6//-Pyrido quinazoline-6-thione

Treatment of pyrimidine-2-thione 193 with AICI3 in PhN02 yielded 2-(4-benzylphenyl)-6-oxo-6,7-dihydro-4//-pyrido[6,l-a]isoquinolin-4-thione (194) (98MI47). Cyclization of l-(2-carboxyethyl)-l,2,3,4-tetrahydroquina-zoline-2,4-dione (195) in PPA afforded l,2,3,5,6,7-hexahydropyrimido[3,2, l-//]quinazoline-l,3,7-trione (196) (97CHE96). 

Treatment of resin-bound iminophosphorane 197 with an excess of solid CO2 and CS2 in a sealed glass tube, and with aryl isocyanates afforded I-OXO-, 1-thioxo- 198, and l-arylimino-l//-pyrido[l,2-c]pyrimidine-3-car-boxylates 199 (OlJMClOll). Reaction of iminophosphorane 200, derived from 2-(2-azidophenyl)pyridine with excess PPh3, yielded 6//-pyrido[l,2-c] quinazoline-6-thione (201). 

Allylation of the pyrido[l,2-a]quinazoline-l,5-dione 136 (R = Ph, Ar = Ph) with allyl bromide afforded the corresponding 3-allyloxy derivatives. The hydroxymethylene group of the azepino[l,2-a]quinazolinone 142 was acetylated with acetyl chloride. When the cyclopenta[e]pyrido[l,2-a]py-rimidine-4-thione 160 (n = 0) was treated with methyl io de, a quaternary salt (177) was obtained. ... 

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