4-Toluenesulfonyl chloride → (2R)-3,4-dihydro-2H-benzo[h]chromen-2-ylmethyl 4-methylbenzenesulfonate

Participants

Reaction Conditions

Reaction Steps

To a solution of (2R)-3,4-dihydro-2H-benzo[h]chromen-2-ylmethanol (0.90 g, 4.22 mmol) in dichloromethane (50 mL) is added p-toluenesulfonyl chloride (1.61 g, 8.44 mmol), 4-(dimethylamino)pyridine (0.10 g, 0.84 mmol), and N,N-diisopropylethylamine (1.20 g, 9.28 mmol) and the reaction mixture is heated to 50° C. for 12 h. The reaction mixture is quenched by the addition of water (100 mL). The aqueous layer is separated and extracted with dichloromethane (100 mL). The combined organic extracts are washed with aqueous hydrogen chloride (1.0 M, 100 mL), water (100 mL), aqueous sodium chloride (100 mL), dried (magnesium sulfate), and the solvent is removed in vacuo to provide a crude solid. Purification by flash column chromatography (silica, ethyl acetate:hexanes 2:3) provides 1.20 g (77%, 50% ee) of (2R)-3,4-dihydro-2H-benzo[h]chromen-2-ylmethyl 4-methylbenzenesulfonate as a white solid. [α]D25=−10.23 (c 10.16 in chloroform, 50% ee); Rf=0.68 (silica, ethyl acetate:hexanes 2:3); mp 107-111° C.; Anal. Calcd. for C21H20O4S: C, 68.46; H, 5.47. Found: C, 68.10; H, 5.27.

Provenance & Evidence