A facile permethylation of cord factor

Small quantities of cord factor (trehalose-6,6'-dimycolates) can be readily and almost quantitatively permethylated in anhydrous diethyl ether/dimethylformamide mixtures with CH3I and NaH-oil dispersion in the presence of molecular sieve. Hydrolysis of the permethylated products from cord factor "Peurois" and 'P3-Aoyama-b' prove these to be 6,6'-dimycolates. Experiments with a 4-palmitoyl glucose suggest that acyl migration in this system may not occur.