The acetonation of methyl 5-C-methoxy-β-d-galactopyranoside1The nomenclature for these bis-glycosides is still somewhat ambiguous, since the introduction of a substituent at C-5, according to the Cahn, Ingold, Prelog rules, may invert its absolute configuration. We have preferred to use the Fischer nomenclature, since it is simpler and directly correlated with the name of the base compound, which undergoes a substitution of a hydrogen atom with a MeO group. This nomenclature has been previously used by us and by other authors, and is reported without change in Chemical Abstract. According to the more recent rules, the name would be methyl (5R)-5-methoxy-α-l-arabino-hexopyranoside.1 with 2,2-dimethoxypropane
作者:Maria Camilla Bergonzi、Giorgio Catelani、Felicia D’Andrea、Francesco De Rensis
DOI:10.1016/s0008-6215(98)00211-0
日期:1998.10
Abstract The acetonation of methyl 5- C -methoxy- β - d -galactopyranoside ( 1a ), masked bis-glycoside form of l - arabino -hexos-5-ulose, with a large excess of 2,2-dimethoxypropane and catalytic amounts of p -toluenesulfonic acid gives a mixture of five acetonides. The most abundant isolated product was the mixed acetal methyl 6- O -(1–methoxy-1-methylethyl)-3,4- O -isopropylidene-5- C -methoxy-