Saturated heterocycles. 254. Synthesis and stereochemistry of saturated or partially saturated pyridazino-[6,1-b]- and phthalazino[1,2-b]quinazolinones

摘要

By the reaction of anthranilic hydrazide 1 with cis-2-(P-methylbenzoyl)-1-cyclohexanecarboxylic acid 2a or diendo-3-(p-methylbenzoyl)bicyclo[2.2.1]heptane-2-carboxylic acid 2b, fused tetra-and pentacyclic ring systems 3a,b were prepared. trans-2-Amino-1-cyclohexanecarbohydrazide 4b was reacted with 3-(p-chlorobenzoyl)propionic acid 5 to yield the pyridazino[6, 1-b]quinazolinone 6. From the reaction of cis-2-amino-1-cyclohexanecarbohydrazide 4a with 2a, three isomeric partially saturated 8H-phthalazino[1,2-b]quinazolin-8-ones 7a-c were formed, The reaction of diexo-2-aminobicyclo[2.2.1]heptane-3-carbohydrazide 4c and 2a furnished the pentacyclic derivatives 8 and 9 containing a 3-aryl-4,5-dihydropyridazine or 3-aryl-hexahydropyridazine ring C with cis annelated C/D rings. The formation of 8 and 9 involving different ring systems can be rationalized by two reaction pathways: (i) in the bislactam 9 the carboxyl group acylates the hydrazide, while (ii) in 8 it forms a pyridazine ring with the cyclic amino group by cyclocondensation. The structures of the products were elucidated by H-1 and C-13 nmr methods, including DEPT, DNOE and 2D-HSC measurements. [References: 40]