Lithium iodide → (R)-(-)-3,4-Dihydro-2-(4-hydroxybenzyl)-2H-benzopyran

Participants

Reaction Steps

(R)-(-)-3,4-Dihydro-2-(4-methoxybenzyl)-2H-benzopyran (812 mg, 3.2 mmol), and lithium iodide (750 mg, 5.6 mmol) were dissolved in 2,4,6-collidine (2 ml) and heated to reflux for 24 hours. The reaction mixture was cooled, diluted with ethyl acetate (20 ml) and 10% HCl (20 ml), and stirred for 10 minutes. The layers were separated and the aqueous portion was extracted with ethyl acetate (50 ml). The combined organics were washed with water (20 ml), brine (20 ml), and were dried MgSO4). The solvent was removed in vacuo and the residue purified on silica gel using hexanes/ethyl acetate (3:1) as eluent to afford 730 mg of a colorless oil which crystallized upon standing, mp 60°-62° C.; [α]D -110.2° (c 1.0, MeOH); 1H NMR (300 MHz, CDCl3) δ1.7 (m, 1H), 2.0 (m, 1H), 2.7-2.8 (m, 3H), 3.1 (dd, 1H), 4.2 (m, 1H), 6.8 (m, 3H), 7.0-7.2 (m, 4H).

Provenance & Evidence