Diisopropylamine → 1,1,4,4,7-Pentamethyl-6-ethynyl-1,2,3,4-tetrahydronaphthalene

Participants

Reaction Conditions

Reaction Steps

n-Butyllithium was added to a solution of freshly distilled diisopropylamine (3.01 mL, 21.5 mmol) and THF (41 mL) at 0° C. under argon. After 10 min, the solution was cooled to -78° C. and a solution of methyl (5,6,7,8-tetrahydro-3,5,5,8,8-pentamethylnaphthalen-2-yl) ketone (Compound 16) and THF was added dropwise. The solution was stirred for 1 h at -78° C. and then diethyl chlorophosphate (3.27 mL, 22.6 mmol) was added. The dry-ice bath was removed, and the solution was allowed to warm to room temperature over 1 hour and added dropwise to a -78° C. solution of lithium diisopropylamide (43.1 mmol) and THF (82 mL) prepared as described above. The resultant mixture was warmed to room temperature over 3 hours and quenched with water. The products were extracted with hexanes, washed with 1N HCl, water, brine, dried (MgSO4) and concentrated under reduced pressure. The residue was purified by flash chromatography (SiO2, hexanes) to give the title compound as a colorless solid (4.3 g, 93%).

Provenance & Evidence