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Enantioselective Synthesis of Allenes by Catalytic Traceless Petasis Reactions

Yao Jiang, Abdallah B. Diagne, Regan J. Thomson* and Scott E. Schaus*

*Department of Chemistry, Northwestern University, Evanston, Illinois 60208; Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States, Email: r-thomsonnorthwestern.edu, seschausbu.edu

Y. Jiang, A. B. Diagne, R. J. Thomson, S. E. Schaus, J. Am. Chem. Soc., 2017, 139, 1826-1829.

DOI: 10.1021/jacs.6b11937 (free Supporting Information)



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Abstract

An asymmetric boronate addition to sulfonyl hydrazones catalyzed by chiral biphenols provides enantioenriched allenes in a traceless Petasis reaction. The resulting Mannich product from nucleophilic addition eliminates sulfinic acid, yielding a propargylic diazene that performs an alkyne walk to afford the allene. Two enantioselective approaches have been developed for the synthesis of allylic hydroxyl allenes and 1,3-alkenyl allenes.

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Development of an enantioselective allene synthesis reaction. Asymmetric routes to chiral allenes from (A) alkynyl boronate addition to glycolaldehyde imine and (B) allylation of alkynyl hydrazones.



A Direct Synthesis of Allenes by a Traceless Petasis Reaction

D. A. Mundal, K. E. Lutz, R. J. Thomson, J. Am. Chem. Soc., 2012, 134, 5782-5785.


Key Words

Petasis Reaction, allenes, 1,4-dienes


ID: J48-Y2017