Synthesis of spiro(benzo[h]quinazoline-5,1′-cyclohexane) derivatives

Abstract

3-p-Methoxyphenyl-4-oxo-2-mercapto-3, 4, 5, 6-tetrahydrospiro(benzo[h]quinazoline-4,1 ′-cyclohexane) wassynthesized by the reaction of 4-amino-3-ethoxycarbonvl-1, 2-dihydrospiro(naphthalene-2,1 '-cyclohexane) (1) with p-methoxyphenvl isothiocyanate without separation of the thioureido derivative. Amino ester 1 is transformed byacetamide and formamideinto 2-methyl-4-oxo-3, 4, 5, 6-tetrahydrospiro(benzo[h]quinazoline-5,1 ′-cyclohexane) and 4-oxo-3, 4, 5, 6-tetrahydrospiro(benzo[h]quinazoline-5,1′-cyclohexane (11), respectively. Alkylation of quinazoline 11 with methyl iodide results in formation of 3-methyl-4-oxo-3, 4, 5, 6-tetrahydro-spiro (benzo[h]quinazoline-5,1 ′-cyclohexane). Amino ester 1 reacts with caprolactam with formation of 2, 3 pentamethylene-4-oxo-3, 4, 5, 6-tetrahydrospiro(benzo[h]quinazoline-5,1′-cyclohexane). 4-Ethoxymethyleneamino-3-ethoxy-carbonyl-1,2-dihydrospiro(naphthalene-2,1′-cyclohexane) was synthesized by the reaction of amino ester 1 with o-formic ester, and was converted into 3-amino-4-oxo-3, 4,5, 6-tetrahydro-spiro(benzo[h]quinazoline-5,1′-cyclohexane) (VIII) by hydrazine hydrate. Aminoquinazoline VIII is acylated by acid chlorides with formation of 3-acylamino-4-oxo-3,4,5,6-tetrahydrospiro(benzo[h]quinazoline-5,1′-cyclohexanes) and forms 3-benzyl-ideneamino-4-oxo-3,4,5,6-teirahydrospiro(benzo[h]quinazoline-5,1′-cyclohexane) with benzaldehyde.