Asymmetric addition of n‐butyllithium to aldehydes by chiral polymers having acetoxybornyl moieties

Abstract

AbstractOptically active (+)‐2‐endo‐acetoxy‐5‐endo‐bornyl methacrylate (ABMA) was prepared from (+)‐camphor. The free‐radical homopolymerization of ABMA and its copolymerization with achiral methyl methacrylate (MMA) or styrene (St) were carried out with 2,2′‐azoisobutyronitrile in benzene. Effects of temperature and reaction time on the copolymerization were discussed. The monomer reactivity ratios (r1, r2) for poly(ABMA‐co‐MMA) and poly(ABMA‐co‐St) as well as Q and e values for the chiral ABMA in the copolymerization systems were evaluated by the Fineman‐Ross method. It was found that the absolute value of the specific rotation of poly(ABMA‐co‐MMA) increased with increasing ABMA unit content. A small deviation from linearity was observed, which suggests that asymmetry is not introduced into the copolymer main chain. Temperature and solvent effects on the specific rotation of the chiral homopolymer and copolymers were investigated. The results suggest that the chiral polymers synthesized in this investigation did not show a strong preference for a particular helical conformation. Applications of the chiral polymers on the asymmetric addition of n‐butyllithium to aldehydes were investigated. The effect of temperature and aldehydes on the asymmetric addition were also discussed.