Sulfuric Acid → (2R,5S)-7-Methyl-2-[4-methyl-6-[4-(trifluoromethyl)-phenyl]pyrimidin-2-yl]-1,7-diazaspiro[4.4]nonan-6-one sulfuric acid salt

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Reaction Steps

A similarly prepared sample was recrystallised from diethyl ether and isohexane to give the free base form of the title material as a colorless solid with a melting point of 66-67° C. Similarly prepared 7-methyl-2-[4-methyl-6-[4-(trifluoromethyl)-phenyl]pyrimidin-2-yl]-1,7-diazaspiro[4.4]nonan-6-one with a diastereomeric excess of approximately 92% (49 g, 125.51 mmol) in MeCN (700 mL) was suction filtered through a shallow pad of Hyflo to give a clear yellow solution. To this rapidly stirred solution at 50° C. was added 7.5M sulphuric acid (17.6 mL, 132 mmol) over 5 seconds to give a solution which quickly crystallized. The mixture was left to stand at ambient temperature for 2 h then filtered and washed with acetonitrile/Et2O (1:1) (200 ml) then Et2O (150 ml) and dried 50° C. to give the title material (E2) in an 82:1 ratio of (2R,5S) and (2S,5S) isomers (50.6 g) assessed by NMR.

Provenance & Evidence