Valenteković S, Keglević D
Carbohydr Res. 1976 Mar;47(1):35-48. doi: 10.1016/s0008-6215(00)83546-6.
Catalytic hydrogenation of 2,3,4,6-tetra-O-benzyl-1-O-[1-benzyl N-(benzyloxycarbonyl)-L-aspart-4-oyl]-alpha-D-glucopyranose (1alpha) in acetic acid-2-methoxyethanol gave 1-O-(L-beta-aspartyl)alpha-D-glucopyranose (2alpha) contaminated with 2-O-(L-alpha-aspartyl)-D-glucopyranose (8). Evidence that 8 was formed from the 1-oyl isomer of 1alpha, namely 2,3,4,6-tetra-O-benzyl-1-O-[4-benzyl N-(benzyloxycarbonyl)-L-aspart-1-oyl]-alpha-D-glucopyranose (7alpha), via 1 leads to 2 acyl migration, was obtained by submitting the deprotected D-glucosyl ester to successive N-acetylation, esterification, and O-acetylation; the final product was identified as a approximately 4:1 mixture of 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(acetyl)-L-aspart-4-oyl]-alpha-D-glucopyranose (4alpha) and 1,3,4,6-tetra-O-acetyl-2-O-[4-methyl N-(acetyl)-L-aspart-1-oyl]-D-glucopyranose (6) which were also prepared by definitive methods. On the other hand, deprotection of 1beta gave isomerically pure 2beta which was converted into the peracetylated ester derivative 4beta; an explanation for the differences in aglycon isomeric purity of 2alpha and 2beta is given. Hydrogenolysis of 7beta under the above conditions led to intermolecular transesterification with scission of the C-1 ester bond to give 1-(2-methoxyethyl) L-aspartic acid and D-glucose. Catalytic hydrogenation of 7alpha and 7beta, performed in the presence of trifluoroacetic acid, afforded 1-O-(L-alpha-aspartyl)-alpha- and -beta-D-glucopyranoside trifluoroacetate salts (11alpha and 11beta), respectively. The structure of 11beta was established by successive conversion into 2,3,4,6-tetra-O-acetyl-1-O-[4-methyl N-(acetyl)-L-aspart-1-oyl]-beta-D-glucopyranose (5beta) which was also prepared by definitive methods. Analogous treatment of 11alpha gave the N-acetyl derivative 12 which underwent 1 leads to 2 acyl migration during esterification with diazomethane to give the N-acetyl methyl ester derivative 10; acetylation of 10 afforded 6.
在乙酸 - 2 - 甲氧基乙醇中对2,3,4,6 - 四 - O - 苄基 - 1 - O - [1 - 苄基 - N -（苄氧羰基）- L - 天冬氨酰 - 4 - 酰基] - α - D - 吡喃葡萄糖（1α）进行催化氢化反应，得到被2 - O -（L - α - 天冬氨酰）- D - 吡喃葡萄糖（8）污染的1 - O -（L - β - 天冬氨酰）α - D - 吡喃葡萄糖（2α）。有证据表明8是由1α的1 - 酰基异构体，即2,3,4,6 - 四 - O - 苄基 - 1 - O - [4 - 苄基 - N -（苄氧羰基）- L - 天冬氨酰 - 1 - 酰基] - α - D - 吡喃葡萄糖（7α），通过1导致2酰基迁移而形成的，这是通过对脱保护的D - 葡萄糖基酯进行连续的N - 乙酰化、酯化和O - 乙酰化得到的；最终产物被鉴定为2,3,4,6 - 四 - O - 乙酰基 - 1 - O - [1 - 甲基 - N -（乙酰基）- L - 天冬氨酰 - 4 - 酰基] - α - D - 吡喃葡萄糖（4α）和1,3,4,6 - 四 - O - 乙酰基 - 2 - O - [4 - 甲基 - N -（乙酰基）- L - 天冬氨酰 - 1 - 酰基] - D - 吡喃葡萄糖（6）的约4:1混合物，它们也通过确定的方法制备。另一方面，1β的脱保护得到了异构体纯的2β，其被转化为全乙酰化酯衍生物4β；给出了2α和2β苷元异构体纯度差异的解释。在上述条件下对7β进行氢解导致分子间酯交换并断裂C - 1酯键，得到1 -（2 - 甲氧基乙基）L - 天冬氨酸和D - 葡萄糖。在三氟乙酸存在下对7α和7β进行催化氢化反应，分别得到1 - O -（L - α - 天冬氨酰）- α - 和 - β - D - 吡喃葡萄糖苷三氟乙酸盐（11α和11β）。11β的结构通过连续转化为2,3,4,6 - 四 - O - 乙酰基 - 1 - O - [4 - 甲基 - N -（乙酰基）- L - 天冬氨酰 - 1 - 酰基] - β - D - 吡喃葡萄糖（5β）得以确定，5β也通过确定的方法制备。对11α进行类似处理得到N - 乙酰基衍生物12，其在与重氮甲烷酯化过程中发生1导致2酰基迁移，得到N - 乙酰基甲酯衍生物10；10的乙酰化得到6。
