Pd(OAc)2-Catalyzed Cyclization of 2,3-Allenoic Acids in the Presence of Terminal α,β-Unsaturated Alkynones: A One-Pot Highly Stereoselective Synthesis of 4-(3′-Oxo-1′(E)-alkenyl)-2(5H)-furanones
摘要:
The Pd(OAc)(2)-catalyzed cyclization reaction of 2,3-allenoic acids in the presence of terminal alpha,beta-unsaturated alkynones afforded an E/Z mixture of 4-(3'-oxo-1'-alkenyl)-2(5H)-furanones. A subsequent complete isomerization of the Z-isomer to E-isomer was observed in DMSO at 90 degrees C, which led to a highly stereoselective synthesis of 4-(3'-oxo-1'(E)-alkenyl)-2(5H)-furanones. A possible mechanism is proposed.