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1-(2-Bromo-α-methyl-4,5-methylenedioxybenzyl)-1,2,3,4-tetrahydro-6,7-dimethoxyisoquinoline (7a) and its analogues (26a) and (26b) were prepared by well known routes. When they were treated with formaldehyde and hydrochloric acid the expected Mannich reaction to give the 12-bromo-13-methyltetrahydroprotoberberines did not take place. A novel rearrangement occurred to give the unexpected isoquinobenzoxazepines (16a), (27a), and (27b), respectively, the structures of which were assigned by i.r., u.v., n.m.r., and mass spectroscopy and confirmed by comparison of some of their degradation products with compounds synthesised by standard methods. Unequivocal evidence for the structure and stereochemistry of these compounds were obtained by an X-ray crystallographic study on compound (27a). Some aspects of the scope and mechanism of this novel reaction have been explored.

Two new routes for the synthesis of dihydrojasmone (10a) and cis-jasmone (10b)via 1,4-diketones (5a and b) are described. For the first route, pent-4-en-1-ol (1) was oxidised to the corresponding aldehyde (2), which on reaction with suitable Grignard reagents gave the olefinic alcohols (3a and b). The former (3a) was oxidised directly to the diketone (5a) by Jones reagent catalysed by Hg-(OAc)2. The latter (3b) was oxidised stepwise, first by PCC to give (4), then by PdCl2 to yield (5b). For the second route, pent-4-yn-1-ol (6) was converted to the aldehyde (7), which on Grignard reaction using suitable reagents gave the hydroxy-acetylenes (8a and b). These were oxidised to the corresponding acetylenic ketones (9a and b), which in turn were converted by Hg2+ catalysed hydration to (5a and b). Base cyclisation of the diketones (5a and b) yielded (10a and b) respectively.