Morpholine → 2-cyclopropyl-7,8-dimethoxy-2H-chromene-5-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

A solution of 48 ml of morpholine in 50 ml of toluene was added dropwise over 1 hr. under argon to an ice-cold solution of 143 ml of sodium dihydrido-bis-(2-methoxyethoxy) aluminate (3.5M in toluene) diluted with 200 ml of toluene. The resulting reduction solution was then added dropwise under argon during 1 hr. to a solution, cooled to -35° C., of 46 g of methyl (RS)-2-cyclopropyl-7,8-dimethoxy-2H-1-benzopyran-5-carboxylate in 200 ml of toluene and the mixture was stirred at -15° C. for a further 4 hrs. The reaction was stopped by the cautious addition of 40 ml of 3N NaOH and the mixture was left to warm. Extraction: 3×600 ml of ice-water, 1×600 ml of toluene. Chromatography: silica gel, hexane/ethyl acetate 5:1. Crystallization from diethyl ether/ hexane. (RS)-2-Cyclopropyl-7,8-dimethoxy-2H-1-benzopyran-5-carbaldehyde was obtained as a solid.

Provenance & Evidence