Synlett 2017; 28(10): 1121-1126
DOI: 10.1055/s-0036-1588722
synpacts
© Georg Thieme Verlag Stuttgart · New York

2,6-Lactones as a New Entry in Stereoselective Glycosylations

Kaname Sasaki*
Department of Chemistry, Toho University, 2-2-1 Miyama, Funabashi 274-8510, Japan   Email: kaname.sasaki@sci.toho-u.ac.jp
,
Yusuke Hashimoto
Department of Chemistry, Toho University, 2-2-1 Miyama, Funabashi 274-8510, Japan   Email: kaname.sasaki@sci.toho-u.ac.jp
› Author Affiliations
Further Information

Publication History

Received: 27 December 2016

Accepted after revision: 24 January 2017

Publication Date:
23 February 2017 (online)


Abstract

The advantages of glycosyl donors bearing a 2,6-lactone moiety in 1,2-cis-β-glycosylation reactions are discussed in the context of recent comprehension on the SN2–SN1 borderline. The 2,6-lactone structure increases the likelihood of the SN2-like reaction, analogous to 4,6-tethered structures or 2-O-electron-deficient substituents, which are known to mound the energetic barrier to SN1 reactions. Furthermore, the glycosyl cation generated from the 2,6-lactone donor seems to direct β-glycosides similar to the torsional and flipped cations generated from 4,6-tethered donors and mannuronate or 3,6-lactone donors, respectively. Overall, 2,6-lactones are suitable for use in 1,2-cis-β-glycosylations, and this novel class of donors is expected to help deepen our global understanding of glycosylation reactions.

1 Introduction

2 Stereoinversion (SN2-Like) Reactions

3 Conformational Control of Glycosyl Cations

4 Conclusions