Acetic Acid → 3,7-Dibenzyl-3,7-diazabicyclo[3.3.1]nonan-9-one

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Reaction Steps

In a minor modification of the previous procedure, a solution of 1-benzyl-4-piperidone (4.73 g, 25.0 mmol) and glacial acetic acid (1.50 g, 25.0 mmol) in methanol (25 mL) was added as before to a boiling mixture of paraformaldehyde (6.00 g, 200 mmol), glacial acetic acid (1.62 g, 27.0 mmol), benzylamine (2.68 g, 25.0 mmol), and methanol (100 mL). The reaction time was 24 hours and the aqueous workup was as described previously. Instead of the distillation described, the crude oil from the workup was then digested in Skelly B (300 mL) on a steam bath for 0.5 hours. The hot supernatant was decanted from the yellow residue and evaporated (aspirator followed by vacuum pump, room temperature 0.02 mm Hg, 20 min). This afforded N,N'-dibenzyl-3,7-diazabicyclo[3.3.1]nonan-9-one (6.84 g, 85.4%) as a white oil that did not solidify after 3 days at -10° C. The 1H and 13C NMR spectra of this oil were virtually identical to that described for the ketone produced in Example XXIII via method A and the material proved to be satisfactory for use in the following Examples XXV and XXVI. ##STR40##

Provenance & Evidence