Diisopropylamine → HCID 21928739, compound

Participants

Reaction Conditions

Reaction Steps

0.41 cm3 of ethyl diazoacetate is added dropwise to a solution, cooled to −78° C., of 0.8 g of 5-methyl-4,4-diphenylcyclohex-2-enone, which may be obtained according to J. Amer. Chem. Soc. 1995, 107, 5245–61, in 30 cm3 of tetrahydrofuran, followed by slow addition of 11.67 cm3 of lithium diisopropylamide solution prepared from 3 cm3 of 1.6M n-butyllithium and 0.67 cm3 of diisopropylamine in solution in 8 cm3 of tetrahydrofuran. After stirring the reaction mixture at a temperature in the region of −70° C. for 2 hours, 0.34 cm3 of glacial acetic acid is added and the temperature is allowed to rise to the region of 20° C. 100 cm3 of ethyl ether are added and the organic phases are then washed with five times 70 cm3 of distilled water, dried over sodium sulphate and concentrated to dryness under reduced pressure. The residue is dissolved in 25 cm3 of toluene, heated at a temperature in the region of 110° C. for 4 hours and then concentrated to dryness under reduced pressure. The residue obtained is purified by flash chromatography on silica gel (35–70 μm), eluting with a cyclohexane/ethyl acetate (80/20) mixture; 0.133 g of ethyl 7-methyl-6,6-diphenyl-6,7-dihydro-1H-indazole-3-carboxylate is obtained in the form of an off-white solid, the characteristics of which are as follows:

Provenance & Evidence