Sodium Sulfite → 9-cis-4-Oxoretinoic acid

Participants

Reaction Steps

To a solution of 4-hydroxy-9-cis-retinoic acid (16 mg, 0.05 mmole) in CH2Cl2 (1.5 ml) was added Dess-Martin reagent [see Dess and Martin in J. Org. Chem. 48:4155 (1983)] (42 mg, 0.1 mmole) in one portion at 25° C. After stirring for 5 minutes, the mixture was diluted with 10 ml of ether and to this was added saturated aqueous NaHCO3 (5 ml) containing Na2SO3 (55 mg). The mixture was stirred for 20 minutes to dissolve the solid and the layers separated. The ether layer was washed with H2O (2×5 ml), brine (5 ml) and dried (MgSO4). The solvent was recovered under reduced pressure and residue was subjected to flash column chromatography (silica, 60% ether in Hexane) to give 4-keto-9-cis-retinoic acid (14 mg. 90%), characterized as follows: TLC rf=0.6 (silica, 80% ether in hexane); 1HNMR (400 mHz, CDCl3) δ 7.05 (dd, J=16, 12 Hz, 1H, olefinic), 6.82 (d, J=16 Hz, 1 H, olefinic), 6.32 (d, J=16 Hz, 1H, olefinic), 6.30 (d, J=16 Hz, 1H, olefinic), 6.20 (d, J=12 Hz, 1H, olefinic), 5.80 (s, 1H, olefinic), 2.5 (t, J=7 Hz, 2H, CH2 --CO), 2.31 (S, 3H, CH3), 2.01 (s, 3H, CH3), 1.9 (s, 3H, CH3), 1.89 (m, 2H, CH2), 1.20 (s, 6H, 2×CH3).

Provenance & Evidence