P-4 光学活性Cyclobutanone誘導体の新規合成法の開発 : 複素環式天然化合物の不斉全合成への展開(ポスター発表の部)

抄録

A novel approach to chiral cyclobutanones has been developed by using asymmetric dihydroxylation(method A) and epoxydation(method B) of cyclopropylidene derivatives followed by concerted ring expansion of the resulted chiral diols and epoxides, respectively, as a key step. Although the former method A showed poor enantioselectivity, it was found that 1-hydroxymethylcyclobutanones(9) was obtained in high enantiomeric excess via the method B. Thus,a highly enantioselective total syntheses of (-)-mesembrine and (-)-ngaione, (+)-ipomeamarone and their epimers were achived through method B as a key step. The enantioselectivity in a synthesis of 1-aryl-1-hydroxymethylcyclo-butanone(27) through method B was also improved by examining the substituent effect of aryl part.