Collect. Czech. Chem. Commun. 1996, 61, 901-909

An Unequivocal Synthesis of 4-Amino-1,5,6,8-tetrahydropyrido[2,3-d]pyrimidine-2,7-diones and 2-Amino-3,5,6,8-tetrahydropyrido[2,3-d]pyrimidine-4,7-diones

José I. Borrell, Jordi Teixidó, Blanca Martínez-Teipel, Blanca Serra, Josep Lluís Matallana, Marta Costa and Xavier Batllori

Departament de Química Orgànica, CETS Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, E-08017 Barcelona, Spain


An unequivocal set of procedures for the synthesis of 4-amino-1,5,6,8-tetrahydropyrido[2,3-d]pyrimidine-2,7-diones (7) and 2-amino-3,5,6,8-tetrahydropyrido[2,3-d]pyrimidine-4,7-diones (8), in a maximum of four steps from an α,β-unsaturated ester 1, is reported. Thus, the acid hydrolysis of the 2,4-diaminopyrido[2,3-d]pyrimidines 3 yields the 4-amino-2-oxopyrido[2,3-d]pyrimidines 7 while the cyclization of the Michael adducts 9 (formed by reaction of 1 and methyl cyanoacetate) with guanidine affords the corresponding 2-amino-4-oxopyrido[2,3-d]pyrimidines 8. Both isomers were also obtained by hydrolysis of the 4-amino-2-bromo- and 2-amino-4-bromo-5,6-dihydropyrido[2,3-d]pyrimidin-7(8H)-ones 5 and 6, respectively.

Keywords: 4-Oxopyrido[2,3-d]pyrimidines; 2-Oxopyrido[2,3-d]pyrimidines; Dinitrile cyclization; Michael reaction.