Formation of heterocyclic compounds by use of N′-diphenylmethylene-N-phenyl-N-trimethylsilylurea

Abstract

The reactions of N′-diphenylmethylene-N-phenyl-N-trimethylsilylurea (I) with variety of acceptor molecules have been studied. Imidazolidinone, triazinone, and pyrimidinone derivatives were obtained via[4 + 1] or [4 + 2] cyclizations with cyclohexyl isocyanide, methyl isocyanate, dimethyl acetylenedicarboxylate, and trichloroacetonitrile, followed by desilylation with methanol. Dimethylcyanamide reacts with the urea (I) to give 3-diphenyl-methylene-1,1-dimethyl-2-phenylguanidine (VIII)via the thermal decomposition of the intermediate 1,4-dihydro-2-dimethylamino-6-trimethylsilyloxy-1,4,4-triphenyl-1,3,5-triazine. Linear products of insertion into a silicon–nitrogen bond of the urea (I) are obtained, possibly via a common intermediate, in the reactions with diphenylketen and with chloral. 2,3-Dihydro-6-methyl-2,2-diphenyl-3-phenylcarbamoyl-1,3-oxazin-4-one is formed from diketen (4-methyleneoxetan-2-one).