Very efficient enantioselective syntheses of (1R)--and -hemicaronaldehydes precursors of (1R)-trans chrysanthemic acid and its (1R)-cis dibromovinyl analogue starting from natural tartaric acid or D-mannitol are described. They are based on the reaction between isopropylidenetriphenylphosphorane or isopropylidenediphenylsulfurane and chiral γ-alkoxy-α,β-unsaturated esters. The general problem of the
描述了从天然
酒石酸或
D-甘露糖醇开始的(1R)-反式
菊酸的(1R)-和-半甲基
乙醛前体及其(1R)-顺式二
溴乙烯基类似物的非常有效的对映选择性合成。它们基于异丙基亚丙基
三苯基膦或异丙基二烯基二苯基
硫磺与手性γ-烷氧基-α,β-不饱和酯之间的反应。讨论了将非对映选择性加成到这些酯中的一般问题。