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Selenium‐Containing Heterocycles from Isoselenocyanates: Synthesis of 1,2,3‐Selenadiazole Derivatives
Author(s) -
Zhou Yuehui,
Heimgartner Heinz
Publication year - 2000
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(20000315)83:3<539::aid-hlca539>3.0.co;2-6
Subject(s) - chemistry , morpholine , acylation , ethyl diazoacetate , yield (engineering) , diazo , medicinal chemistry , cycloaddition , organic chemistry , cyclopropanation , catalysis , materials science , metallurgy
The reaction of aroyl chlorides 1 with KSeCN and ethyl diazoacetate ( 6 ) in acetone at room temperature yields ethyl 2‐aroyl‐5‐(aroylimino)‐2,5‐dihydro‐1,2,3‐selenadiazole‐4‐carboxylates 7 ( Scheme 3 ). A reaction mechanism via the initial formation of the corresponding aroyl isoselenocyanates 2 followed by a 1,3‐dipolar cycloaddition of the diazo compound with the C=Se bond to give ethyl 5‐(aroylimino)‐4,5‐dihydro‐1,2,3‐selenadiazole‐4‐carboxylates of type D is proposed. Acylation of the latter at N(2) leads to the final products 7 . Deacetylation of 7 to give ethyl 5‐(aroylimino)‐1,2,3‐selenadiazole‐4‐carboxylates 10 is achieved by treatment of 7 with morpholine ( Scheme 5 ). The intermediate isoselenocyanates 2 partially oligomerize to give two different oligomers. The symmetrical one reacts with morpholine to yield selenourea derivatives 12 ( Scheme 6 ).