Divergent and Regioselective Synthesis of (Trifluoromethyl/carboxyethyl)benzo[4, 5]imidazo[1, 2‐a]pyrimidines from β‐Enamino Diketones. Issue 41 (20th October 2020)

• Record Type: Journal Article
• Authors: Andrade, Valquiria P.; Mittersteiner, Mateus; Bonacorso, Helio G.; Martins, Marcos A. P.; Zanatta, Nilo
• Is Part Of: European journal of organic chemistry. Issue 41(2020)
• Page Start: 6478
• Page End: 6484
• Publication Date: 2020-10-20
• Subjects: Imidazopyrimidines -- Triflouromethyl -- 1, 3‐Diketones -- Acylated enaminones -- β‐Enaminodiketones; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202001142
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : A divergent and regioselective cyclocondensation reaction of β‐enamino diketones with 2‐aminobenzimidazole is reported. The β‐enamino diketones react with 2‐aminobenzimidazole to form exclusively 1, 2‐ or 1, 4‐regioisomers of benzo[4, 5]imidazo[1, 2‐ a ]pyrimidines, depending on the nature of the EWG group in the diketones: when the diketone has a carboxyethyl group, only the 1, 2‐regioisomer was obtained; and when the EWG = CF3, only the 1, 4‐regioisomer was isolated. The structure of the obtained products was unambiguously determined by 2D‐NMR experiments and single‐crystal X‐ray analysis. Abstract : β‐Enamino diketones were cyclocondensed with 2‐aminobenzimidazole to selectively furnish 1, 2‐ or 1, 4‐regioisomers of benzo[4, 5]imidazo[1, 2‐ a ]pyrimidines. The selectivity of the reaction was found to be mainly due to the nature of the group (trifluoromethyl or carboxyethyl) attached to the ketone moiety.