3,4-dihydro-2H-pyran → Tetrahydropyranyl ether

Participants

Reaction Conditions

Reaction Steps

A suspension of triphenol 3 (164 g, 0.672 mol) in 3, 4dihydro-2H-pyran (600 mL) (available from Aldrich Chemical Company Inc., Milwaukee, Wis.) was treated with p-toluenesulfonic add monohydrate (2×10 mg) at 0° C. The reaction mixture was stirred for 1.5 h at 0° C. and then for 1 h after removing the ice bath (the reaction was monitored by TLC; p-toluenesulfonic acid monohydrate was added until starting material and monotetrahydropyranyl ether had disappeared). The mixture was then treated with saturated sodium bicarbonate (250 mL) and ethyl acetate (1 L). The organic phase was washed with saturated sodium bicarbonate (250 mL) and brine (250 mL), dried over magnesium sulfate and evaporated under reduced pressure. The crude compound was triturated with hexanes (2 L) for 3 h with stirring. The resulting suspension was left to stand at 0° C. for 5 h and then at -20° C. for 18 h. The solid was filtered and treated again with hexanes (1 L) with stirring for 1 h to give compound 4 which was filtered and dried (190 g, 69%), mp 109-112° C.: 1H-NMR δ (300 MHz: CDCl3), 1.5-2.1 (12H, m, O CH--CH2 --CH2 --CH2 --CH2 --O), 3.55-3.65 (2H, m, O--CH--CH2 --CH2 --CH2 --CH2O), 3.75-3.95 (2H, m, O--CH--CH2 --CH2 --H2 --CH2O), 4.16 (2H, s, Ph--CH2C=O), 5.40 (1H, t, J=3 Hz, O--CH--CH2 --CH2 --CH2 --CH2 --O), 5.49 (1H, t, J=3 Hz, O--CH--CH2 --CH2 --CH2 --CH2 --O), 6.55 (1H, dd, J=2.5 Hz and 8.5 Hz, CH phenyl), 6.61 (1H, d, J=2.5 Hz, CH phenyl), 7.03 and 7.17 (2H, AB system, J=8.5 Hz, CH phenyl), 7.77 (1H, d, J=8.5 Hz, CH phenyl), 12.60 (1H, s, Ph OH).

Provenance & Evidence