MeOH/CHC13
`IR KBr 3300
`br 1660 br 1530 br 1450 740 700 cm NMR DMSO-d6
`4.44 dd
`4.20 dd
`5.3 15.3 Hz
`1.87
`9.0 Hz
`15.3 Hz
`7.157.31
`10
`8.39 dd
`5.3 6.2 Hz
`9.0 Hz
`3C NMR DMSO-d6 22.50
`42.58
`ppm mass spectrum FD 442
`
`1.82
`7.207.33
`
`8.51
`
`4.254.34
`
`10
`
`8.16
`
`5.21
`
`8.26
`
`67.55
`
`126.63
`
`127.13
`
`128.11
`
`139.02
`
`5.28
`
`127.23
`
`128.22
`
`139.08
`
`6.2
`
`8.00
`
`8.51
`
`69.98
`
`126.73
`
`167.60
`169.57
`Anal CnHvN5O5
`
`3.00
`
`as
`
`4.89
`
`7.4 Hz
`
`7.4 Hz
`8.60
`22.88 42.2266.22 112.66
`139.12
`128.53
`
`Improved Synthesis of 2-Acetamido-N-benzyl-2-hy-
`droxyaminoacetamide 3k Compound
`prepared from 3t
`in CH2C12 17.2 mL 17.2 mmol
`12.0 mmol and BBr3
`was dissolved in THF 250 mL cooled 10
`and then added
`dropwise 30 mm to
`suspension of NHOH 56 equiv in THF
`The reaction mixture was stir