Acetic Anhydride → (R)-(-)-2-(4-Acetoxybenzyl)-3,4-dihydro-2H-benzopyran

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Reaction Steps

(R)-(-)-3,4-Dihydro-2-(4-hydroxybenzyl)-2H-benzopyran (5.0 g, 20 mmol), 4-dimethylaminopyridine (240 mg, 2 mmol), triethylamine (2.6 g, 25 mmol) and acetic anhydride (2.9 g, 28 mmol) were dissolved in methylene chloride (75 ml) and stirred at room temperature for 2 hours under a nitrogen atmosphere. The solvent was removed in vacuo and the residue purified on silica gel using hexanes/ethyl acetate (3:1) as eluent to afford an oil which was crystallized from hexanes to yield 4.0 g of the title product, m.p. 64°-65° C.; [α]D -98.9° (c 1.3, MeOH);

Provenance & Evidence