Studies on Isocarbostyril and Related Compounds. III. Reaction of 2-Methyl-3-aminoisocarbostyril with p-Substituted Benzaldehydes

Study of acylation reactions in 3-aminocarbostyril derivatives

“…In the case of the reaction of 3-(4-methoxyanilino)isocarbostyril (5a) with 4-nitrobenzoyl chloride we successfully isolated one of the main components of the mixture in a pure state, viz. 3-(4-methoxyanilino)-4-(nitrobenzoyl)-1(2H)-isoquinolinone (6). The structure of compound 6 was established on the basis of the data of its 1 H NMR spectrum, in which the signal of the H-4 proton was absent and the signals of N(2)H and 3-NH were retained (Table 1).…”

Condensed isoquinolines. 37.* Heterocyclization using 3-(arylamino)- and 3-(hetarylamino)isoquinolin-1(2H)-ones

“…The fusion of a pyrrole or pyridine ring to face c in these cases has been carried out predominantly by intramolecular acylation or alkylation. In some studies of the properties of 3-amino-2-methyl-and 3-aminoisoquinolin-1(2H)-ones, Ohta [4, 5] and Deady [6] have described the formation of condensed isoquinolines in reactions with aldehydes or ketones. In the present work, we studied the reaction of 3-(arylamino)-and 3-(hetarylamino)isoquinolin-1(2H)-ones with aromatic aldehydes.…”

“…The 1 H NMR spectrum of dibenzo[b,f][1,8]naphthyridine 4a shows three aromatic proton signals from a 1,2,4-trisubstituted benzene ring ( Table 2). The condensation of isocarbostyryl 1a with 4-nitrobenzaldehyde under the same conditions leads to the formation of a mixture of products, of which the major 8]naphthyridine has been observed early in the condensation of 3-amino-2-methylisoquinolin-1(2H)-one with aromatic aldehydes in acetic acid [4,5]. This result is apparently the consequence of intramolecular cyclization of Mannich adduct of the type 6 formed in the reaction of intermediate 3 activated by protonation with a molecule of starting isocarbostyryl 1a.…”