Direct Carbon-Carbon Bond Formation via Chemoselective Soft Enolization of Thioesters: A Remarkably Simple and Versatile Crossed-Claisen Reaction Applied to the Synthesis of LY294002
Guoqiang Zhou, Daniel Lim and Don M. Coltart*
*Department of Chemistry, Duke University, Durham, North Carolina 27708, Email: don.coltartduke.edu
G. Zhou, D. Lim, D. M. Coltart, Org. Lett., 2008, 10, 3809-3812.
DOI: 10.1021/ol801498u (free Supporting Information)
Thioesters undergo chemoselective soft enolization and acylation by N-acylbenzotriazoles on treatment with MgBr2ˇOEt2 and i-Pr2NEt to give β-keto thioesters without prior enolate formation. The reaction is conducted using untreated CH2Cl2 open to the air. The coupled products can be converted directly into β-keto esters, β-keto amides, and β-diketones under mild conditions.
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D. Lim, F. Fang, G. Zhou, D. M. Coltart, Org. Lett., 2007, 9, 4139-4142.
J. M. Yost, G. Zhou, D. M. Coltart, Org. Lett., 2006, 8, 1503-1506.