P-Cresol → 4-Methylphenyl 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranoside

Participants

Reaction Conditions

Reaction Steps

8.9 g of p-cresol, 8.9 g of penta-O-acetyl-D-galactopyranose and 0.56 g of ZnCl2 are mixed, heated to 160° C. and kept at this temperature for 30 minutes, according to HELFERICH's method. After cooling to 60° C., the reaction medium is taken up with 400 ml of CH2Cl2 and washed with twice 400 ml of water and then with a solution of sodium hydroxide (≈1N) until the aqueous phase is practically colourless. The organic phase is finally washed with twice 400 ml of water, dried over anhydrous sodium sulfate and then evaporated to dryness in a water bath (temperature: 35°-40° C.) to give a residue of 7.08 g (yield=70%). Chromatography on a column of 60H silica (solvent: hexane/ethyl acetate: 90/10 v/v) gives 2.9 g of the compound 1 (yield=29%) and 1.17 g of its β anomer (yield=12%).

Provenance & Evidence