SYNTHETIC ROUTES TO HIGHER-CARBON SUGARS. REACTION OF LACTONES WITH 2-LITHIO-1,3-DITHIANE

Article abstract of DOI:10.1016/S0008-6215(00)85593-7

The per(trimethylsilyl) ether of D-glucono-1,5-lactone reacted with 2-lithio-1,3-dithiane to give, after removal of protecting groups, a 62 percent yield of 1-C-(1,3-dithian-2-yl)-α-D-glucopyranose (3) as a single tautomer; this product is formally a derivative of a 7-carbon, 1,2-dicarbonyl sugar.The crystalline 2,3,4,6-tetraacetate (4) of 3 was readily obtained, again as a single tautomer, and forcing conditions of acetylation led to the acyclic, enol hexaacetate in admixture with the cyclic pentaacetate (6) of 3.Desulfurization of the tetraacetate 4 with Raney nickel gave 1-deoxy-D-gluco-heptulose as its α-pyranose 3,4,5,7-tetraacetate, whereas similar desulfurization of the pentaacetate 6 was accompanied by removal of the tertiary acetoxyl group, providing stereospecific access to the C-β-D-glucosyl compound 2,6-anhydro-1-deoxy-D-glycero-D-gulo-heptitol as its 3,4,5,7-tetraacetate.To explore the effects of chain substituents on the tautomeric behavior of the lacton-derived adducts, the simple lactones 5-pentanolide, 4-butanolide, and 4-pentanolide were made to react with 2-lithio-1,3-dithiane, and the tautomeric compositions of the products wre examined before and after acetylation.This work establishes preparative access to 1,2-dicarbonyl sugars, higher ketoses, and C-glycosyl compounds from readily available lactone precursors.