(629c) Self-Assembly of Achiral Surfactants Can Conduct Enantioselective C-C Bond Formation of Amino Acid Derivative

The use of achiral surfactant assemblies as a reaction platform for an alkylation reaction resulted in a high enantiomeric excess. Dilauryldimethylammonium bromide (DDAB) vesicles were modified with cholesterol to promote alkylation of N-(diphenylmethylene)glycine tert-butyl ester (DMGBE) with benzyl bromide, resulting in high conversion (∼90%) and high enantioselectivity (up to 80%) [1]. The R-enantiomer was formed on using the DDAB vesicles, whereas the use of phospholipid liposomes prepared from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) produced an excess of the S-enantiomer [2]. Considering the chemical structures of the reaction substrates and amphiphiles as well as the membrane structures and properties of DDAB vesicles and DOPC liposomes, it is suggested that the enantiomeric excesses result from the location of the quaternary amine of the amphiphiles and the DMGBE at the outer surface of the membrane. We show that the enantioselective reaction at the surface of the self-assembly could be regulated by adjusting the chemical structures and resulting membrane properties of the self-assembly.

[1] F. Iwasaki et al., Enantioselective C—C Bond Formation Enhanced by Self-Assembly of Achiral Surfactants. ACS Omega, 2017, 2 (4), 1447–1453.　[2] F. Iwasaki et al., Liposomes Can Achieve Enantioselective C–C Bond Formation of an α-Amino Acid Derivative in Aqueous Media. ACS Omega, 2017, 2 (1), 91–97.