Synthesis of Thiadiazine, Imidazothiadiazole, Diazospiroundecatetraene and Spirothiadiazolopyrimidinocyclohexadiene Derivatives from 2,5-Dithiobiureas

Abstract

Ethenetetracarbonitrile (2, in tetrahydrofuran solution), diethyl (E)-2,3-dicyanobutenedioate (10, in tetrahydrofuran solution), and 7,7',8,8'-tetracyanoquinodimethane (16, in pyridine solution) act on 1-substituted-2,5-dithiobiureas 1a-c, forming the derivatives of imidazothiadiazole 5a-c, thiadiazine 11a-c and 12a-c, spiro(thiadiazolopyrimidinocyclohexadiene)malononitrile 17a-c and diazospiroundecatetraene 18a-c. Rationales for these conversions involving the nucleophilic addition on diycanomethylene carbon atom are presented.

Chemistry and heterocyclization of dithiobiurea and thioureidoalkylthiourea

“…On the other hand, the addition of THF solution of 1‐substituted‐2,5‐dithiobiureas 4 to a solutions of ethenetetracarbonitrile 58 in the same solvent lead to the formation of 1,2‐bis[5‐(substituted amino)‐1,3,4‐thiadiazole‐2‐yl)hydrazines 62 (Scheme ) [87].…”

“…1‐Substituted hydrazinecarbothioamide 4 reacted with ditheyl ( E )‐2,3‐dicyanobutenedioate 117 in THF at room temperature to give ethyl ( Z )‐2‐[‐2‐amino‐2‐(substituted amino)‐6 H ‐1,3,4‐thiadiazine]‐2‐cyanoacetate 118 and ethyl 5amino‐6‐cyano‐2‐(substituted amino‐6 H ‐1,2,4‐thiadiazine‐6‐carboxylate 119 (Scheme ) [87].…”

“…2‐(Substituted amino)imidazo[2,1‐ b ][1,3,4]thiadi‐azole‐5,6‐dicarbonitriles 128 were formed during the interaction between 1‐substituted‐2,5‐dithiobiureas 4 with ethenetetracarbonitrile 58 (Scheme ) [87].…”

“…The reaction of 1‐substituted‐2,5‐dithiobiureas 4 with 7,7′,8,8′‐tetracyanoquinodimethane 143 in dry pyridine lead to the formation of {5‐amino‐6‐cyano‐2‐(substituted amino)spiro[1,3,4]thiadiazolo[3,2‐ a ]‐pyrimidine‐7,1′‐cyclohexa[2,5]diene‐4′‐ylidene}malononitriles 144 and 1,4‐diamino‐5‐cyano‐9‐(dicyanomethylene)‐ N ‐substituted‐2,3‐diazospiro‐[5,5′]undeca‐1,4,7,10‐tetraene‐9‐thioamides 145 (Scheme ) [87].…”

“…The formation of compounds 144 and 145 can be rationalized by the following mechanism (Scheme ) [87].…”