Alkoxyallene-Based De Novo Synthesis of Rare Deoxy Sugars: New Routes to L-Cymarose, L-Sarmentose, L-Diginose and L-Oleandrose

Starting from lithiated methoxyallene and lactaldehyde derivatives, the four rare 2,6-dideoxy-hexoses L-cymarose, L-sarmentose, L-diginose and L-oleandrose were synthesized in a stereodivergent fashion. Key steps towards these four target monosaccharides were the oxidative ring openings of allene-derived 2,5-dihydrofurans, diastereoselective carbonyl reductions as well as face-selective hydrogenation protocols. First glycosylation reactions employing thiophenyl glycosyl donors of L-cymarose and L-diginose were performed in high yields and with fair to excellent stereocontrol. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)