Synthesis 2016; 48(23): 4072-4080
DOI: 10.1055/s-0035-1562482
paper
© Georg Thieme Verlag Stuttgart · New York

A General and Robust Method for the Preparation of (E)- and (Z)-Stereodefined Fully Substituted Enol Tosylates: Promising Cross-Coupling Partners

Yuichiro Ashida
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
,
Yuka Sato
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
,
Atsushi Honda
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
,
Hidefumi Nakatsuji*
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
,
Yoo Tanabe*
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan   Email: tanabe@kwansei.ac.jp
› Author Affiliations
Further Information

Publication History

Received: 10 May 2016

Accepted after revision: 04 July 2016

Publication Date:
15 August 2016 (online)


Abstract

A robust method for preparing (E)- and (Z)-stereodefined fully substituted enol tosylates is described. α-Substituted β-keto esters undergo (E)-selective enol tosylations using TsCl–Me2N(CH2)6NMe2 as the reagent (method A, 13 examples; 63–96%) and (Z)-selective enol tosylations using TsCl–TMEDA–LiCl as the reagent (method B, 13 examples; 62–99%). A plausible mechanism for the (E)- and (Z)-enol tosylation selectivity is proposed. A 1H NMR monitoring experiment revealed that TsCl coupled with TMEDA formed a simple N-sulfonylammonium intermediate.

Supporting Information

 
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