SIMULTANEOUS FORMATION OF 8H-ISOQUINO[2,1-B][2,7]NAPHTHYRIDIN-8-ONES AND 13H-PYRIDO[4',3' 3,4]PYRROLO[2,1-B][3]BENZAZEPIN-13-ONES, A NOVEL POTENTIAL ALKALOIDAL SYSTEM/

Condensation of 3,4-dihydro-6,7-dimethoxyisoquinoline (4) with 4-methy lnicotinoyl chloride (12) in refluxing pyridine gives imethoxy-8H-isoq uino[2,1-b][2,7]naphthyridin-8-one (11), along with some of its 13,13a -didehydro derivative 7. A similar reaction of 4 with 4-(chloromethyl) nicotinoyl chloride (14) affords, in addition to 7, the isomeric produ ct 8-dimethoxy-13H-pyrido[4',3'b][3]benzazepin-13-one (3). Analogous p airs of products are obtained from 3,4-dihydro-6,7-(methylenedioxy)- a nd 3,4-dihydro-6,7,8-trimethoxy-isoquinolines (15 and 18, resp.). The structure of 3 was established by extensive NMR data and confirmed by single-crystal X-ray studies. Structure 7 has the ring system of the A langium alkaloids like alangimarine (I), while the isomeric ring syste m 3 is predicted to be present in nature on biogenetic reasoning.