DIHETEROARYLMETHANES .2. ACTIVE METHYLENE BEHAVIOR OF 2-THIAZOLYL AND2-OXAZOLYL DERIVATIVES

The methylene group of bis(2-benzothiazolyl)methane (bbtmH), 1, bis(2- benzoxazolyl)methane (bbomH), 2, and bis[2(5-ethoxycarbonyl-4-methyl)t hiazolyl]methane, 3, undergoes azo-coupling with benzenediazonium chlo ride to the corresponding phenylhydrazono derivatives, nitrosation wit h nitrous acid to the corresponding oximes, and crotonic-type condensa tion with alkyl, aryl, and heteroaryl aldehydes. In the condensation o f bbomH, 2, with salicylaldehyde, one of the benzoxazole moieties unde rgoes ring opening and the final product is a coumarin derivative. The methylene group of 1 and 3 is also sensitive to oxidation by air in a lkaline solution leading to the corresponding carbonyl compounds 15 an d 17. The analogous reaction carried out on bbomH was found to be slug gish. The behaviour of these diheteroarylmethanes thus conforms with t he one typically exhibited by ''active'' methylene compounds, substitu ted by efficient electron-withdrawing groups.