ortho-Amide-directed 2,4-dibromohydration of conjugated enynes

Abstract

In this work, a NBS-mediated 2,4-dibromohydration of enynes is described. It has been proved that ortho-acetamide participated in this 2,4-dibromohydration process. Mechanism studies show that an amide oxygen transfers into enynes to form a carbonyl of the products. One equivalent of water is incorporated into the ortho-acetamide group. The reaction proceeds smoothly with good functional tolerance and efficiency. Interestingly, the structural elaboration is also realized when NaBH₄ is employed.