J. Med. Chem. 1994,37, 4567-4571
`
`4567
`
`Synthesis and Anticonvulsant Activities of a-Acetamido-N-benzylacetamide
`Derivatives Containing an Electron-Deficient a-Heteroaromatic Substituent
`
`Patrick Bardel, Antoinette Bolanos, and Harold Kohn*
`Department of Chemistry, University of Houston, Houston, Texas 77204-5641
`Received August 17, 1994@
`Recent studies have demonstrated that C(a)-substituted a-acetamido-N-benzylacetamides
`displayed excellent anticonvulsant activities in mice. Analysis of the structure-activity
`relationship for this series of compounds has shown that placement of small, electron-rich
`aromatic and heteroaromatic groups at the C(a) site led to pronounced protection against MES-
`induced seizures. In this note, synthetic protocols are reported for the preparation of three
`novel nonnaturally occurring electron-deficient C(a)-aza aromatic a-acetamido-N-benzylaceta-
`mides (i.e., pyrid-2-yl (ll), pyrazin-2-yl (12), pyrimid-2-yl (13)). Expedient syntheses for 12
`and 13 were developed using a phase-transfer, nucleophilic aromatic substitution process. All
`three adducts exhibited potencies comparable to or greater than phenytoin in the MES test
`(mice, ip). These findings required us to modify in part the previously proposed structure-
`activity relationship for this class of anticonvulsants.
`
`Recently, we have reported on the potent anticonvul-
`sant activities of selectively C(a)-substituted function-
`alized amino acid derivatives l.lP7 Evaluation of the
`optimal R2-substituent in 1 (Table 1) revealed that the
`placement of a small, electron-rich heteroaromatic
`ring517 at the C(a) position, as well as the incorporation
`of a heteroatom two atoms removed from this carbon
`led to compounds (i.e., 2, 3) providing excellent
`protection against MES-induced seizures in mice. In
`this note, we describe the pharmacological activities of
`the three six-membered electron-deficient aza aromatic
`analogues, 11-13. Synthetic strategies are provided for
`these novel nonnaturally occurring amino acid deriva-
`tives. Significantly, the pronounced activities observed
`for 11-13 required us to modify in part the previously
`proposed structure-activity relationship for this class
`of anticonvulsants.
`
`0 $ 0
`I
`I
`I1
`R' c NH- cu c NHF?
`I
`H
`1
`
`0 $ 0
`I
`II
`I1
`CH,C N H - C r C NHCHZPh
`I
`H
`
`Chemistry
`Preparation of the pyrid-2-yl derivative 11 was ac-
`complished in 15% yield by treatment of a-acetamido-
`a-bromo-N-benzylacetamide6 (14) with 2-pyridyllithium8
`(2.1 equiv). Attempts to increase the yield for this
`transformation by varying the mole ratios of the reac-
`tants, inversing the order of addition of the reactants,
`
`and substituting lithium (2-pyridyl)cyanocuprateg for
`2-pyridyllithium were unsuccessful.
`The low yields observed for the synthesis of 11
`suggested that an alternative protocol be used for the
`preparation of the C(a)-pyrazin-2-y1 (12) and C(a)-
`pyrimid-2-yl (13) adducts. ODonnell and co-workers
`have described a general synthesis of C(a)-alkyl-
`substituted amino acids from glycine derivatives using
`a phase-transfer, nucleophilic aliphatic substitution
`reaction.l0 The corresponding nucleophilic aromatic
`substitution process has not been reported. Adopting
`this methodology, commercially available ethyl N-(diphe-
`nylmethy1ene)glycinate (15) was treated with solid
`potassium carbonate, tetra-n-butylammonium bromide,
`and either 2-chloropyrazine or 2-chloropyrimidine in
`1-methyl-2-pyrrolidinone to afford the C(a)-pyrazin-2-
`yl (16) and C(a)-pyrimid-2-yl (19) derivatives, respec-
`tively (Scheme 1). Subsequent hydrolysis of 16 and 19
`with aqueous 1 N HC1 furnished 17 and 20, respectively,
`in quantitative yield. Compounds 17 and 20 were
`acetylated with acetic anhydride and triethylamine in
`CHzClz at room temperature to give 18 and 21, respec-
`tively, and then converted to the desired compounds 12
`and 13, respectively, with benzylamine in EtOH using
`NaCN as a catalyst.ll The four-step conversion of ethyl
`N4diphenylmethylene)glycinate (15) to C(a)-pyrazin-2-
`yl(12) and C(a)-pyrimid-2-~1(13) proceeded in 33% and
`12% overall yield, respectively. We are unaware of
`other reports describing the syntheses of these novel
`C(a)-diazinyl amino acid derivatives. Efforts to improve
`the overall synthetic yield for 12 by first converting 16
`to the benzylamide 22 and then deprotecting the amine
`to give 23, followed by acetylation, furnished 12 in 12%
`overall yield. Attempts to use this phase-transfer
`method to prepare the pyrid-2-yl derivative 11 were
`unsuccessful. Treatment of 15 with 2-bromopyridine at
`150 "C (3 d) led to the recovery of the starting glycinate.
`
`t P N
`N /
`
`0 II
`H 2 N ~ - N H - C H 2 ~
`
`22
`0 1994 American Chemical Society
`
`23
`
`@
`
`~
`
`~
`
`Abstract published in Advance ACS Abstracts, November 15,1994.
`0022-2623/94/1837-4567$04.50/0
`
`~
`
`~~
`
`~~
`
`~
`
`IPR2014-01126- Exhibit 1034 p. 1
`
`

`
`4668 Journal of Medicinal Chemistry, 1994, Vol. 37, No. 26
`Scheme 1. Synthesis of Compounds 12 and 13
`
`=N
`
`5?
`I
`
`HCI. HzN
`
`C- OEt
`It
`0 u
`
`1. EIaN, CH&Iz
`2. AQO
`
`aq. 1 N HCI
`
`1
`
`EWJ
`
`fi
`N /N
`
`HCI. H2N'C-
`
`I1 OEt
`0
`2Q
`
`1
`
`I. EIjN, CH&k
`2. ACzO
`
`u
`
`21
`
`Pharmacological Evaluation
`The racemic aza aromatic amino acid derivatives 11-
`13 were tested for anticonvulsant activity using the
`procedures described by Krall and co-workers,12 and
`these results were compared to the findings previously
`reported for 2-10.5,7 All compounds were administered
`intraperitoneally (ip) to mice. Table 1 lists the ED50
`values required to prevent tonic extension of the hind
`limbs in mice in the MES test by 2-13. Included in
`this table are the median neurologically impairing dose
`(TD50) values using either the rotorod13 or horizontal
`screen14 test. In those cases when no activity was
`observed below 100 mgkg in the MES test, the TDSO'S
`were not determined. The protective index (PI = TD5d
`ED50) for 2-13, where appropriate, is also provided in
`Table 1.
`The ED50 values in the MES test for 11-13 (ED50 =
`8.1-14.8 mgkg) were comparable to those for pheny-
`toin15 (ED50 = 9.5 mgkg).16 Significantly, the MES
`ED50 values for 11-13 were also similar to those
`observed for 2 and 3, indicating that placement of an
`electron-deficient aromatic ring at the C(a) site did not
`lead to a reduction of activity. Previously, we have
`suggested that improved activity would result with the
`incorporation of an electron-rich aromatic group at the
`C(a) site (i.e., 2 (ED50 = 10.3 mgkg), 3 (ED50 = 16.1
`mgkg), 4 (ED50 = 44.8 mg/kg)).5,7 We have also
`presented evidence that placement of a substituted
`heteroatom two atoms removed from the C(a) site
`provided enhanced protection against MES-induced
`
`Notes
`seizures (i.e., 4 (ED50 = 44.8 mgkg) vs 5 (ED50 = 87.8
`mg/kg)).5-7 In agreement with this latter trend, 13 was
`more potent than either 11 or 12. Our findings that
`11-13 all displayed excellent activity in the MES test
`indicated that of these two structural determinants the
`latter was the more important factor for anticonvulsant
`activity. Consistent with this theory was the notable
`protection observed for the C(a)-heteroatom adducts 24
`(ED50 = 6.2 mgkg) and 25 (ED50 = 31.4 mgkg) in the
`MES testa6
`The pronounced activities of 12 and 13 contrasted
`with the results reported for 7 and 8.7 These two C(a)-
`imidazole adducts exhibited no protection in the MES
`test at 100 mgkg, while the corresponding oxazol-2-yl
`(6) (ED50 = 10.4 mg/kg) and thiazol-2-y1(9) (ED50 = 12.1
`mg/kg) derivatives provided significant protection against
`MES-induced seizure^.^ We have attributed the differ-
`ence in activities of 6-9 to the basicities of diazoles 7
`and
`The activities observed for the two weakly basic
`diazines 12 and 1317 were consistent with this notion.
`Conclusions
`Three C(a) electron-deficient a-acetamido-N-benzyl-
`acetamides (11-13) have been prepared and evaluated.
`Expedient syntheses are reported for the novel C(a)-
`pyrazin-2-yl and C(a)-pyrimid-2-yl derivatives. All
`three C(a)-aza aromatic functionalized amino acid
`derivatives displayed activity comparable to phenytoin
`in mice.
`Experimental Section
`Chemistry. General Methods. Melting points were
`determined with a Thomas-Hoover melting point apparatus
`and are uncorrected. Infrared spectra (IR) were run on Perkin-
`Elmer 1330 and 283 spectrometers and calibrated against the
`1601 cm-I band of polystyrene. Absorption values are
`expressed in wavenumbers (cm-I). Proton ('H NMR) and
`carbon (I3C NMR) nuclear magnetic resonance spectra were
`taken on Nicolet NT-300 and General Electric QE-300 NMR
`instruments. Chemical shifts (6) are in parts per million (ppm)
`relative to Me4Si, and coupling constants (J values) are in
`hertz. All mass spectra were taken by Dr. M. Moini at the
`University of Texas at Austin on a Finnegan MAT TSQ-70
`instrument. The N-(diphenylmethy1ene)glycinate (15) and
`BBr3 were purchased from Aldrich Chemical Co. (Milwaukee,
`WI). Thin-layer chromatography was performed on precoated
`silica gel GHLF microscope slides (2.5 x 10 cm; Analtech No.
`21521).
`Synthesis of a-Acetamido-a-bromo-N-benzylaceta-
`mide (14). To a stirred solution of a-acetamido-a-ethoxy-N-
`benzylacetamide's (2.00 g, 8 mmol) in dry CHzC12 (200 mL)
`was introduced a solution of BBr3 (16 mL, 16 mmol, 1.0 M in
`CHzC12) by means of a syringe under a N2 atmosphere. The
`Nz line was removed, and the reaction mixture was sealed.
`The yellow solution was stirred at room temperature (20 h)
`and then concentrated in vacuo to give a yellow solid. The
`solid was successively triturated with distilled Et20 (3 x 50
`mL) and ethanol-free CHC13 (neutral Al) (2 x 50 mL) and dried
`under high vacuum (0.1 Torr, 48 h) to give 1.94 g (85%) of 14:
`mp 162-163 "C; 'H NMR (acetone-de) 6 2.04 (s, C(O)CHd, 4.38
`(d, J = 15.0 Hz, CHH), 4.49 (d, J =15.0 Hz, CHH'), 6.66 (s,
`CHI, 7.23-7.39 (m, 5 PhH), the two NH protons are believed
`to be beneath the aromatic signals; 13C NMFl (acetone&) 23.03
`(C(O)CH3), 43.57 (CHz), 55.90 (CH), 127.99 (Cd'), 128.29 (2C2'
`or ~CS'), 129.24 (2Ca' or ~CS'), 139.33 (CI'), 166.05 (C(O)CH3),
`169.93 (C(0)NH) ppm; MS, CI(-) (re1 intensity) 204 (1001, 163
`(100); M, (+CI) 285.02368 [M + 11+ (calcd for CIIHMBTNZOZ
`285.02386).
`Synthesis of a-Acetamido-N-benzyl-a-(pyrid-2-yl)ac-
`etamide (11). A cooled (-100 "C) THF solution of 2-pyridyl-
`lithiums (60 mL, 8.0 mmol) was added dropwise to a cooled
`
`IPR2014-01126- Exhibit 1034 p. 2
`
`

`
`Notes
`
`Journal of Medicinal Chemistry, 1994, Vol. 37, No. 26 4669
`
`Table 1. Physical and Pharmacological Data in Mice for C(a)-Heteroaromatic a-Acetamido-N-benzylacetamidesa
`
`no.
`2fg
`
`R2
`
`Q-
`
`6h,i
`
`11'
`
`12'
`
`13'
`
`mPb
`178-179
`
`174-175
`
`167-169
`
`198-199
`
`164-166
`
`228-230
`
`188-191 (d)
`
`166-167
`
`202-203
`
`145-147
`
`185-187
`
`174-176
`
`MES' ED50
`10.3
`(9.1-11.6)
`16.1
`(13.2- 19.9)
`44.8
`(38.9-51.4)
`
`87.8
`(69.9-150)
`
`10.4
`(9.2-11.6)
`
`> 100
`
`> 100
`
`12.1
`(9.5-14.5)
`
`32.1
`(27.5-40.2)
`
`10.8
`(9.1-12.1)
`
`14.8
`(12.5- 17.2)
`
`8.1
`(5.5-11.5)
`
`to& TD50
`-40
`
`230, <lo0
`
`>30, <lo0
`
`> 100
`
`38.W
`(33.8-46.0)
`k
`
`k
`
`69. lj
`(61.6-78.6)
`
`>40
`
`225, <lo&
`
`58.2i
`(46.3-72.5)
`
`56.7j
`(48.5-64.9)
`
`Pie
`r3.9
`
`-
`
`-
`
`3.7
`
`-
`
`-
`
`5.7
`
`-
`
`3.9
`
`7.0
`
`6.9
`
`3.2
`
`1.6
`
`CY-
`
`-N
`phenytoinm
`
`phenobarbitalm
`
`valproatem
`
`9.5
`65.5
`(52.5-72.1)
`(8.1-10.4)
`21.8
`69.&
`(15.0-22.5)
`(62.8-72.9)
`42&
`272
`:247-338)
`(369-450)
`I
`(I The compounds were administered intraperitoneally. ED50 and TD50 values are in mgkg. Numbers in parentheses are 95% confidence
`intervals. A dose-response curve was generated for all compounds that displayed sufficient activity. The dose-effect data for these
`compounds were obtained at 0.5 h (''time of peak effect") except for compounds 9, 11, and 13, which were obtained at 0.25 h. Melting
`points ("C) are uncorrected. MES = maximal electroshock seizure test. tox TD50 = neurologic toxicity determined from horizontal
`(Indianapolis, IN). Reference 7. ' The compounds were tested through the auspices of the National Institute of Neurological and
`screen unless otherwise noted. e PI = protective index (TD5dED50). f Reference 5 . 8 The compounds were tested at the Eli Lilly Co.
`Communicative Disorders and Stroke at the National Institutes of Health. j TD50 value determined from the rotorod test. Not determined.
`Reference 2. Reference 15.
`
`or ~CS'), 129.37 (2C2' or ~CS'), 138.62 ((21' or c4), 139.53 (CI'
`(-100 "C) THF solution (100 mL) of compound 14 (0.90 g, 3.9
`or C4), 150.11 (Ce), 157.10 (Cg), 171.29 (C(O)CHs), 172.10
`mmol). The reaction mixture was stirred at -100 "C (2 h),
`(C(O)NH) ppm. Anal. (C1eH17N302) C, H, N.
`and then the reaction was quenched with a saturated aqueous
`Synthesis of Ethyl a-(Pyrazin-2-yl)-N-(diphenylmeth-
`solution of NH&l (40 mL) at -78 "C. The mixture was
`y1ene)glycinate (16). A heterogeneous mixture containing
`warmed to 0 "C, during which time a saturated aqueous
`15 (10.00 g, 37.5 mmol), 2-chloropyrazine (8.58 g, 74.9 mmol),
`solution of NazC03 was added dropwise until the precipitate
`tetra-n-butylammonium bromide (12.07 g, 37.5 mmol), KzCO3
`dissolved. The aqueous layer was extracted with CHzClz (3 x
`(9.00 g, 112.4 mmol), and 1-methyl-2-pyrrolidinone (70 mL)
`100 mL). The organic layers were combined, dried (NazSO*),
`was heated at 100 "C (3 d). The mixture was diluted with
`concentrated under vacuum, and then further purified by flash
`acetone (100 mL) and filtered through Celite. The solvents
`column chromatography on Si02 using 5% MeOWCHCL as
`the eluant to afford 340 mg (15%) of 11. The product was
`were removed in vacuo, and the residue was purified by flash
`recrystallized from chloroformhexanes: mp 146- 147 "C; Rf
`column chromatography on Si02 using 33% ethyl acetatel
`hexanes as the eluant to give 10.00 g (77%) of 16 as an oil: Rf
`0.40 (5% CH30WCHCl3); 'H NMR (DMSO-de) 6 1.94 (s, C(0)-
`C&),4.27(d, J=6.0H~,CH2),5.58(d,J=8.1H~,CH),7.17-
`0.38 (33% ethyl acetatehexanes); IR (neat) 3061,2984, 1738,
`7.34 (m, 5 PhH and CsH), 7.45 (d, J = 7.2 Hz, C3H), 7.76-
`1659, 1448, 1398, 1277, 1022, 702 cm-l; lH NMR (CDCl3) 6
`7.82 (m, C a ) , 8.51-8.54 (m, CeH and NH), 8.76 (t, J = 6.0
`1.17 (t, J = 7.2 Hz, OCH&&), 4.14 (q, J = 7.2 Hz, OCH2-
`Hz, NH); 13C NMR (DMSO-de) 22.57 (C(O)CH3), 44.57 (CHZ),
`CH3), 5.43 (s, CH), 7.14-7.44 (m, 10 PhH), 8.45 (s, C5H or
`60.22 (CH), 122.65 (Cs), 123.54 (Cs), 127.51 (C4'),128.20 (2C2'
`CsH), 8.46 (s, C5H or CeH), 8.97 (s, C3H); 13C NMR (CDC13)
`
`IPR2014-01126- Exhibit 1034 p. 3
`
`

`
`4570 Journal of Medicinal Chemistry, 1994, Vol. 37, No. 26
`
`13.81 (OCHZCH~), 61.39 (OCHzCHs), 70.06 (CHI, 127.44,
`127.87,128.12, 128.48, 128.86, 130.62,135.46,138.78 (2c&,),
`143.40 (C5 and Ce), 144.88 (C3), 154.18 (C2), 169.32 (C(O)OCHz-
`CH3 or C(N)), 172.14 (C(O)OCHzCH3 or C(N)) ppm; MS, CI-
`(+) (re1 intensity) 346 (M+ + 1, 1001, 272 (75); M, (+CI)
`346.15563 [M+ + 11 (calcd for CZIHZON~OZ
`346.15555). Anal.
`
`(CZ~H~~N~OZ.O.~HZO) C, H, N.
`Synthesis of Ethyl a-(Pyrimid-2-yl)-N-(diphenylmeth-
`y1ene)glycinate (19). Using the preceding procedure (100
`"C, 2 d) and 15 (10.00 g, 37.5 mmol), 2-chloropyrimidine (3.53
`g, 74.9 mmol), tetra-n-butylammonium bromide (12.07 g, 37.5
`mmol), KzCO3 (9.00 g, 112.4 mmol), and 1-methyl-2-pyrroli-
`dinone (70 mL) gave 3.30 g (26%) of 19 as an oil: Rf0.40 (50%
`ethyl acetatehexanes); IR (KBr) 3053,2991,1735, 1652,1449,
`1397, 1279, 1025, 640 cm-l; IH NMR (DMSO-de) 6 1.09 (t, J
`= 7.2 Hz, OCHzCHs), 4.10 (d, J = 7.2 Hz, OCH2CH31, 5.28 (s,
`CH), 7.18-7.57 (m, 10 PhH and CsH), 8.81 (d, J = 5.4 Hz,
`CJI and CsH); 13C NMR (DMSO-ds) 13.72 (OCHZCH~), 61.04
`(OCHZCH~), 119.49 (C5), 127.51, 127.59, 128.24, 128.55,
`128.87, 130.25, 135.67, 138.94 (2 C6H5), 157.14 (c4 and Ce),
`CH3 or C(N)) ppm; MS, CI(+) (re1 intensity) 346 (M+ + 1,100),
`166.83 (CZ), 169.22 (C(O)OCHZC& or C(N)), 172.00 (C(0)OCHz-
`272 (62); M , (+CI) 346.15580 [M+ + 11 (calcd for C21HzoN302
`
`346.15555). Anal. (CZ~H~~N~OZ*O.~HZO) C, H, N.
`Synthesis of Ethyl a-(Pyrazin-2-yl)glycinate Hydro-
`chloride (17). Compound 16 (6.00 g, 17.4 mmol) was dis-
`solved in Et20 (100 mL), and an aqueous 1 N HC1 solution
`(21 mL, 21.0 mmol) was slowly added, and the mixture was
`stirred at room temperature (20 h). The layers were separated,
`and the aqueous layer was washed with Et20 (3 x 30 mL).
`The aqueous layer was kept, and the solvent was removed in
`vucuo. The residue was triturated with acetone to give 3.20 g
`(95%) of 17: mp 165-167 "C (dec); IR (KBr) 2990,2908,2654,
`1748,1524,1421,1252,1157,1020,856 cm-l; IH NMR (CD3-
`OD) 6 1.10 (t, J = 7.2 Hz, OCHzCHs), 4.17 (9, J = 7.2 Hz,
`OCHZCH~), 5.56 (s, CHI, 8.69 (s, C5H or CeH), 8.71 (s, C5H or
`C a ) , 8.86 (s, CJ3); 13C NMR (CD30D) 14.23 (OCHZCH~), 54.66
`(CHI, 63.50 (OCHZCH~), 145.01 (CS or C5 or CS), 145.51 (C3 or
`C5 or CS), 146.21 (CS or C5 or CS), 147.80 (CZ), 166.92
`(C(O)OCHzCH3) ppm; MS, CI(+) (re1 intensity) 182 (M+ + 1,
`100); M, (+CI) 182.09279 [M+ + 11 (calcd for C8H12N302
`182.09295). Anal. (C~HIIN~OZ) C, H, N.
`Synthesis of Ethyl a-(Pyrimid-2-yl)glycinate Hydro-
`chloride (20). Using the preceding protocol (room tempera-
`ture, 3 h) and 19 (3.30 g, 9.6 "011,
`Et20 (50 mL), and aqueous
`1 N HCl(10 mL, 10.0 mmol) gave 1.80 g (87%) of 20: mp 156-
`158 "C (dec); IR (KBr) 2978, 2864, 2623, 1744, 1570, 1499,
`1422, 1373,1260,1211,1055,854 cm-'; IH NMR (CD30D) 6
`1.25 (t, J = 7.2 Hz, OCHzCHs), 4.29 (9, J = 7.2 Hz, OCHa-
`CH3), 5.44 (9, CH), 7.61 (t, J = 4.8 Hz, C5H), 8.94 (d, J = 4.8
`Hz, CJI and C a ) ; 13C NMR (CD30D) 14.26 (OCHZCH~), 59.44
`(CH), 64.27 (OCHZCH~), 123.01 (CS), 159.46 (C4 and Ce), 162.
`182 (M+ + 1, 100); M, (+CI) 182.09275 [M+ + 11 (calcd for
`03 (Cz), 167.18 (C(O)OCHzCH3) ppm; MS, CI(+) (re1 intensity)
`C8H12N302 182.09295). Anal. (CsHllN302) C, H, N.
`Synthesis of Ethyl a-Acetamido-a-(pyrazin-2-yl)ac-
`etate (18). Compound 17 (3.20 g, 14.7 mmol) was dissolved
`in CHzClz (50 mL), and then Et3N (2.05 mL, 14.7 mmol) was
`slowly added and the reaction mixture was stirred at room
`temperature (30 min). Ac20 (1.95 g, 19.1 mmol) was added
`slowly, and the reaction mixture was stirred (20 h). The
`solution was washed with HzO (30 mL) and dried (NazS04),
`and the solvent was removed to afford 3.10 g (94%) of 18 as
`an oil: Rf0.24 (EtOAc); IR (neat) 3053,2987,1734,1670, 1525,
`1408, 1375, 1157, 988 cm-l; 'H NMR (CDC13) 6 1.21 (t, J =
`7.2 Hz, OCH~CHS), 2.10 (s, C(O)CHs), 4.20 (9, J = 7.2 Hz,
`OCH~CHB), 5.94 (d, J = 7.8 Hz, CHI, 7.92 (d, J = 7.8 Hz, NH),
`8.54 (s, CsH or CeH), 8.58 (s, CsH or CeH), 8.84 (9, C3H); l3C
`NMR (CDC13) 13.28 (OCHZCH~), 21.95 (C(O)CH3), 54.89 (CH),
`61.42 (OCHZCH~), 143.31 (CS or C5 or CS), 143.61 (CS or C5 or
`CS), 144.23 (CS or Cs or CS), 150.73 ((221, 168.39 (C(0)OCHz-
`CH3 or C(O)CH3), 169.61 (C(O)OCHzCH3 or C(0)CHs) ppm;
`MS, CI(+) (re1 intensity) 224 (M+ + 1, 100); M, (+CI)
`224.10307 [M+ + 11 (calcd for C10H14N303 224.10352). Anal.
`(CioHi3N303) C, H, N.
`
`Notes
`
`Synthesis of Ethyl a-Acetamido-2-(pyrimid-2-yl)ac-
`etate (21). Using the preceding procedure and 20 (1.40 g, 6.4
`mmol), CHzClz (40 mL), Et3N (0.96 mL, 6.4 mmol), and AczO
`(0.92 g, 9.0 mmol) furnished 1.20 g (84%) of 21 as an oil: Rf
`0.21 (EtOAc); IR (neat) 3048, 2982, 1746, 1661, 1530, 1408,
`1275, 1020, 853, 787 cm-l; IH NMR (CDC13) 6 1.24 (t, J = 7.2
`Hz, OCHzC&), 2.12 (s, C(O)CHs), 4.23 (9, J = 7.2 Hz, OCH2-
`CH3),5.84(d, J=6.9Hz,CH),7.22(d, J = 6 . 9 H ~ , N H ) , 7 . 3 1
`(t, J = 4.8 Hz, CsH), 8.77 (d, J = 4.8 Hz, C3H and CeH); 13C
`NMR (CDCl3) 14.05 (OCHZCH~), 23.00 (C(O)CH3), 59.18 (CHI,
`62.19 (OCH2CH3), 120.42 (Cd, 157.62 (C4 and CS), 164.27 ((221,
`169.09 (C(O)CH3 or C(O)OCHzCH3), 169.80 (C(O)CH3 or
`C(0)OCHzCH3) ppm; MS, CI(+) (re1 intensity) 224 (M+ + 1,
`loo), 210 (88); M , (+CI) 224.10296 [M+ + 11 (calcd for
`C10H14N303 224.10352). Anal. (C10H13N303.0.35 HzO) C, H,
`N.
`Synthesis of a-Acetamido-N-benzyl-a-(pyrazin-2-y1)-
`acetamide (12). A methanolic (33 mL) solution o? 18 (2.60
`g, 11.7 mmol), benzylamine (1.50 g, 14.0 mmol), and NaCN1'
`(0.06 g, 1.2 mmol) was heated at reflux (2 d). The solvent was
`removed in vacuo, and the residue was purified by flash
`column chromatography on Si02 using 10% MeOWCHC13 as
`the eluant to give 1.80 g (54%) of 12. The product was
`recrystallized from EtOAc: mp 185-187 "C; Rf 0.25 (10%
`MeOWCHCl3); IR (KBr) 3052, 1744,1662, 1518, 1441, 1408,
`1375, 1236, 1148 cm-l; 'H NMR (DMs0-d~) 6 1.94 (s, C(0)-
`C&), 4.28 (d, J = 5.7 Hz, CH2), 5.69 (d, J = 7.8 Hz, CHI, 7.22-
`7.30 (m, 5 PhH), 8.58 (d, J = 2.5 Hz, C5H or CeH), 8.62 (d, J
`= 2.5 Hz, C5H or CsH), 8.72-8.75 (m, NH and C3H), 8.91 (t,
`J = 5.7 Hz, NH); 13C NMR (DMSO-de) 22.38 (C(O)CH3), 42.22
`(CHz), 56.49 (CH), 126.68 (C4'), 126.98 (2Ci or 2C3'), 128.14
`(2Ci or 2C3'), 138.90 (CI'), 143.74 (C3 and (25 and CS), 153.19
`(C2), 168.23 (C(O)CH3 or C(O)NH), 169.41 (C(O)CH3 or C(0)-
`NH) ppm; MS, CI(+) (re1 intensity) 285 (M+ + 1,461, 108 (100);
`M, (+CI) 285.13477 [M+ + 13 (calcd for C I ~ H I ~ N ~ O Z 285.13515).
`
`
`Anal. ( C I ~ H I ~ N ~ O Z ) C, H, N.
`Synthesis of a-Acetamido-N-benzyl-a-(pyrimid-2-y1)-
`acetamide (13). Using the previous protocol and methanol
`(150 mL), 21 (1.20 g, 5.4 mmol), benzylamine (0.69 g, 6.5
`mmol), and NaCN (0.06 g, 1.0 mmol) gave 1.00 g (64%) of 13:
`mp 174-176 "C; Rf 0.25 (10% MeOWCHC13); IR (KBr) 3059,
`2953,1750,1663,1543,1423,1381,1240,702 cm-l; 'H NMR
`(DMSO&) 6 1.94 (s, C(O)C&), 4.29 (d, J = 5.7 Hz, CH2), 5.68
`(d, J = 8.4 Hz, CH), 7.19-7.28 (m, 5 PhH), 7.44 (t, J = 4.8
`Hz, CsH), 8.52 (d, J = 8.4 Hz, NH), 8.80-8.82 (m, CJI, C6H
`and NH); 13C NMR (DMSOd6) 22.43 (CH3), 42.14 (CHz), 59.45
`(CH), 120.31 (CS), 126.56 (Ci), 126.90 (2Ci or 2C3'), 128.05
`(2C2' or 2C3'), 139.07 (Ci), 157.38 (C4 and CS), 165.75 (CZ),
`168.17 (C(O)CH3 or C(O)NH), 169.27 (C(OICH3 or C(0)NH);
`MS, CI(+) 285 (M+ + 1); M , (+CI) 285.13577 [M+ + 11 (calcd
`
`for C15H17N402 285.13515). Anal. ( C ~ ~ H ~ & O Z - O . ~ HzO) C, H,
`N.
`Synthesis of a-N-(DiphenylmethyleneW-benzyl-a-
`(pyrazin-2-y1)acetamide (22). A methanolic (2 mL) solution
`of 16 (0.50 g, 1.5 mmol), benzylamine (0.60 g, 5.8 mmol), and
`NaCN (0.01 g, 0.3 mmol) was heated to reflux (2 d). The
`solvent was removed in vacuo, and the residue was purified
`by flash column chromatography on Si02 using 66% ethyl
`acetatehexanes as the eluant to give 0.30 g (20%) of 22 as an
`oil: RfO.39 (66% ethyl acetatehexanes); IR (neat) 2978,2874,
`1746,1570,1504,1424,1373,1213,1057,855 cm-'; 'H NMR
`(CDCl3) 6 4.28 (d, J = 5.7 Hz, CH2), 5.31 (s, CHI, 6.92-7.67
`(m, 15 PhH), 7.84 (t, J = 5.7 Hz, MI), 8.40 (d, J = 2.4 Hz,
`C5H or CsH), 8.47 (d, J = 2.4 Hz, C5H or CsH), 8.53 (s, C3H);
`13C NMR (CDC13) 43.37 (CHz), 69.83 (CHI, 127.32, 127.46,
`127.57, 128.28,128.72, 128.89, 128.94, 129.34,131.16, 135.69,
`138.21,138.65 (3 C&,), 143.63 (C3 or CS or CS), 144.17 (C3 or
`C5 or CS), 144.47 (C3 or C5 or CS), 154.79 (CZ), 169.86 (C(N) or
`intensity) 407 (M+ + 1,351,239 (100); M, (+CI) 407.18636 [M+
`C(O)NH), 172.05 (C(N) or C(0)NH) ppm; MS, CI(+) (re1
`+ 11 (calcd for CzeH23N401 407.18719).
`Synthesis of a-Amino-2\r-benzyl-a-(pyrazin-2-yl)aceta-
`mide (23). Compound 22 (0.30 g, 0.9 mmol) was dissolved in
`Et20 (10 mL), and then an aqueous 1 N HC1 solution (1 mL,
`1.0 mmol) was slowly added and the mixture was stirred at
`room temperature (20 h). The layers were separated, and the
`
`IPR2014-01126- Exhibit 1034 p. 4
`
`

`
`Notes
`
`Journal of Medicinal Chemistry, 1994, Vol. 37, No. 26 4571
`
`aqueous layer was washed with Et20 (3 x 2 mL); the aqueous
`layer was kept, and the solvent was removed in vacuo. The
`residue was triturated with acetone to give 0.17 g (80%) of
`the hydrochloride salt, and then CHzClz (10 mL) and EtsN
`(0.06 g, 0.6 mmol) were added and the reaction mixture was
`stirred (1 h). The organic phase was washed with HzO (5 mL),
`dried (Na~S04), and concentrated in vacuo to give 0.14 g (100%)
`of 23 as an oil: Rf 0.45 (10% MeOWCHCls); IR (neat) 3426,
`'H
`3031, 2926, 1657, 1532, 1452, 1238, 1172, 978, 716 cm-';
`NMR (CD30D) 6 4.40 (s, CHd, 5.33 (8, CH), 7.21-7.44 (m, 5
`PhH), 8.70 (s, CKH and CsH), 8.88 (s, C3H); 13C NMR (CD3-
`OD) 44.25 (CH2), 54.14 (CH), 128.13 ((24'1, 128.32 (2Cz' or
`2C3'), 129.25, (2Ci or ~CS'), 138.80 (Cl'), 144.99 (CS or Cti or
`CS), 145.62 (Cs or Cs or C7), 146.36 (CS or C5 or CS), 149.10
`(Cd, 166.25 (C(0)NH) ppm; MS, CI(+) 243 (M+ + 1); M, (+CI)
`243.12455 [M+ + 11 (calcd for C ~ ~ H ~ K N ~ O I 243.12459).
`
`Synthesis of a-Acetamido-N-benzyl-a-(pyrazin-2-yl)-
`acetamide (12). To a CHzClz solution (1 mL) of 23 (0.03 g,
`0.1 mmol) was added AczO (0.02 g, 0.17 mmol), and the
`reaction mixture was stirred at room temperature (20 h). The
`solvent was removed in vacuo to give 0.03 g (99%) of the
`desired compound: mp 185-187 "C (mixed melting point with
`authentic material, 185-187 "C); Rf0.25 (10% MeOWCHC13);
`'H NMR (DMSO-de) 6 1.93 (9, C(O)C&), 4.28 (d, J = 5.7 Hz,
`CH2),5.71(d, J=7.8Hz,CH), 7.19-7.31(m,5PhH),8.59(d,
`J = 2.4 Hz, CKH or CsH), 8.62 (d, J = 2.4 Hz, CgH or CsH),
`8.70-8.73 (m, NH and C3H), 8.91 (t, J = 5.7 Hz, NH).
`Pharmacology. The compounds were tested under the
`auspices of the National Institutes of Health for anticonvulsant
`activity (phase I evaluation) using male Canvorth Farms No.
`1 mice. All compounds were given in three dose levels (30,
`100, and 300 mg/kg). Maximal electroshock seizures (MES)
`were then elicited with a 60-cycle alternating current of 50-
`mA intensity (5-7 times that which was necessary to elicit
`minimal electroshock seizures) delivered for 0.2 s via corneal
`electrodes. A drop of 0.9% saline was instilled in the eye prior
`to application of the electrodes so as to prevent the death of
`the animal. Protection in this test was defined as the abolition
`of the hind limb tonic extension component of the seizure. The
`effects of the compounds on forced and spontaneous motor
`activity were evaluated in mice by the rotorod test (tox). The
`animal was placed on an 1-in.-diameter knurled plastic rod
`rotating at 6 rpm affer the administration of the drug
`candidate. Normal mice can remain on a rod rotating at this
`speed indefinitely. Neurologic toxicity was defined as the
`failure of the animal to remain on the rod for 1 min. The MES
`test was conducted with a single animal, while four mice were
`utilized for the toxicology test. The dose-effect behavior
`(phase I1 quantitative evaluation) was evaluated by using the
`previously described procedures by the administration of
`varying dose levels of each compound, treating normally eight
`mice at each dose.
`
`Acknowledgment. We thank James P. Stables and
`the Anticonvulsant Screening Project (ASP) of the
`National Institute of Neurological and Communication
`Disorders and Stroke at the National Institutes of
`Health for kindly performing the pharmacological stud-
`ies. Funds for this project were provided in part by the
`State of Texas Advanced Technology Program.
`
`Supplementary Material Available: lH and I3C NMR
`spectra of compounds 14, 22, and 23 (6 pages). Ordering
`information is given on any current masthead page.
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`
`IPR2014-01126- Exhibit 1034 p. 5