Boron Tribromide‐Assisted Chiral Phosphoric Acid Catalysts for Enantioselective [2+2] Cycloaddition

Tatsuhiro Sakamoto; Takuya Mochizuki; Yuta Goto; Manabu Hatano; Kazuaki Ishihara

Index: 10.1002/asia.201800351

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Abstract

BBr3‐assisted chiral phosphoric acid catalysts for enantioselective [2+2] cycloaddition were developed. The reactions of phenyl vinyl sulfide with α‐substituted acroleins proceeded, and the corresponding [2+2] cycloadducts were obtained with high enantioselectivity. In particular, the [2+2] cycloadduct obtained from methacrolein was a synthetically useful optically active cyclobutane, which could be transformed to a key intermediate for (+)‐frontalin, a pheromone of Asian elephants.