8-Methyl-8-azabicyclo(3.2.1)octan-3-ol → 8-Azabicyclo(3.2.1)octan-3-ol, 8-methyl-, 3-methanesulfonate

Participants

Reaction Conditions

Reaction Steps

Tropine (500 g, 3.54 mol) and triethylamine (590 mL, 430 g, 4.25 mol) were mixed in dichloromethane (10 L) and cooled to <−5° C. under a stream of nitrogen. A solution of methane sulphonyl chloride (329 mL, 487 g, 4.25 mol) in dichloromethane (2 L) was added over 4.33 h between −10.4 and −4.9° C. The mixture was stirred for 15 min, the cooling bath removed, and potassium carbonate solution (2.5 L, GB98596-043)) and deionised water (1.25 L) were added. The additions took 4 min and caused an exotherm raising the temperature to 2.8° C. The mixture was warmed to 15 to 20° C., filtered and the phases allowed to separate. The aqueous phase was extracted further with dichloromethane (2.5 L). The combined organic phases were heated to distil off dichloromethane at atmospheric pressure; 10 L were collected over 1.75 h reaching a base temp. of 42.8° C. and vapour temperature of 42° C. Hexane (7.5 L) was added and after allowing the mixture to cool (overnight) the mixture was filtered and the filtrate returned to a clean flask. The solution was reheated to distil at atmospheric pressure; 7.5 L were collected up to base and vapour temperatures of 60.5 and 62° C. respectively. The mixture was cooled to 0 to 5° C., stirred for 1 h, the product filtered off and washed with hexane (1.5 L). The product was dried under vacuum in a dessicator. Crystallisation from ethyl acetate/hexane or dichloromethane/hexane gave crystalline title compound which was then used in Step 3.

Provenance & Evidence