1,2-cis Alkyl glycosides: straightforward glycosylation from unprotected 1-thioglycosyl donors

Abstract

A 1,2-cis-alkyl glycosidation protocol that makes use of unprotected phenyl 1-thioglycosyl donors is reported. Glycosylation of various functionalized alcohols was accomplished in moderate to high yield and selectivity to give the 1,2-cis-glycosides. In order to quickly develop optimum glycosylation conditions, an FIA (flow injection analysis)-ESI-TOF-MS method was developed that enabled rapid and quantitative evaluation of yield on small scale. This methodology, coupled with NMR spectroscopy, allowed for rapid evaluation of the overall reactions.

Photoinduced Thiol‐ene Chemistry Applied to the Synthesis of Self‐Assembling Elastin‐Inspired Glycopeptides

“…The organic phase was dried over MgSO 4 and condensed 2 b as a white solid (360 mg, 94 %). 1 H NMR spectroscopic analysis of 2 b returned signals in full agreement with literature reference …”

“…1 HNMR spectroscopic analysis of 2b returned signals in full agreement with literature reference. [30] Allyl 2,3,4,5-tetra-O-acetyl-a-d-mannopyranoside (2 c) 2c was prepared from allyl a-d-mannopyranoside 1c (110 mg, 0.5 mmol) according to the procedure for 2b (180 mg, 94 %y ield). 1 HNMR spectroscopic analysis of 2c returned signals in full agreement with literature reference.…”

Stereocontrolled 1,2-cis glycosylation as the driving force of progress in synthetic carbohydrate chemistry

“…Glycosidation of unprotected glycosyl donors with reactive glycosyl acceptors proceeding with good to excellent 1,2- cis stereoselectivity has also been reported. 34 …”

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

“…The protecting-group-free glycosylation at first glance looks like a nearly impossible task, but the inherent different reactivity of the reducing end of a saccharide unit is fascinating, and even more interesting is the creative ways modern chemists are exploiting it. It is truly groundbreaking that Lewis acid-mediated [56–57] and transition-metal-catalyzed [62,65] strategies are feasible even with other reactive groups present on the donor molecule and that access to the always challenging 1,2- cis glycosides are available by employing a remote activation strategy [42–43 49–50]. We acknowledge the incredibly operationally simple C3′–OH regioselective glycosylation of sucrose as particularly fascinating [57].…”

“…3.3.1 Access of 1,2- cis glycosides: A potentially attractive strategy for a 1,2- cis glycosylation has been described by Baker and colleagues [56] and employs the use of a deprotected thiol glycoside in the presence of a large excess of Lewis acid (TMSOTf) and N -iodosuccinimide (NIS). Although the stereoselectivity of the reaction is noteworthy and the study extensive (Fig.…”