Solution and Solid Phase Synthesis of Unusual a-Amino Acids From

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O occumd in high dia~tereoselectivity?~ The various factors influencing alkylation of 5.11 (P=Cbz, R'=~Bu, R~=M~) that were studied included temperature, solvent, various additives, concentration, ester protecting group, base and electrophile. The observed preference for anti alkylation in most of the previously descnbed syntheses by other groups was rationalized by chelation of the lithium counter-ion in a (2)-lithium ester enolate (discussed in more detail in section 5.2.5). 5.1.4.3 Other Methods for the Synthesis of flSubstiirued Aspartic Acidr Many methods exist for the synthesis of specific B-substituted aspartic acids that do not fit into the categories described above. (RB)-(+)-Tamate 5.15 was used to synthesize Lerythro-p-hydroxyaspartate (2S,3R) by selective protection and formation of triflate 5.16 which was then displaced with aide and reduced with H2S to give amine 5.17.M Subsequent deprotection/reprotection gave the desired product in 15% overall yield (Scheme 5.8). In 1990, Wagner et al. reported a modification of the tartrate method described above, which although gave lower yields the authors reported was more amenable to scale-upO6' The key step was a copper-mediated regioselective saponification of 5.17 and subsequent protection of the amine. Scheme 5.8
Garner's aldehyde 1.53 was also used to synthesize Lthreo-p-hydroxyaspartate (2S,3S) via an acetylenic intermediate which was oxidized to benzyl ester 5.18." The acetonide was then hydrolyzed to alcohol 5.19 that was oxidized to give the desired product in 12% overall yield (Scheme 5.9). MeOH., pTsOH Scheme 5.9 TMS 1) NaH, Bn0r , 2) NaOH 2) EnBr. K&03 Boc Boc Garner's aldehyde 1.53 has also been used in an asymrnetric [2+2] cycloaddition in a five step synthesis of protected 2R,3R-$-hydroxyaspartate (Scheme 5.10).63 The sarne group also reported a short synthesis of a variety of (2R,3R)-B-alkylated aspartates via P-Iactam 5.22 in high diastereoselectivity and good yield (Scheme 5.1 1 )? Scheme 5.10 - Boc XO - y OHC
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Solution and Solid Phase Synthesis
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The University of Waterloo requires
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Many people have made the experienc
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Table of Contents Abstract ........
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23 Summary ........................
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5.1.4.1 Enzymatic Methods .........
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List of Tables Table 2.1 Table 2.2
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Figure 4.1 O Figure 5.1 Figure 5.2
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CYS d DAST DBAD DBU DCC de DEAD dec
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NMP Nu OB0 ester PEG Ph Phe PhFl Ph
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1.1 General Introduction Chapter On
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acids will be presented including a
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.J generation of the enolate and ad
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classical techniques (Scheme 1.7) a
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s~ccess.~ The same principle has be
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O Scheme 1.11 O R1,qH2 m OH RI= H,
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stereosele~tivities.~ Numerous exam
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Williams and coworlcers have examin
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template, reaction with alkyl halid
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The 3-bromo analog of Williams and
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formation of serine aldehydes; dire
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Scheme 1.24 R dimethoxy- R ProPane
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of thiol trityl led to racemic cyst
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nucleophiles such as acetate and im
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may be employed, while the oxidatio
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Several methods for the removal of
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1.5 References Barrett, G.C. Chemis
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(a) Schmidt, U.; Meyer, R.; Leitenb
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R.M. Tetrahedron Le#. 2001,42, 769.
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(a) Lubell, W.D.; Rapport, H. J. Am
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Nakajima, K.; Takai, F.; Tanaka, T.
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2.1 Introduction Chapter Two Synthe
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2.1.1 Synthesis of SHydroxy-a-Amino
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typically generated in both poor yi
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2.1.3.3 Electrophilic%Nucfeophilic
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Scheme 2.8 2-(Arylthi0)-2-nitrooxir
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Scheme 2.10 Schollkopf et al. have
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2.1.3.5 Synthesis fiom #-Amino Acid
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HO Scheme 2.17 This laboratory prev
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Scheme 2.19 NaBr, acetone The best
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equires carefiil attention to preve
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order to investigate this as a poss
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etained its optical activity indica
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2.2.3.2 Ortho Ester Cleavage Concom
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2.2.4 Determination of Enantiomeric
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minof si face aîîack mior re face
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2.4.1 General Methods. Most reagent
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The crude product was fiitered thro
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250 MHz) 6 5.47 (br ci, lH, J = S.O
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evaporated to dryness. The residue
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minutes. The akohol solution was tr
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302.1604, found 302.1593; Anai. cal
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CCH3), 28.3 (a3)C), 20.1 (fLm3) 13.
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TLC (4: 1, CH2C12:EtOAc) Rf = 0.44;
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100-200 mesh, hydrogen form, 1x10 c
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(br d. IH. J= 10.6Hz, CHH-CH), 4.63
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mp 80-8 1 OC; [a~~*~a= -67.0 (0 1.5
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esin column (Bio-Rad AGa 10x4 10-20
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Jung, M.E.; Jung, Y.H. Tetruhedron
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(a) Adams, Z.M.; Jackson, R.F.W.; P
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(a) Roemmele, R.C.; Rapport, H. J.
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- - 68. Gawley, R.E.; Aubé, J. Pri
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pyridoxal phosphate dependent enzym
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Vinylglycines are also useful as sy
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In 1984, a modified Strecker synthe
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The main byproduct of elimination w
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, HO- OH Scheme 3.14 , 1) pb(OAc),
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L-vinylglycine has also been synthe
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Ser(a1d)-OB0 gave the desired olefi
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A tram relationship for H2IH3 in th
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33 Summary The Cbz OB0 ester protec
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67.1 (Ar_cH20), 63.2 @--a), 56.3 (a
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yielded a slightiy yellowish solid
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JAS Grigiarà ddition of trimethyls
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6 158.9 (CONH), 107.4 (OB0 ester C-
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Rutjes, F.P.J.T.; Wolf, L.B.; Schoe
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(a) Tashiro, T.; Fushiya, S.; Nome,
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Sawada, S.; Nakayama, T.; Esaki, N.
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of Rheum rhaponticum over forty yea
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Glutamic acid derivatives are aiso
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syntheses exist for the functionaii
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4.1.4 Synthesis of Optically Active
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4.1.4.3 Catalytic HydrogeMrion The
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Scheme 4.10 C02Et CO*Et R=Me, Et, P
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stereochemicaî induction at the re
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protected glutamate did not adopt a
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Scheme 4.16 The first synthesis of
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stereoselectivi ty during electroph
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kt, when we repeated the synthesis
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CbzH Scheme 4.2û OH pTsW CbzH Figu
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5.21 5.00 16.63 Figure 4.5: GCMS of
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Glu(y-Me)(OMe)OBO ester 4.73. Howev
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OB0 ester. Moreover, the stereochem
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Table 4.1: Optimilgtion of Methyiat
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Scheme 4.22 M'2aL O 2) 1) LiHMDS, P
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Table 4.2: Optimization of Hydroxyi
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Cb2H 1 OsO,. NMO acetone:H& OH m 2)
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The direct electrophilic azidizatio
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to the mesylate Alûû in 80% yield
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which were not isolated. ESI-MS and
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concentrateci reaction mixhue of 4.
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and during acid hydrolysis. HPLC an
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A general method for the synthesis
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Generai Procedure for Removd of Rot
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Same procedure as in 4.4.1. TU3 (1:
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Same procedure as in 4.4.3. [al% =
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ffom CH2Cl2) 3338,2962,2875, 1732,
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ester -0). 72.4 (OB0 ester w20), 65
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4m4.11 5-Methyl-(~,~-2-[(betl~gIo~)
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= l2JHz, CbzCHHO), 3.87-3.78 (s + r
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1016; HRMS (FAB) calcd for (M + H+)
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7.3&, CHZCH~), 0.78 (s, 3H, OB0 est
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hotu before benzyl brornide (0.21 m
Page 227 and 228: 1 H. J = 10.3Hz (detennined by deco
Page 229 and 230: 378.22; Anal. cdcd for CI9Ha07: C,
Page 231 and 232: (ça), 164.0 EONH), 143.3 (Cbz==).
Page 233 and 234: min. The solvent was removed under
Page 235 and 236: 173.8 c=O), 156.3 CONH), 137.6 ( Cb
Page 237 and 238: mp. 1 16- 1 165°C; [al2'D = -2 1 .
Page 239 and 240: (3:2 Et0Ac:hexanes) to give 4.99 (1
Page 241 and 242: Cbz-L-Glu(Z-B,y-dehydro)(OMe)OBO 49
Page 243 and 244: (CbzQI20), 57.4 (am, 39.8 (yCJS2),
Page 245 and 246: 3.7, 10.7, 14.5Hz. BCHH), 0.76 (S.
Page 247 and 248: TLC (1:1, EtOAc:Hex), Rc = 0.35; 'H
Page 249 and 250: 1515, 1227, 1048, 1016,909; ESI-MS
Page 251 and 252: (Cbz=@), 128.5, 128.2, 128.1 (a-=),
Page 253 and 254: TU3 ( 1 : 1, EtOAc:Hex), Rf = 0.17;
Page 255 and 256: 4-4-46 (2S,4S)-2-My14aminopentanedi
Page 257 and 258: give 0.020 g (54%) of the monoamrno
Page 259 and 260: 1. (a) Virtanen, A.I.; Berg, A.M. A
Page 261 and 262: Bory, S.; Dubois, J.; Gaudry, M.; M
Page 263 and 264: (a) Ezquerra, J.; Pedregal, C.; Ymr
Page 265 and 266: (a) Blaskovich, M.A.; Lajoie. G.A.
Page 267 and 268: Rathke, M-W.; Sullivan, D.F. J. Am,
Page 269 and 270: Chapter Five Stereoselective Synthe
Page 271 and 272: of p-methylaspartate 5.1 to glutama
Page 273 and 274: OAc Ac kfN&O@ 5.8 C02Et AC lU&02Et
Page 275 and 276: of 2:7 respectively, both of which
Page 277: MH). Changing the reaction conditio
Page 281 and 282: Rotected ~-aminoaspartate Sm6 was s
Page 283 and 284: amount of unreacted starting materi
Page 285 and 286: provided crystals of sufficient qua
Page 287 and 288: 5.2.2 Addition of Other AIkylation
Page 289 and 290: Scheme 5-18 We also investigated az
Page 291 and 292: 5.2.5 Discussion of the Stereochist
Page 293 and 294: face) to give rise to the B,3S ster
Page 295 and 296: The synthesis of threo-L-b-substitu
Page 297 and 298: TU3 (1: 1, CHC13:EtOAc, 1 % AcOH) R
Page 299 and 300: 156.0 (ÇONH), 1 36.2 (Cbz*), 128.5
Page 301 and 302: ester COI3), 30.6 (p-cH2), 14.1 (OB
Page 303 and 304: extracted with EtzO (3 x 25 d), the
Page 305 and 306: TU3 (1: 1, EtOAc:Hex), Rr = 0.48; '
Page 307 and 308: 63 MHz) 6 175.9 cd), 156.0 EONH), 1
Page 309 and 310: 175.1 CC-O), 155.8 (CONH), 136.1 (C
Page 311 and 312: 'H-NMR @20, 300 MHz) 6 7.26-7.03 (m
Page 313 and 314: 12.7Hz, CbzCHHO), 5.02 (ci, lH, J =
Page 315 and 316: TU3 ( 1 : 1, EtOAc:Hex), Rr = 0.40;
Page 317 and 318: 1. 2. 3. 4. 5. 6. 7. 8. 9. IO. 11.
Page 319 and 320: Eager, R.G. Jr.; Baltimore, B.G.; H
Page 321 and 322: - - Sardina, F.J.; Paz, MM.; Femihd
Page 323 and 324: Chapter Si Solid Phase Synthesis of
Page 325 and 326: eactions such as the Ugi condensati
Page 327 and 328: Dehydroamino acids have also been u
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Pyroglutarnate was reduced into the
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. - 6.2.1 Synthesis of Resin-Bod BH
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" 6.29 NMM, CH& Scheme 6.11 The arn
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esin placed hem Figure 6.3: Experim
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Figure 6.4: MAS 13c-N..~ (500 MHz)
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Table 6.1: Addition of R'M~B~ to 6.
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63 Summ Attachrnent of Ser-OB0 este
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(S. 2H, CbzCHzO), 4.57-4.40 (m, 7H,
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I C-O), 7 1.9 (OB0 ester GHzO), 61.
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insed, altemating with dry DMF (5 x
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- MAS 'H NMR (Spin-Echd ms): 8 3.87
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6.4.16 (zs)-2-Pmmo-3-hydroruy-3-met
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O.; Gilliarn, CL.; Boisclair, M.D.;
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38. Rakita, P.E.; Silverman, G.S. W
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of these important derivatives due
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the glutamate dimer. It may also be
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Rose, N.G.W.; Blaskovich, M.A.; Won
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Appendices
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Table 1, Cryatrl data and .tructuse
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Tabla 3. Bond langths [Al and amglr
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- - - . - Table 5. Eyârogen coordi
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Calculation of Free Energy Dinerenc
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Table 1. Crymtal data and mtructure
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. Tabla 3. Bond lenpths [il and rng
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X-Ray Crystallographic Data for Com
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4 Tabla 2. Atomic coordinates 1 x 1
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2 3 ? able 4. Aniiotsopic dfmplacea
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Calcdation to Determine Resin Loadi
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Solution and Solid Phase Synthesis of Unusual a-Amino Acids From

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