Highly Selective Manganese(I)/Lewis Acid Cocatalyzed Direct C−H Propargylation Using Bromoallenes

Abstract

A manganese(I)/Lewis acid cocatalyzed direct C-H propargylation with high selectivity has been developed. BPh₃ was discovered to not only promote the reactivity, but also enhance the selectivity. Secondary, tertiary, and even quaternary carbon centers at the propargylic position could be directly constructed. Both internal and terminal alkynes are easily accessible. The chirality was successfully transferred from an axially chiral allene to central chirality. The reactivity of the manganese catalyst in this reaction was found to be unique among transition metal catalysts.