Syntheses of beta-C(1 -> 3)-Glucopyranosides of 2-and 4-deoxy-D-hexoses

The Oshima-Nozaki (Et2AlI) condensation of isolevoglucosenone (4) with 2,6-anhydro-3,4,5,7-tetra-O-benzyl-D-glycero-D-gulo-heptose (5) gave an enone 6 that was converted with high stereoselectivity to 3-C-[(IR)-2,6-anhydro-D-glycero-D-gulo-heptitol-1-C-yl]-2,3-dideoxy-D-ar abino-hexose (1; 1: 1 mixture of alpha- and beta-D-pyranose), and to 3-C-[(1R)-2,6-anhydro-D-glycero-D-gulo-heptitol-1-C-yl]-2,3-dideoxy-D-ly xo-hexose (2; 2.7:1.4:1.0:1.4 mixture of alpha-D-furanose, beta-D-furanose, alpha-D-pyranose, and beta-D-pyranose). The Oshima-Nozaki (Et2AlI) condensation of levoglucosenone (17) with aldehyde 5 gave an enone 18 that was converted with high stereoselectivity to 3-C-[(1R)-2,6-anhydro-D-glycero-D-gulo-heptitol-1-C-yl]-3,4-dideoxy-alph a-D-arabino-hexopyranose (3; single anomer)