Selenium-containing heterocycles from isoselenocyanates: 4-methylselenazole derivatives from the reaction with malononitrile and propargyl chloride

Aryl isoselenocyanates 1 react with malononitrile (6a) and propargyl chloride (8) in DMF in the presence of Et3N to give the corresponding 2-(3-aryl-2,3-dihydro-4-methyl-1,3-selenazol-2-ylidene)malononitriles 12 as major products. The analogous reaction takes place with benzoylacetonitrile (6f) instead of 6a. In some cases, the corresponding noncyclic 2-[(arylamino)(prop-2-ynylselanyl)methylidene]malononitriles 9 were obtained as minor products. The structures of 9e and 11a have been established by X-ray crystallography.