Highly Stereoselective α-Alkylations, 1,4-Additions, and One-pot 1,4-Addition/α-Methylations Achieved on 4-O-Acyl and 4-O-Crotonyl Derivatives of Methyl 6-Deoxy-2,3-di-O-(t-butyldimethylsilyl)-α-D-glucopyranoside
作者:Kiichiro Totani、Shingo Asano、Ken-ichi Takao、Kin-ichi Tadano
DOI:10.1055/s-2001-18107
日期:——
Benzylation or methylation of the enolate generated from 4-O-propionyl or 4-O-3-phenyl-propionyl derivatives of methyl 6-deoxy-2,3-di-O-(t-butyldimethylsilyl)-α-D-glucopyranoside provided the respective C-alkylated product stereoselectively. The 1,4-additions of a variety of carbon nucleophiles to the corresponding 4-O-crotonyl derivative provided adducts with high and complementary diastereoselection. The one-pot 1,4-additions of a phenyl nucleophile to the 4-O-crotonyl ester followed by the addition of methyl iodide provided vicinally substituted products with high diastereo- and enantioselectivity, from which diastereomeric α-methyl-β-phenylbutanols were obtained in enantioenriched form after reductive removal of the carbohydrate template.
对 6-脱氧-2,3-二-O-(叔丁基二甲基硅基)-δ±-D-吡喃葡萄糖苷甲基的 4-O-丙酰基或 4-O-3-苯基丙酰基衍生物生成的烯醇进行苄基化或甲基化,可立体选择性地提供相应的 C-烷基化产物。将各种碳亲核物与相应的 4-O-crotonyl 衍生物进行 1,4-加成,可提供具有高度非对映选择性和互补性的加合物。将苯基亲核剂与 4-O-crotonyl 酯进行单锅 1,4-加成,然后加入甲基碘,可得到具有高非对映选择性和对映体选择性的取代产物,在还原去除碳水化合物模板后,可得到对映体富集形式的δ-甲基δ-²-苯基丁醇。