rac-5-[(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-yl)ethynyl]-2-hydroxybenzoic acid methyl ester → rac-5-[2-(3,4-Dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-yl)ethyl]-2-hydroxybenzoic acid methyl ester

Participants

Reaction Steps

A mixture of 0.7 g of rac-5-[2-(3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-yl)ethynyl]-2-hydroxybenzoic acid methyl ester, 0.2 g of 5% palladium on carbon and 20 ml of methanol was hydrogenated at atmospheric pressure for 4 hours. The catalyst was separated by filtration and the filtrate was evaporated. The residue was passed over 10 g of silica gel (70-230 mesh) using methylene chloride. The product was crystallized from ether/hexane to give 0.5 g of colorless crystals with m.p. 108°-110°.

Provenance & Evidence