Synthesis of carbohydrate-derived enynes and subsequent metathesis to yield polyhydroxylated 1-vinylcycloalkenes

In this paper, a new route toward polyhydroxylated 1-vinyl-cycloalkenes is presented. 1,6- and 1,7-enynes were synthesized in four steps from glyco-ynitols, which are readily available from monosaccharides. These compounds were then cyclized by ring-closing enyne metathesis to afford the title compounds. For example, we converted (2R,3S,4R)-1-O-tritylhept-6-yne-1,2,3,4-tetrol (1) to the corresponding 1,7-enyne 13 in 53% yield. The ring-closing metathesis of 1,7-enyne 13 with Grubbs catalyst, under Mori's conditions, produced the corresponding polyhydroxylated 1-vinylcyclohexene 19 in 72% yield. The conversion of several glyco-ynitols into polyhydroxylated 1-vinylcycloalkenes was carried out with satisfying yields. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 159451 Weinheim, Germany, 2003).