2-(3-Acylselenoureido)benzonitriles and 2-(3-Acylselenoureido)thiophene-3-carbonitriles. Preparation, Structure Elucidation, Cyclization and Retrocyclization Reactions

Abstract

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Acylselenoureas, selenosemicarbazones and selenocarbamate esters: Versatile ligands in coordination chemistry

“…Subsequently in the 1960's and 1970's, the group of Bulka studied this reaction in some detail and (unsuccessfully) attempted to isolate the acylisoselenocyanates. 5,6 The same procedure was later also used by Koketsu 7 and Pazdera 8 to prepare a variety of new selenourea derivatives. An alternative synthetic method using CH 2 Cl 2 as solvent and polyethylene glycol 400 as a phase-transfer catalyst was reported by Zhang.…”

Synthesis of selenoureas and heterocycles based thereon

“…One of the most efficient and convenient procedure for the synthesis of selenoureas 1 in high yield is based on the reaction of aryl and alkyl isoselenocyanates 2 with various primary and secondary amines [61][62][63][64][65][66][67][68][69][70]. N-Acyl selenoureas 5 can be obtained by reaction of amines with acyl isoselenocyanates 4 which are prepared in turn from acyl chlorides 3 and potassium selenocyanate [68,[71][72][73][74] (Scheme 1). Isoselenocyanates 2 reacted with 3-aminopropanenitrile (6a) to give selenourea 7.…”

“…The first step of this reaction is alkylation of 14 at the selenium atom to give isoselenourea 28 which undergoes cyclization to 4,5-dihydro-1,3-selenazol-4-ol 29, and dehydration of the latter yields 1,3-selenazole 30 (Scheme 8) [92]. Although N,N-disubstituted N′-acylselenoureas 5 were reported previously [68,[71][72][73], they were not involved in the synthesis of 1,3-selenazoles according to the classical Hantzsch reaction until it was modified [92,98].…”