Reacción #1052151

Ecuación de reacción

methyl (RS)-3-(1-cyclopropyl-prop-2-ynyloxy)-4,5-dimethoxy-benzoate

→

Methyl (RS)-2-cyclopropyl-7,8-dimethoxy-2H-1 -benzopyran-5-carboxylate

Disolventes

N,N-diethylaniline

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.DISTILLATIONThe solvent was distilled off at 90° C./1 mbar
2. 2
   Extracciónthe residue was extracted
3. 3
   OtroThe oil obtained
4. 4
   Otrowas purified by silica gel chromatography with toluene
5. 5
   OtroCrystallization

Procedimiento

33.5 g of methyl (RS)-3-(1-cyclopropyl-prop-2-ynyloxy)-4,5-dimethoxy-benzoate were dissolved in 330 ml of N,N-diethylaniline, heated to 200° C. under argon and stirred at 200° C. for a further 5 hrs. The solvent was distilled off at 90° C./1 mbar and the residue was extracted: 2×1.5 l of diethyl ether, 2×1.5 l of 1N HCl, 2×1.5 l of saturated NaCl. The oil obtained was purified by silica gel chromatography with toluene, then toluene/ethyl acetate 9:1. Crystallization was effected from diethyl ether and hexane. Methyl (RS)-2-cyclopropyl-7,8-dimethoxy-2H-1 -benzopyran-5-carboxylate was obtained as white crystals.

Fuente