Diisopropylamine → Lithium diisopropylamide

Participants

Reaction Conditions

Reaction Steps

Lithium diisopropylamide was prepared by adding a solution of n-butyllithium (4 ml, 2.5M in hexane) slowly by syringe into a solution of diisopropylamine (1.01 g) in dry tetrahydrofuran (20 ml) at -65° C. under nitrogen. After stirring at -65° C. for 20 minutes, a solution of methyl 2-phenyl-2-(4,6-dimethoxypyrimidin-2-yl)acetate (2.88 g) in dry tetrahydrofuran (10 ml) was added by syringe. The solution was again stirred for 20 minutes, after which p-toluenesulfonyl cyanide (1.81 g) was added in one portion. The mixture was allowed to warm to room temperature, and was stirred for 3 hours. It was then poured into saturated ammonium chloride solution. The product was extracted with diethyl ether (2×50 ml), dried, evaporated to dryness under vacuum, and flash chromatographed on silica gel, eluting with ethyl acetate/60°-80° petroleum ether (1:4), to give 0.9 g of the desired product as a white solid, mp 91°-93° C.

Provenance & Evidence