光学活性フェロセンおよびその誘導体の新規合成法と不斉合成反応への応用

Abstract

A classical route to chiral ferrocenes is optical resolution of the racemate and limited compounds have been prepared by this method. Recent successes in the synthesis of a variety of chiral ferrocenes without optical resolution now have attracted considerable attention in asymmetric synthesis. The chiral ferrocenylalcohols, -amines, -acetals, and-oxazolines can be readily prepared from achiral acyl-, formylferrocenes, and ferrocenecarboxylic acids. These substituents attached to cyclopentadienyl group of ferrocenes are strong ortho directing groups which lead to planar chiral ferrocenes with highly regioselection (>99% de). The planar chiral ferrocene can be also prepared by enantioselective lithiation of the achiral ferrocenylamide and amine with the chiral lithium reagent. C2 symmetrical 1, 1'-ferrocenediol is obtained from asymmetric reduction of 1, 1'-diacyl ferrocene and can be converted to the corresponding ferrocenediamine and-diphosphine derivatives. New planar chiral ferrocenyl phosphines and alcohols are examined in the benchmark asymmetric allylic substitution and dialkylzinc addition to an aldehyde, respectively.