Pyrimidinones pyrano

The products could be easily isolated by filtration, and recrystallizafion from elhanol led to the pure desired compounds. The authors suggested an iminium ion-catalyzed Knoevenagel condensation mechanism, followed by enamine-Michael addition and intramolecular cyclization. One year later, the same group reported the diammonium hydrogenphosphate-catalyzed synthesis of various pyrano-pyrimidinones by exchanging dimedone by barbituric and thiobarbituric add in aqueous ethanol at ambient temperature [13]. The desired compounds could be afforded in good yields. 

Reactions of barbituric and N,N-dimethylbarbituric acids 191 with UNs 30 and 33 open access to pyrano[2,3-d]pyrimidinones 192 (73CB914, 84JOU2236, 03TL8307, 05CAL39) (Scheme 71). 

A series of pyrano[2,3-d]pyrimidinones 18 were synthesized from three-component one-pot reactions between aromatic aldehydes, malononitrile, and barbituric acids (17) in water in the presence or absence of catalysts (Scheme 9) [86,89,93],... 

SCHEME 27 DAHP-catalyzed synthesis of substituted pyrano[2,3-d]pyrimidinone derivatives 18 in ethanol-water media [132]. DAHP, diammonium hydrogen phosphate. 

A. Mobinikhaledi, M.A.B. Fard, Tetrabutylammonium bromide in water as a green media for the synthesis of pyrano[2,3-d]pyrimidinone and tetrahydrobenzo[6]pyran derivatives, Acta Chim. Slov. 57 (2010) 931-935. 

A. Mobinikhaledi, N. Foroughifar, M.A.B. Fard, Eco-friendly and efficient synthesis of pyrano[2,3-d] pyrimidinone and tetrahydrobenzo[i ] pyran derivatives in water, Synth. React. Inorg. Met.-Org. Nano-metal Chem. 40 (2010) 179-185. 

S. Balalaie, S. Abdolmohammadi, H. RezaBijanzadeh, A. Mohammad Amani, Diammonium hydrogen phosphate as a versatile and efficient catalyst for the one-pot synthesis of pyrano[2,3-d]pyrimidinone derivatives in aqueous media, MoL Divers. 12 (2008) 85-91. 

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