反应详情

The optically active tetrahydrofuran derivatives are prepared according to Scheme V. Benzyloxyacetaldehyde is reacted with optically active 2-allyl-1,3,2-dioxaborolane-4,5-dicarboxylic acid ester, XVII, to give optically pure (S)-1-phenylmethoxy-4-penten-2-ol, XVIII. Cyclization of alcohol, XVIII, with iodine in the presence of sodium bicarbonate gives a mixture of optically pure 2,5-anhydro-1,3-dideoxy-1-iodo-D-threopentitol, XIX, ##STR112## and 2,5-anhydro-1,3-dideoxy-1-iodo-D-erythro-pentitol, XX, which is separated by flash chromatography using silica gel. ##STR113##