Synlett 2008(15): 2231-2243  
DOI: 10.1055/s-2008-1077971
ACCOUNT
© Georg Thieme Verlag Stuttgart ˙ New York

Torquoselective Olefination of Carbonyl Compounds with Ynolates: Highly Efficient Stereoselective Synthesis of Tetrasubstituted Alkenes

Mitsuru Shindo*a, Seiji Morib
a Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasugakoen, Kasuga 816-8580, Japan
Fax: +81(92)5837875; e-Mail: shindo@cm.kyushu-u.ac.jp;
b Faculty of Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
Further Information

Publication History

Received 26 February 2008
Publication Date:
15 July 2008 (online)

Abstract

The torquoselectivity-controlled olefination of carbonyl compounds with ynolates affording tetrasubstituted alkenes is described. The E/Z selectivity is determined in the step consisting of electrocyclic ring opening of the β-lactone enolates (oxetenes) derived from cycloaddition of ynolates with carbonyl compounds. Theoretical calculations revealed that several secondary orbital interactions are critical for the high torquoselectivity. This methodology is a novel olefination for constructing multisubstituted olefins.

1 Introduction

2 Preparation of Ynolates

3 Olefination of Aldehydes

4 Olefination of Unfunctionalized Ketones

5 Acylsilanes and Acylgermanes

5.1 Olefination of Acylsilanes

5.2 Olefination of Acylgermanes

5.3 Olefination of Acylsilanes and Acylgermanes via Stereo­selective Protonation of β-Lactone Enolates, Followed by Decarboxylation

5.4 Organic Synthesis Using Multisubstituted Vinylsilanes

5.4.1 Oxidative Cleavage of C-Si Bonds

5.4.2 Reactions of Silalactones

5.4.3 Palladium-Catalyzed Cross Coupling Activated by Hypervalency

6 Heteroatom-Directed Torquoselective Olefination

7 Olefination of Esters

8 Olefination of Aldimines

9 Conclusion