Diisopropylamine → GR 67330

Participants

Reaction Steps

n-Butyllithium (1.45M in hexane; 2.07 ml) was added dropwise to a cold (-70°) stirred solution of diisopropylamine (0.42 ml) in dry THF (20 ml) under nitrogen. The solution was allowed to reach 0° over 30 min, cooled to -70° and added to a cold (-70°) stirred solution of ) 1,2,3,9-tetrahydro-9-methyl-4H-carbazol-4-one (500 mg) in dry THF (10 ml under nitrogen. Hexamethylphosphoramide (0.44 ml) was added and the mixture was allowed to reach 0° over 1 h. The solution was cooled to -70° and a suspension of 4-(chloromethyl)-5-methyl-1-(triphenylmethyl)-1H-imidazole (936 mg) in dry THF (15 ml) was added and the mixture was allowed to reach ca. 20° over 2.5 h. It was stirred for a further 18 h, poured into 8% sodium bicarbonate solution (100 ml) and extracted with dichloromethane (3×50 ml). The combined, dried organic extracts were evaporated to give a semi-solid which was treated with a mixture of acetic acid (10 ml), water (10 ml) and THF (10 ml) and heated at reflux for 1.5 h. The solution was poured into saturated potassium carbonate solution (100 mml) and extracted with dichloromethane (3×50 ml). The combined, dried organic extracts were evaporated to give a solid (ca. 1.8 g) which was purified by SPCC eluting with System A (200:10:1) to give the title compound (17 mg). The 1H-n.m.r. and t.l.c. of this material were consistent with those obtained from the product of Example 8.

Provenance & Evidence