1,4‐Pentenyne as a Five‐Carbon Synthon for Efficient and Selective Syntheses of Natural Products Containing 2,4‐Dimethyl‐1‐penten‐1,5‐ylidene and Related Moieties by Means of Zr‐Catalyzed Carboalumination of Alkynes and Alkenes

Abstract

Two highly efficient protocols for enantioselective synthesis of 2,4-dimethyl-1-penten-1,5-ylidene derivatives involve the combined use of the Zr-catalyzed methylalumination of alkynes (ZMA) and the Zr-catalyzed asymmetric carboalumination of alkenes (ZACA). The ZMA/ZACA protocol has been applied to the synthesis of a nafuredin intermediate 14 and a potential intermediate 18 for milbemycin beta 3, while the ZACA/ZMA protocol has been applied to the synthesis of a (-)-bafilomycin A(1) intermediate 25.