Synthesis of thromboxane A2 models from glucose

Trans-opening of the 2,3-anhydro-6-deoxy-4-O-methyl-α-d-allopyranoside with lithium bromide yields the altro and gluco regioisomers methyl 2-bromo-2,6-dideoxy-4-O-methyl-α-d-altropyranoside and methyl 2-bromo-3,6-dideoxy-4-O-methyl-α-d-glycopyranoside which can be hydrolysed to give the sugar precursors 2-bromo-2,6-dideoxy-4-O-methyl-α/β-d-altropyranose and 3-bromo-3,6-dideoxy-4-O-methyl-d-glucopyranose. Under Mitsunobu conditions the altro compound yields the first 1,3-anhydro-altrose derivative. In case of the gluco derivative alkaline treatment does not give a 1,3-anhydro-glucose derivative but the 2,6-dideoxy-altrose via intermediate 2,3-epoxide formation. Methanolysis and reductive debromination under photolytic initiation were studied.