Hydrofluoric Acid → 8-chloro-6,11-dihydro-11-(1-methyl-piperidylidene)-5H-benzo[5,6]cyclohepta[1,2-b]pyridine

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Reaction Steps

To a solution of a product of Step D above (59 g, 0.15 mole) in 120 mL (120 g, 6.0 mole) of hydrofluoric acid at -35° C. is added boron trifluoridine (44.3 g, 0.66 mole) over 1 hour. Completeness of the reaction is determined by thin-layer chromatography. The reaction is quenched using ice, water and potassium hydroxide to a final pH of 10. The product is extracted into toulene and the toluene solution is washed with water and brine. The toluene solution is concentrated to a residue, which is dissolved in hot hexane. Insolubles are removed by filtration and the filtrate is concentrated to an off-white powder. Yield: 45.7 g (HPLC purity 96%), 92% of theory.

Provenance & Evidence