2-Cyclopropyl-7,8-dimethoxy-2H-chromene-5-carboxylic acid methyl ester → 2-Cyclopropyl-7,8-dimethoxy-2H-1-benzopyran-5-methanol

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Reaction Conditions

Reaction Steps

Methyl ester 2 (2 g, 6.2 mmol) was dissolved in 30 ml tetrahydrofurane and 2.7 ml of a 3.5-M solution of Red-Al (9.4 mmol) was added. The mixture was stirred at 40° C. for 3 hours. The solution was diluted with 100 ml of TBME and slowly quenched by addition of 50 ml of a 30% potassium-tartrate solution. The layers were separated and the organic solution was washed with brine (2 times 30 ml), dried over magnesium sulfate and concentrated. The pure alcohol 4 (1.34 g, 5.1 mmol) was obtained as a white-yellow solid.

Provenance & Evidence