A facile and regioselective synthesis of donor-substituted 2-(2-halophenyl)acetaldehyde acetals

Article abstract of DOI:10.1002/ardp.19953280402

Starting from vanillin (5a) a facile and high yielding procedure for the preparation of the donor substituted (2-bromophenyl)- and (2-iodophenyl)-acetaldehyde acetals 13c and 16c is described. Homologization of O-benzylvanillin to obtain the phenylacetaldehyde acetal 15c succeeds by Wittig reaction with the phosphonium chloride 11 and subsequent addition of methanol. 15c is brominated with pyridinium bromide perbromide in methanol to yield the bromo acetal 13c in 65% yield from vanillin. Iodination of 15c with iodine and iodic acid leads to the iodo acetal 16c.