Nitrogen heterocycles. Part 9. Some reactions of phthalimidin-2-ylacetic acid derivatives, and a new route to lsoindolobenzazepines

Abstract

3-Benzyl-3-hydroxyphthalimidin-2-ylacetic acid (2) can be converted to (E)- and (Z)-3-benzylidenephthalimidin-2-ylacetic acids (3) and (4). These two compounds give (Z)-3-(α-bromobenzylidene)phthalimidin-2-ylacetic acid (9) on bromination. Whilst reaction of bromine with the sodium salt of the (Z)-isomer (8) affords (9), the same reaction with the (E)-isomer (7) leads to 10b-bromo-1-phenyl-4,10b-dihydroisoindolo[1,2-c][1,4]oxazine-3,6(1H)-dione (10), and 9b-(α-bromobenzyl)-3,10b-dihydroisoindolo[1,2-b][1,3]oxazole-2,5-dione (11). Cyclisation of (4) with polyphosphoric acid gives isoindolo[2,3-a][3]benzazepine-5,8(7H)-dione (12). A series of products were obtained from this compound, including both 7,8,13,13a-tetrahydro-5H-isoindolo[2,3-a][3]benzazepine (26) and its methiodide (27), related to Schöpf's base VI.