A number of variously substituted α- and β-nitrothiophenes undergoes ring opening by treatment with secondary amines in mild conditions. Anyway, at variance with 3,4-dinitrothiophene, all of the other derivatives break just one C-S bond, leading to asymmetrically functionalized nitrobutadienes which can be isolated in good yields after alkylation at sulfur. Such appealing building-blocks have been successfully employed in a number of synthetic procedures mainly targeted to the preparation of heterocycles of various nature (nitrogen, oxygen or sulfur heterocycles) within an overall ring-opening/ring-closing protocol. Furthermore, some of the nitrobutadienes produced by the ring-opening have revealed, after proper modification of the existing functionalities, interesting pharmacological activities.
Versatile nitrobutadienic building-blocks from the ring opening of 2- and 3-nitrothiophenes
BIANCHI, LARA;MACCAGNO, MASSIMO;PETRILLO, GIOVANNI;SANCASSAN, FERNANDO;TAVANI, CINZIA;
2007-01-01
Abstract
A number of variously substituted α- and β-nitrothiophenes undergoes ring opening by treatment with secondary amines in mild conditions. Anyway, at variance with 3,4-dinitrothiophene, all of the other derivatives break just one C-S bond, leading to asymmetrically functionalized nitrobutadienes which can be isolated in good yields after alkylation at sulfur. Such appealing building-blocks have been successfully employed in a number of synthetic procedures mainly targeted to the preparation of heterocycles of various nature (nitrogen, oxygen or sulfur heterocycles) within an overall ring-opening/ring-closing protocol. Furthermore, some of the nitrobutadienes produced by the ring-opening have revealed, after proper modification of the existing functionalities, interesting pharmacological activities.
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