General, robust, and stereocomplementary preparation of alpha,beta-disubstituted alpha,beta-unsaturated esters
Hidefumi Nakatsuji1, Hiroshi Nishikado, Kanako Ueno
1Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
Abstract:
An (E)- and (Z)-stereocomplementary preparative method for alpha,beta-disubstituted alpha,beta-unsaturated esters is performed via three general and robust reaction sequences: (i) Ti-Claisen condensation (formylation) of esters to give alpha-formyl esters (12 examples, 60-99%), (ii) (E)- and (Z)-stereocomplementary enol p-toluenesulfonylation (tosylation) using TsCl-N-methylimidazole (NMI)-Et(3)N and LiOH (24 examples, 82-99%), and (iii) stereoretentive Suzuki-Miyaura cross-coupling (18 examples, 64-96%).
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