(RS)-3-(1-cyclopropyl-prop-2-ynyloxy)-4,5-dimethoxy-benzaldehyde → 2-cyclopropyl-7,8-dimethoxy-2H-chromene-5-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

2.4 g of (RS)-3-(1-cyclopropyl-prop-2-ynyloxy)-4,5-dimethoxy-benzaldehyde were dissolved in 20 ml of N,N-diethyl-aniline, heated to 200° C. under argon and stirred at 200° C. for a further 1 hr. The solvent was distilled off at 90° C./1 mbar and the residue was extracted: 2×100 ml of diethyl ether, 2×100 ml of 1N HCl, 2×100 ml of saturated NaCl. The crude product was purified by two-fold silica gel chromatography with dichloromethane and, respectively, ethyl acetate/hexane 5:1. (RS)-2-Cyclopropyl-7,8-dimethoxy-2H-1-benzopyran-5-carbaldehyde was obtained as a brown oil (HPLC 96%).

Provenance & Evidence