α-Oxytosylation of Ketones: Synthesis of Thiazoles and Imidazoles

Significance

A previous study on the use of N-alkyl-O-acyl reagents in the α-oxyacylation of carbonyl compounds (N. C. O. Tomkinson and co-workers Org. Lett. 2005, 7, 5729) appears to have prompted the discovery of an analogous reagent for the transfer of an oxysulfonyl group which is ­reported here. The reagent, N-methyl-O-tosyl­hydroxylamine (A), was used to effect α-tosylation of various aliphatic and aromatic, symmetrical and unsymmetrical ketones. The yields of the tosylation range from moderate to good. The value of the methodology was shown in the one-pot synthesis of thiazoles and imidazoles in good overall yields. The substrate scope in the tosylation was well studied but only four heterocycles were synthesized.