Boc-L-天冬酰胺-L-脯氨酸苄酯·甲醇与脱水副产物Boc-β-氰基-L-丙氨酸-L-脯氨酸苄酯的合成及晶体结构
Synthesis and crystal structures of Boc-L-Asn-L-Pro-OBzl.CH3OH and dehydration side product, Boc-beta-cyano-L-alanine-L-Pro-OBzl.
作者信息
Stroup A N, Cole L B, Dhingra M M, Gierasch L M
机构信息
Department of Biochemistry, Howard Hughes Medical Institute, Dallas, Texas.
出版信息
Int J Pept Protein Res. 1990 Dec;36(6):531-7. doi: 10.1111/j.1399-3011.1990.tb00992.x.
Boc-L-Asn-L-Pro-OBzl: C21H29O6N3.CH3OH, Mr = 419.48 + CH3 OH, monoclinic, P2(1), a = 10.049(1), b = 10.399(2), c = 11.702(1) A, beta = 92.50(1)degrees, V = 1221.7(3) A3, dx = 1.14 g.cm-3, Z = 2, CuK alpha (lambda = 1.54178 A), F(000) = 484 (with solvent), 23 degrees, unique reflections (I greater than 3 sigma(I)) = 1745, R = 0.043, Rw = 0.062, S = 1.66. Boc-beta-cyano-L-alanine-L-Pro-OBzl: C21H27O5N3, Mr = 401.46, orthorhombic, P2(1)2(1)2(1), a = 15.741(3), b = 21.060(3), c = 6.496(3) A, V = 2153(1) A3, dx = 1.24 g.cm-3, Z = 4, CuK alpha (lambda = 1.54178 A), F(000) = 856, 23 degrees, unique reflections (I greater than 3 sigma(I)) = 1573, R = 0.055, Rw = 0.078, S = 1.86. The tert.-butyloxycarbonyl (Boc) protected dipeptide benzyl ester (OBzl), Boc-L-Asn-L-Pro-OBzl, prepared from a mixed anhydride reaction using isobutylchloroformate, Boc-L-asparagine, and HCl.L-proline-OBzl, crystallized with one methanol per asymmetric unit in an extended conformation with the Asn-Pro peptide bond trans. Intermolecular hydrogen bonding occurs between the methanol and the Asn side chain and between the peptide backbone and the Asn side chain. A minor impurity due to the dehydration of the Asn side chain to a beta-CNala crystallized with a similar extended conformation and a single intermolecular hydrogen bond.
叔丁氧羰基-L-天冬酰胺-L-脯氨酸苄酯：C21H29O6N3·CH3OH，Mr = 419.48 + CH3OH，单斜晶系，P2(1)，a = 10.049(1)，b = 10.399(2)，c = 11.702(1) Å，β = 92.50(1)°，V = 1221.7(3) Å3，dx = 1.14 g·cm-3，Z = 2，CuKα（λ = 1.54178 Å），F(000) = 484（含溶剂），23°，独立反射（I > 3σ(I)） = 1745，R = 0.043，Rw = 0.062，S = 1.66。叔丁氧羰基-β-氰基-L-丙氨酸-L-脯氨酸苄酯：C21H27O5N3，Mr = 401.46，正交晶系，P2(1)2(1)2(1)，a = 15.741(3)，b = 21.060(3)，c = 6.496(3) Å，V = 2153(1) Å3，dx = 1.24 g·cm-3，Z = 4，CuKα（λ = 1.54178 Å），F(000) = 856，23°，独立反射（I > 3σ(I)） = 1573，R = 0.055，Rw = 0.078，S = 1.86。由异丁基氯甲酸酯、叔丁氧羰基-L-天冬酰胺和盐酸-L-脯氨酸苄酯通过混合酸酐反应制备的叔丁氧羰基（Boc）保护的二肽苄酯（OBzl），Boc-L-天冬酰胺-L-脯氨酸苄酯，每个不对称单元含一个甲醇结晶，呈伸展构象，天冬酰胺-脯氨酸肽键为反式。甲醇与天冬酰胺侧链之间以及肽主链与天冬酰胺侧链之间存在分子间氢键。由于天冬酰胺侧链脱水形成β-CNala产生的少量杂质以类似的伸展构象和单个分子间氢键结晶。
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