Chlorotrimethylsilane → Lithium diisopropylamide

Participants

Reaction Conditions

Reaction Steps

Lithium diisopropylamide was prepared by the addition of 2.1 M n-butyllithium in hexane (22.7 ml, 48.8 mM) to diisopropylamine (3.45 ml, 48.8 mM) in dry tetrahydrofuran (125 ml). The base is cooled to -70° C., 1-benzyloxy-2,6-dimethyl-10-oxo-undec-6-ene (12.4 g, 41 mM) in dry tetrahydrofuran (300 ml) is added and the mixture is allowed to stir for 1 hour. Trimethylsilyl chloride (14 ml, 111 mM) is added to triethylamine (3.7 ml, 26.8 mM) in dry tetrahydrofuran (50 ml). The mixture is centrifuged, and the supernatant is added to the lithio salt at -70° C. After 4 hours, sodium bicarbonate (2.5 g) and saturated sodium bicarbonate (250 ml) are added, the reaction mixture is partitioned between ether and brine, the aqueous phase is extracted with ether and the combined extracts are washed with brine and dried (Na2SO4). The solvent is removed in vacuo to give crude 11-benzyloxy-6,10-dimethyl-2-trimethylsiloxy-undec-1,5-diene.

Provenance & Evidence