N-[2-(2,3-dihydro-1H-indol-1-yl)phenyl]-4-methyl-1-piperazinecarboxamide → 6-(4-Methyl-1-piperazinyl)-1,2-dihydrobenzo[b]pyrrolo[3,2,1-jk][1,4]benzodiazepine

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Reaction Steps

To 21.1 g (0.0627 mole) of N-[2-(2,3-dihydro-1H-indol-1-yl)phenyl]-4-methyl-1-piperazinecarboxamide of Example 7a was added 500 ml of phosphorus oxychloride and this was refluxed under nitrogen overnight. The excess POCl3 was then removed at aspirator pressure with warming. The residue was boiled and triturated on the steam bath with 60 ml of absolute ethanol until solution resulted. This solution was cooled and stirred resulting in separation of a solid. This solid was collected, washed with ethanol, with ether, and finally hexane, then dried to afford 19.0 g. This was partitioned between 200 ml of chloroform and 100 ml of water, with good stirring. Addition of 2.5N-NaOH rendered the medium basic, and the product base passed into the organic phase. This was separated, washed twice with water, dried over Na2SO4 and concentrated to 6.5 g of an oil. This oil was boiled with 60 ml of acetone, filtered from some insolubles, and the filtrate concentrated under nitrogen to 20 ml and allowed to crystallize. This gave 2.6 g of solid, m.p. 144°-146° C. dec. This material was treated with 20 ml of 2N-HCl with stirring. The resulting solution was filtered from a small amount of insolubles, then made basic with 2.5N-NaOH and the product extracted into dichloromethane. The latter extract was washed twice with water, dried over Na2SO4, and concentrated to an oil which began to crystallize. This was quickly dissolved in a small volume of boiling acetone and allowed to crystallize. The crystals were collected, washed with a little acetone, and dried to afford 2.00 g (10% overall yield) of 6-(4-methyl-1-piperazinyl)-1,2-dihydrobenzo[b]pyrrolo[3,2,1-jk][1,4]benzodiazepine, m.p. 149°-151° C.

Provenance & Evidence