Practical and robust method for regio- and stereoselective preparation of (E)-ketene tert-butyl TMS acetals and beta-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol ethers

Tomohito Okabayashi; Akira Iida; Kenta Takai; Yuuya Nawate; Tomonori Misaki; Yoo Tanabe

doi:10.1021/jo701456t

Practical and robust method for regio- and stereoselective preparation of (E)-ketene tert-butyl TMS acetals and beta-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol ethers

J Org Chem. 2007 Oct 12;72(21):8142-5. doi: 10.1021/jo701456t. Epub 2007 Sep 18.

Authors

Tomohito Okabayashi¹, Akira Iida, Kenta Takai, Yuuya Nawate, Tomonori Misaki, Yoo Tanabe

Affiliation

¹ Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.

PMID: 17877405
DOI: 10.1021/jo701456t

Abstract

We developed an efficient, practical, robust method for the regio- and stereoselective preparation of (E)-ketene trimethylsilyl acetals (KSAs) derived from tert-butyl esters 1. The reaction was performed under convenient reaction conditions; LDA-TMSCl, 0-5 degrees C, and cyclopentyl methyl ether (CPME) solvent. Two kinds of (Z)- and (E)-KSAs derived from alpha-oxygen and alpha-nitrogen-substituted tert-butyl esters, respectively, were also obtained in good yield. The present protocol was successfully applied to a stereocontrolled preparation of useful, but highly reactive (less accessible) beta-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol ethers 2.