6-Bromochroman-2-one → 6-Bromo-2-chromanol

Participants

Reaction Steps

To a mixture of 16.4 g (72.2 mmole) 6-bromo-2chromanone and 60 ml dry tetrahydrofuran, under nitrogen at -70° C., was added a cloudy solution of 18.4 g (72.2 mmole) lithium hydrido-tri(t-butoxy)aluminate (commercial) over 30 minutes. The mixture was stirred while allowing it to warm to room temperature over 90 minutes, then poured onto 250 ml ice/water. The resulting mixture was filtered, the cake washed with ethyl ether, then ethyl acetate and the organic phase is separated. The aqueous layer is extracted with ethyl acetate, the organic layers combined, dried (Na2SO4) and solvent evaporated to obtain 9.5 g crude product. An additional 4 g was obtained by reworking the filter cake, above. The combined crude products were purified on a silica gel column, eluting with 9:1 hexane/ethyl acetate, then a 4:1 mixture of the same solvents to obtain the purified product as an oil, 5.6 g.

Provenance & Evidence