Thionyl Chloride → Chromone-3-carbonyl chloride

Participants

Reaction Steps

A mixture of chromone-3-carboxylic acid (1.25 g) and thionyl chloride (6 ml) was heated at reflux for 5 minutes. The reaction mixture was then diluted with cyclohexane (15 ml) and ice-cooled. The crystalline precipitate was collected by filtration, washed with cyclohexane and dried under vacuum to give chromone-3-carbonyl chloride (1.2 g). (b) A solution of chromone-3-carbonyl chloride (1.04 g, 5 mmol) in CH2Cl2 (20 ml) was added dropwise over about 5 minutes to an ice-cooled stirred mixture of (endo)-3-aminotropane (0.7 g., 5 mmol), anhydrous K2CO3 (3 g) and CH2Cl2 (20 ml). After addition was complete, stirring was continued for a further 0.5 hour and the mixture diluted With water (50 ml). The organic phase was separated, dried (Na2SO4) and evaporated to give a solid (1.7 g). The base was dissolved in ethanol (15 ml) and acidified with ethanolic HCl to precipitate crude hydrochloride (0.9 g). Recrystallization three times from ethanol gave the title compound as pure hydrochloride (0.3 g), mp. >300° C.

Provenance & Evidence