Azepino quinazolinones

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. ... 

Suschitzky and co-workers hydrogenated the lactam 305 over palladium on charcoal under pressure in the presence of 1 molar equivalent of hydrochloric acid in ethanol at room temperature and observed the formation of the azepino[2, l- )]quinazolinone 306 and its iV-oxide 307 in yields of 12 and 69%, respectively. 

The azepino[2,l-i>]quinazolinone iV-oxide 307 was deoxygenated to the azepino[2,l-A]quinazolinone 306 upon irradiation of its methanolic solution for 96 hr. ... 

Reduction of the azepino[2, l- )]quinazolinone 348 with sodium borohy-dride in methanol led to the ring-opened product 349 at ambient temperature and to the azepino[2,l- >]quinazolinone 350 at — 20°C. ... 

Horvath et reported that the tricyclic formyl derivatives 390 n = 0-2) exhibit triple tautomerism between forms 451 and 453. The imine-enamine-enol tautomerism depends greatly on the ring size ( ). A significant solvent dependence was observed only for the pyirolo[2,l-i ]-quinazolinones 390 n = 0), which in ethanolic solution exist predominantly in the imino form (451), and in chloroform in the enol form (453). H-NMR spectroscopy showed that in chloroform the proportion of the imine tautomer 451 was about 5%. The fast equilibrium between the en-amine and enol forms 452 and 453 was shifted considerably toward the enamine tautomer 452 in the case of the pyrido[2,l-fi]quinazolinones 390 ( = 1). The azepino[2,1 -6]quinazoline ( = 2, R = 2-NO2) is a 2 3 mixture of the imine and the enamine tautomers 451 and 452. 

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