Vinylation-electrophilic cyclization of aldopentoses: easy and stereoselective access to C-glycopyranosides of rare sugars

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

“…The methodology utilized in Scheme 5 had been successfully employed for the preparation of C -glycopyranosyl derivatives of common and uncommon sugars like α-gluco, α-manno, β-altro, β-ido, α- and β-gulo, β-talo, α-galacto, and α-allo C -glycopyranosides [ 42 ]. Vinylated derivatives of aldopentoses 11 were treated with Hg(OAc) 2 affording the corresponding cyclized pyanosylmethylmercuric chloride derivatives 12 ( Scheme 5 ).…”

Synthesis of anti-tumour phosphatidylinositol analogues from glucose by the use of ring-closing olefin metathesis

“…This came as a surprise since divinyl zinc has previously given very good selectivity in addition to carbohydrate aldehydes including protected glucose derivatives. 19c, 24 We then turned our attention to the work of Kornienko and d'Alarcao, who have described vinyl Grignard addition to the enantiomer of 9. 25 The reaction is performed in a dichloromethane-THF mixture at −78 °C to afford a 3 : 1 ratio of the two diastereomers.…”

“…R f 0.28 (Et 2 O-CH 2 Cl 2 -hexane, 0.5 : 4.5 : 5); [a] D +4.10 (c 1.1, CHCl 3 ); d H (300 MHz, CDCl 3 ): 7.39-7.19 (m, 22H), 6.86-6.80 (m, 2H), 4.96-4.81 (m, 4H), 4.68-4.48 (m, 6H), 4.02-3.75 (m, 6H), 3.48 (t, J = 9.2 Hz, 1H), 3.40 (dd, J = 9.7, 2.9 Hz, 1H), 2.18 (dt, J = 13.9, 4.4 Hz, 1H), 1. 24…”

A straightforward approach towards glycoamino acids and glycopeptidesviaPd-catalysed allylic alkylation

“…8 For example, Nolan et al reported on the coupling of sugarderived allyl alcohols with protected allyl glycine giving rise to the g,d-unsaturated polyhydroxylated amino acid, 9 which could by cyclized to the C-linked glycosyl amino acid in the presence of Hg-salts (Scheme 1). 10 Best results were obtained with the second generation Grubbs-catalyst (G2) 11 which gave yields around 50%.…”