Proton‐ and halogen‐induced cyclizations of 2‐(3‐butenyl)quinazolin‐4(3H)‐ones in the synthesis of pyrrolo[2,1‐b]‐ and pyrrolo[1,2‐а]quinazolinone derivatives

• Published in: Journal of heterocyclic chemistry 2023-03, Vol.60 (3), p.431-448
• Main Authors: Vaskevych, Ruslan I., Savinchuk, Nataliia O., Vaskevych, Alla I., Rusanov, Eduard B., Bylina, Denys V., Kyrylchuk, Andrii A., Vovk, Mykhailo V.
• Format: Article
• Language: English
• ISSN: 0022-152X; 1943-5193
• DOI: 10.1002/jhet.4598

With the aim of finding efficient initiators for electrophilic cyclizations of 2‐(3‐butenyl)quinazolin‐4(3H)‐ones, their reactions with a number of acids (НCl, CF3COOH, H2SO4, polyphosphoric acid, CF3SO2OH) and halogenating agents (I2, Br2, NIS, NBS) have been studied. As established, CF3SO2OH can be successfully applied in the synthesis of linear 1‐methyl‐2,3‐dihydropyrrolo[2,1‐b]quinazolin‐9(1H)‐ones while the use of I2, NIS, or NBS readily leads to angular 1‐(halomethyl)‐2,3‐dihydropyrrolo[1,2‐a]quinazolin‐5(1H)‐ones. The efficient approaches to linear 1‐methyl‐2,3‐dihydropyrrolo[2,1‐]quinazolin‐9(1H)‐ones and angular 1‐(halomethyl)‐2,3‐dihydropyrrolo[1,2‐a]quinazolin‐5(1H)‐ones by proton‐ and halogen‐induced cyclizations of 2‐(3‐butenyl)quinazolin‐4(3H)‐ones have been developed.