Synthesis of glycosides of 3-deoxy-4-thiopentopyranosid-2-uloses and their reduction products: 3-deoxy-4-thiopentopyranosides
作者:Marı́a Laura Uhrig、Oscar Varela
DOI:10.1016/s0008-6215(02)00292-6
日期:2002.11
Michaeladdition of common thiols to the enone system of (2S)-2-benzyloxy-2H-pyran-3(6H)-one (1) afforded the corresponding 3-deoxy-4-thiopentopyranosid-2-ulose derivatives (2-4). The reaction was highly diastereoselective, and the addition was governed by the quasiaxially disposed 2-benzyloxy substituent of the starting pyranone. As expected from the enantiomeric excess of 1 (ee > 86%) the corresponding
Synthesis of Optically Active 2-Alkoxy-2<i>H</i>-pyran-3(6<i>H</i>)-ones. Their Use as Dienophiles in Diels−Alder Cycloadditions
作者:Christian A. Iriarte Capaccio、Oscar Varela
DOI:10.1021/jo0106896
日期:2001.12.1
cycloadducts 9a-c and 10a were respectively obtained with good diastereofacial selectivity (>80%). Optimized Lewis acid promoted cycloadditions led to 9a-d and 10a,c in higher yields (approximately 80%) and with higher diastereoselectivities (>94%). The major products were formed by approach of the dienes from the less hindered face of the dihydropyranones, and the minor products (such as 11a) were formed