Reaction of 1‐acylthiosemicarbazides with ethenetetracarbonitrile

Abstract

1‐Acylthiosemicarbazides 9a‐d reacted with ethenetetracarbonitrile (TCNE, 2) in ethyl acetate with formation of N′‐(4‐amino‐5,6‐dicyano‐2H‐1,3‐thiazin‐2‐ylidene) substituted hydrazide 10a‐d, N′‐(5‐amino‐3,4‐dicyano‐2H‐pyrrol‐2‐ylidene)‐2‐substituted hydrazide 11a‐d and 2‐substituted imidazo[2,1‐b][1,3,4]‐oxadiazole‐5,6‐dicarbonitrile 12a‐d. Rationales for the conversions observed are presented.

1,4‐Dioxo‐1,4‐dihydronaphthalene‐2,3‐dicarbonitrile and 1,1,2,2‐Tetracyanoethene in Heterocyclization

“…Concentration of the preparative runs resulted in formation of colorless precipitates of oxadiazole derivatives 91a , 91b , 91c , 91d (28–39%, Scheme ). Whilst the solution of the filtrate contained thiadiazoles 92a , 92b , 92c , 92d in (38–47%, Scheme ) .…”

Heterocyclization of acylthiosemicarbazides

“…N ′‐2‐ (5‐Amino‐3,4‐dicyano‐2 H ‐pyrrol‐2‐ylidene)‐2‐substituted hydrazide 17 was obtained via interaction between 1‐acylthiosemicarbazides 2 with ethenetetracarbonitrile (TCNE, 16 ) in ethyl acetate [77]. …”

“…1‐Acylthiosemicarbazides 2 reacted with TCNE ( 16 ) in ethyl acetate to give N′‐(4‐amino‐5,6‐dicyano‐2H‐1,3‐thiazin‐2‐ylidene) substituted hydrazides 94 [77].…”

“…1‐Acylthiosemicarbazides 2 is reacted with TCNE ( 16 ) in ethyl acetate to give 2‐subsituted imidazo[2,1‐ b ]oxadiazole‐5,6‐dicarbonitrile 113 [77].…”

Novel Synthesis of 1,3‐Thiazine and Pyrimidinethione Derivatives from (1‐Aryl ethylidene)hydrazinecarbothioamides and Tetracyanoethylene

“…Also, it can act as an umpolung source of dicyanomethylene . The addition of nucleophiles to the double bond of TCNE, subsequently loss cyanide afforded tricyanovinylation intermediates , which is the common reaction. On the other hand, direct addition to one of the nitrile groups can also occur but is less frequent .…”