Methanol → Tert-butyl 9-oxa-3,7-diazabicyclo[3.3.1]nonane-3-carboxylate hydrochloride

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Reaction Steps

Hydrochloride salt from step (iii) above (146 g, 0.411 mol) and 20% Pd(OH)2-C (7.5 g) were charged to a Parr hydrogenator bottle. Methanol (0.5 L) was added and the bottle was shaken vigorously under an atmosphere of hydrogen at 3.5 bar. The reaction was monitored by GC analysis and was found to be complete after one hour. The catalyst was filtered and the filtrate was concentrated to afford an off-white crystalline product. The crude product was dissolved in hot acetonitrile (1.2 L), and then filtered while hot. The filtrate was diluted with ethyl acetate (1.2 L). The clear solution was allowed to stand overnight at room temperature. The first crop of crystals was collected and dried under vacuum to afford 52 g of sub-title compound as a white solid. The filtrate was concentrated to near dryness, then dissolved in hot acetonitrile (0.4 L), and diluted with ethyl acetate (0.4 L). A second crop of crystals (38 g) was obtained after cooling the solution to 10° C. Both crops were found to be comparable by GC analysis and 1H NMR analyses. Combined yield: 90 g (83%).

Provenance & Evidence