1.4- anhydro triacetate, isomerization

Previously, the reaction of 3,4,6-tri-0-acetyl-l,5-anhydro-2-deoxy-D-arabino-hex-l-enitol (D-glucal triacetate) (20) with lead thiocyanate in a mixture of acetic acid, acetic anhydride, and carbon tetrachloride had been reported by Igarashi and Honma.37 They observed formation of isothiocyanate 21 as the main product, accompanied by a mixture of four isomeric thiocyanates. 

Selective acetylation of l,6-anhydro-j8-D-galactopyranose and its 2-acetate with acetic anhydride in pyridine yielded principally the 2,4-diacetate, which isomerized on passage through a column of silica gel to give a 1 1-mixture of the 2,3- and 2,4-diacetates. ° Selective acetylation of D-galactose using 6.2 molar equivalents of acetic anhydride in the presence of sodium acetate gave the jS-penta-acetate (7.5%), a tetra-acetate fraction (16%), a triacetate fraction (3%), and a diacetate fraction (3%) methylation with diazomethane-boron trifluoride etherate was then used to determine the composition of the various fractions. ... 

---