1169827-79-5Relevant academic research and scientific papers
Protecting Group Dependence of Stereochemical Outcome of Glycosylation of 2-O-(Thiophen-2-yl)methyl Ether Protected Glycosyl Donors
Watson, Andrew J. A.,Alexander, Stewart R.,Cox, Daniel J.,Fairbanks, Antony J.
, p. 1520 - 1532 (2016/04/05)
A series of glycosyl donors possessing a (thiophen-2-yl)methyl ether protecting group at position 2 were synthesised and the effect of the protecting group pattern of other hydroxyls on the stereochemical outcome of glycosylation was investigated. Studies revealed optimal α-selectivity for glycosylation using a fully armed tri-benzylated donor, whilst other protecting group patterns were significantly less effective. Low-temperature NMR studies of both fully armed and fully disarmed donors revealed the intermediacy of cyclised sulfonium ion intermediates. Reaction conditions were developed which allowed removal of the (thiophen-2-yl)methyl ether protecting group either selectively, or together with benzyl ethers. Glycosyl donors with a 2-O-thiophenylmethyl ether protecting group undergo six-membered ring NGP, as demonstrated by low-T NMR studies, but the stereochemical outcome of glycosylation is highly dependent on other protecting groups.
Stereoselective synthesis of α-glucosides by neighbouring group participation via an intermediate thiophenium ion
Cox, Daniel J.,Fairbanks, Antony J.
experimental part, p. 773 - 780 (2009/09/30)
The use of a 2-O-(thiophen-2-yl)methyl protecting group allows highly stereoselective α-glucosylation of a trichloroacetimidate donor; increased stereoselectivity, presumably arising from the intramolecular formation of a transient intermediate thiophenium ion, correlates with increased bulk of the glycosyl acceptor.
