A concise construction of carbohydrate-tethered axially chiral allenes via copper catalysis

Abstract

The efficient construction of the axial chirality of allenes bearing a carbohydrate unit is challenging. Here we observed that the newly developed CuBr₂ catalysis may smoothly catalyze the highly diastereoselective three-component reaction of carbohydrates bearing a terminal alkyne unit, aliphatic or aromatic aldehydes, and (R) or (S)-α,α-diphenylprolinol, affording carbohydrates bearing the chiral 1,3-substituted allene entity in very high de (94–99%). Synthetically attractive functionalities, such as hydroxyl, amide, malonate, and even tosylate, etc. could all be well tolerated. The role of the carbohydrate unit has been explored.