Derivatives from Isoselenocyanates: Synthesis of 2‐Phenyl‐6 H ‐[5,1,3]benzoselenadiazocine

The reaction of N‐ phenylbenzimidoyl isoselenocyanates 8 with primary and secondary amines in acetone at room temperature, followed by treatment with a base, led to 6 H ‐[5,1,3]benzoselenadiazocine derivatives of type 10 ( Scheme 3 ). An analogous cyclization was observed when 8a and 8b were reacted with the Na salt of diethyl malonate in EtOH at room temperature, which yielded the eight‐membered selenaheterocycles 11 ( Scheme 5 ). The molecular structures of some of the products, as well as that of a sulfur analogue, have been established by X‐ray crystallography ( Figs. 1 – 4 ). The isoselenocyanates 8 have been prepared from N ‐(2‐methylphenyl)benzamides 5 in a three‐step procedure via the corresponding imidoyl chlorides 6 , side‐chain chlorination to give 7 , and treatment with KSeCN ( Scheme 2 ).