Studies on fused pyrimidine derivatives. Part 15. Features and mechanistic considerations of the reaction of 5-(alkylaminomethylene)-6-methyleneperhydropyrimidine-2,4-diones with tropone

Abstract

The reaction of 5-(alkylaminomethylene)-6-methyleneperhydropyrimidine-2,4-dione intermediates 3 with tropone 4 gave 2,5-ethanopyrido[2,3-ƒ]quinazolines 5 and/or 6,10a-methanopyrimido[4′,5′:4,5]cyclohepta[1,2-b]azocines 6. The formation of endo- and exo-[4 + 2] cycloadducts and their transformations into these products 5 and 6 will be discussed using the results of PM3 calculations. The X-ray structure of 1-benzyl-7,9-dimethyl-1,2,r-4a,c-5,6,7,8,9,10,c-10b-decahydro-2,5-ethanopyrido[2,3-ƒ]quinazoline-8,10,11-trione and 5-benzyl-1,3-dimethyl-1,2,3,4,r-4b,5,t-6,7,10,11-decahydro-6,10a-methanopyrimido[4′,5′:4,5]cyclopenta[1,2-b]azocine-2,4,10-trione are described.