Phosphine-catalyzed synthesis of 1,3-dioxan-4-ylidenes.
[reaction: see text] A phosphine-catalyzed reaction of an allenoate with aldehydes furnished (2,6-diaryl-[1,3]dioxan-4-ylidene)-acetates 4 in excellent to moderate yields with complete diastereoselectivity and high E/Z-selectivities. Upon removal of the acetal functionality in this domino reaction product 4, delta-hydroxy-beta-ketoester 11 was obtained. The reported vinylphosphonium-based approach provides a new way to achieve a synthesis of delta-hydroxy-beta-ketoesters that differs from the classical dianion-based approach.
Zhu
Xue-Feng
XF
Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, USA.
Henry
Christopher E
CE
Wang
Jay
J
Dudding
Travis
T
Kwon
Ohyun
O