Water → 3-Benzyl-9-oxa-3,7-diazabicyclo[3.3.1]nonane

Participants

Reaction Conditions

Reaction Steps

Water (11.2 mL) and concentrated sulfuric acid (24.5 mL) were added to 5-benzyl-3,7-dihydroxy-1-phenylsulfonyl-1,5-diazacyclooctane (2.92 g, 7.76 mmol; see step (ii) above). The reaction mixture was heated for 24 hours at 95° C. The temperature was adjusted to 60° C., and toluene (40 mL) was added. Sodium hydroxide solution was then added (150 mL of 5 M), causing the internal temperature to rise to 85° C. The pH of the reaction mixture was then checked, and was found to be 2. A few pellets of solid sodium hydroxide were then added. The pH was measured again, and was found to be 13. The layers were separated, and the aqueous phase extracted with toluene (50 mL). The organic phases were combined, dried (MgSO4), filtered and concentrated in vacuo to provide 3-benzyl-9-oxa-3,7-diazabicyclo[3.3.1]nonane as an orange-brown oil. This can be converted to the title compound (dihydrochloride salt) by reaction with hydrochloric acid under standard conditions.

Provenance & Evidence