Syntheses of β ‐C(1→3)‐Glucopyranosides of 2‐ and 4‐Deoxy‐ D ‐hexoses

The OshimaNozaki (Et 2 AlI) 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 ‐[(1 R )‐2,6‐anhydro‐ D ‐ glycero‐ D ‐ gulo ‐heptitol‐1‐ C ‐yl]‐2,3‐dideoxy‐ D ‐ arabino ‐hexose ( 1 ; 1 : 1 mixture of α ‐ and β ‐ D ‐pyranose), and to 3‐ C ‐[(1 R )‐2,6‐anhydro‐ D ‐ glycero‐ D ‐ gulo ‐heptitol‐1‐ C ‐yl]‐2,3‐dideoxy‐ D ‐ lyxo ‐hexose ( 2 ; 2.7 : 1.4 : 1.0 : 1.4 mixture of α ‐ D ‐furanose, β ‐ D ‐furanose, α ‐ D ‐pyranose, and β ‐ D ‐pyranose). The OshimaNozaki (Et 2 AlI) condensation of levoglucosenone ( 17 ) with aldehyde 5 gave an enone 18 that was converted with high stereoselectivity to 3‐ C ‐[(1 R )‐2,6‐anhydro‐ D ‐ glycero‐ D ‐ gulo ‐heptitol‐1‐ C ‐yl]‐3,4‐dideoxy‐ α ‐ D ‐ arabino ‐hexopyranose ( 3 ; single anomer).