4-Methylbenzaldehyde → Lithium Hexamethyldisilazide

Participants

Reaction Conditions

Reaction Steps

A solution of lithium bistrimethylsilylamide was prepared by adding 208 ml of 2.5M n-BuLi to a solution of bistrimethylsilylamine (110 ml, 0.52 mol) in THF (140 ml) at 0° C. After stirring for 15 min, this solution was added via a cannula to a solution of p-tolualdehyde (59 ml, 0.5 mol) in THF (100 ml), while keeping the temperature between -40° and -50° C. The reaction mixture was then allowed to warm up to 10° C. over 30 min. A 2M solution of allyl magnesium chloride (260 ml) in THF was added, keeping the temperature of the reaction between 10° and 15° C. After stirring for 30 min the reaction was poured into a solution prepared by dissolving NH4Cl (150 gm) in H2O (1 liter). The layers were separated and the aqueous layer was extracted with Et2O-hexane. The organic layer was washed with brine, dried over Na2SO4 and evaporated to dryness. The residual oil was added to a solution of (1R)-(-)-10-camphorsulfonic acid (62.5 gm) in EtOAc (1 liter) with cooling. On standing overnight at room temperature, crystals were formed and these were filtered off and washed with EtOAc. The solid was stirred with refluxing EtOAc (300 ml), filtered and washed again with EtOAc. The pure product so formed weighed 60.7 gm (59%). [α]D -27.16 (c=0.5, EtOH).

Provenance & Evidence