新規ピペラジン型キラルジアミンの分子設計及びその銅錯体を用いたメゾ型1,2-ジオールの不斉アシル化

抄録

We present an efficient synthesis of a novel class of alicyclic chiral diamine DHPP and DMPP from L-proline, and their application to the asymmetric acylation of meso-1,2-diols catalyzed by chiral diamine–cupric chloride. One pot esterification of L-proline followed by dimerization gave corresponding diketopiperazine. Monomethylation of diketopiperazine was performed by Romo's procedure using KHMDS–iodomethane, and second methylation was conducted by lithium diethylamide–iodomethane to give cis-dimethyldiketopiperazine as sole diastereomer. Finally, diketopiperazine and dimethyldiketopiperazine were reduced by lithium aluminum hydride to give DHPP and DMPP. Asymmetric benzoylation of all meso-1,2-diols investigated was achieved in high enantioselectivity with CuCl₂–DMPP complex, while use of CuCl₂–bisoxazoline complex exhibited relatively low optical yield.

Scheme 1