Formaldehyde → 6-Methoxy-3,4-dihydro-1H-2-benzopyran-1-one

Beteiligte Stoffe

Reaktionsschritte

A 1.6M solution of n-butyllithium in hexane (145.9 mL) was added dropwise to a solution of diisopropylamine (33.5 mL) in dry THF (190 mL) at −78° C. The reaction mixture was then warmed to room temperature for 5 min and again cooled to −78° C., and a solution of 4-methoxy-2-methylbenzoic acid in dry THF (210 mL) was added dropwise. After stirring at this temperature for 10 min, paraformaldehyde (7 g) was added. The reaction mixture was then allowed to reach room temperature and was stirred at this temperature for 4 h. Water was added to the reaction mixture, and then the THF was removed in vacuo and the aqueous phase was extracted with diethyl ether. The aqueous phase was acidified with conc. HCl, and the resulting precipitate was filtered off and washed with water several times. The product with the molecular weight of 178.06 (C10H10O3) was obtained in this way; MS (ESI): 179 (M+H+).

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