corresponding hemiacetals which, by choice of hydride reagents, can be reduced stereoselectively to give products with a syn-(threo-) relationship between the new chiral centre and that at C-2 of the lactone.
有机镁和/或
有机锂试剂与 2,3-O-异亚丙基-D-赤藓内酯和 5-O-叔丁基二苯基甲
硅烷基 1-2,3-O-异亚丙基-
D-核糖内酯的反应得到了相应的
半缩醛的良好产率,通过
氢化物试剂的选择,可以立体选择性地还原以产生在新手性中心和内酯的 C-2 之间具有顺式(苏式)关系的产物。