Imperio D, Brentazzoli M, Valloni F, Minassi A, Panza L. Iodine-triphenylphosphine triggers an easy one-pot alpha stereoselective dehydrative glycosylation on hemiacetalic benzylated glycosyl donors.
Carbohydr Res 2023;
533:108944. [PMID:
37729855 DOI:
10.1016/j.carres.2023.108944]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/11/2023] [Accepted: 09/13/2023] [Indexed: 09/22/2023]
Abstract
The discovery of new glycosylation reactions is still a major challenge in carbohydrate chemistry. Traditional glycosylation reactions require the preparation of sugar donors with anomeric active or latent leaving groups. Dehydrative glycosylation is a fascinating alternative that enables the direct formation of the glycosidic bond from the hemiacetal, eliminating the need for (sometimes unstable) leaving groups, and allowing to reduce reaction, work-up, and purification times. Although some interesting methods of dehydrative glycosylation have been reported, in order to compete with conventional chemical glycosylation, a greater number of efficient and stereoselective methods need to be developed. Herein, a dehydrative procedure that uses a combination of iodine, triphenylphosphine, and a base (DMAP or imidazole) is described. This methodology allows for the preparation of sugar derivatives from commercially available 1-hydroxy glycosyl donors. The reaction takes place under mild conditions through the in situ-formation of an anomeric iodide intermediate, which, upon reaction with an alcohol, gives the corresponding glycosides up to quantitative yields and with high α-stereoselectivity.
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