Diisopropylethylamine → 2-Methyl-2′-(trifluoromethyl)[1,1′-biphenyl]-4-carboxaldehyde

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Reaction Steps

A suspension of 2-methyl-2′-trifluoromethyl-[1,1′-biphenyl]-4-carboxylic acid of Step C (0.50 g, 1.78 mmol) in thionyl chloride (3 mL) was heated at reflux for 90 minutes. After cooling, the thionyl chloride was removed in vacuo and the residue dissolved in toluene. The solution was concentrated in vacuo to yield the crude acid chloride as a brown oil. The acid chloride was dissolved in dichloromethane (5 mL) and slowly added to a solution of 10,11-dihydro-5H-pyrrolo[2,1-c][1,4]benzodiazepine (0.49 g, 2.66 mmol) and N,N-diisopropylethyl amine (0.68 mL, 3.90 mmol) in dichloromethane (15 mL). After stirring for 2 hours, the reaction was quenched with water. The organic layer was sequentially washed with 1 N hydrochloric acid, 1 N sodium hydroxide and brine, dried over anhydrous sodium sulfate, filtered and concentrated in vacuo to give a yellow foam. Purification by flash chromatography using a solvent gradient of 15 to 25% ethyl acetate in hexane gave a white foam which was crystallized by sonication from ethanol/hexane to provide the title compound (0.55 g) as a white solid, m.p. 127-130° C.

Provenance & Evidence