The stereoselectivity of the alkylation of the dianion of ethyl 2-hydroxy-6-methylcyclohexanecarboxylates: Control of stereochemistry at three adjacent stereogenic centers
作者:Georg Fráter、Wulf Günther、Urs Müller
DOI:10.1002/hlca.19890720821
日期:1989.12.13
Yeast reduction of rac-ethyl 2-methyl-6-oxocylohexanecarboxylate (rac-1) yielded selectively (+)-ethyl 2-hydroxy-6-methylcyclohexane carboxylate (+)-2 (Scheme 1) which has been alkylated with 5-iodo-2-methylbut-2-ene by (the dianion method to furnish the 4-methylbut-3-enyl derivat 3 (Scheme 3)). NaBH4 reduction of (+)-1 led to three hydroxy-carboxylates (−)-2, (+)-5, and (−)-6 (Scheme 4). Allylation
的酵母还原外消旋-乙基2-甲基-6- oxocylohexanecarboxylate(外消旋- 1)选择性地得到(+) - 2-羟基-6-甲基环己烷羧酸酯(+) - 2(方案1),其已被烷基化,5-碘通过(二价阴离子法提供4-甲基丁-3-烯基衍生物3(方案3),得到-2-甲基丁-2-烯)。NaBH 4(+)- 1的还原导致生成三个羟基羧酸盐(-)- 2,(+)- 5和(-)- 6(方案4)。(+)- 5的二价阴离子的烯丙基化得到(+)- 7。