Tetrafluoroboric acid →

Participants

Reaction Conditions

Reaction Steps

Methyl magnesium bromide (5.0 mL of a 3.0M solution in ether, 15 mmol) was added dropwise at 0° C. to a solution of 11-[1,1-dimethylethyl]-9-oxo-2,3,6,7-tetrahydro-1H,5H-[1]benzopyrano[6,7,8-ij]quinolizine (2.68 g, 9.03 mmol, prepared in Example 34 above) in dry tetrahydrofuran (10 mL) and the solution was allowed to stand at room temperature for about 17 hours. The reaction mixture was then cooled again to 0° C. and more methyl magnesium bromide (1 mL of a 3M solution in ether, 3 mmol) was added dropwise. The reaction mixture was allowed to attain room temperature and stirred for a further 8 hours, after which time the reaction mixture was poured into tetrafluoroboric acid (44 mL of a 4.4% solution in water) and the resultant mixture was extracted with dichloromethane. The organic phase was separated and dried over sodium sulfate. Removal of solvent, followed by trituration of the residue with ethyl acetate and filtration, gave 11-[1,1-dimethylethyl]-9-methyl-2,3,6,7-tetrahydro-1H,5H-[1]benzopyrano[6,7,8-ij]quinolizinium tetrafluoroborate (1.49 g, 44% yield) as a red solid which melted at 168°-170° C. The structure of this compound was confirmed by mass spectroscopy and by 1H and 13C NMR spectroscopy.

Provenance & Evidence