Treatment of the sulfinamide anhydride (2), prepared from anthranilic acid (1), with 3, 4-dihydro-6, 7-dimethoxyisocarbostyril (9) gave 5, 6, 7, 8-tetrahydro-2, 3-dimethoxy-8-oxoisoquinolo [1, 2-b] quinazoline (10), which was also obtained by heating isatoic anhydride (3) with 9. Similarly, rutecarpine (6) was synthesised by the reactions of 1, 2, 3, 4-tetrahydro-1-keto-β-carboline (13) with the sulfinamide anhydride (2) or isatoic anhydride (3). Heating 3, 4-dihydro-β-carboline (5) with 3 also afforded rutecarpine (6). Furthermore the phosphates (8a) and (12) were isolated on treatment of the urethanes (7a) and (11) with phosphoryl chloride.