Hydrochloric Acid → Isochroman-3-ol

Participants

Reaction Conditions

Reaction Steps

To a solution of 3.00 g (0.020 mol) of 1,4-dihydro-3H-2-benzopyran-3-one in 100 mL of dry dichloromethane, cooled to -78° C., was added dropwise, over 1 hour, 24 mL (0.022 mol) of a 1M solution of disobutyl aluminum hydride in dichloromethane. After stirring at -78° C. for 2 hours and at 0° C. for 15 minutes, 100 mL of ether was added, followed by dropwise addition of 1.2N HCl until a pH of 1-2 was reached. Separation of the organic phase, extraction of the aqueous phase with ether and concentration of the combined dried (MgSO4) extracts provided 2.8 g (91%) of 3,4-dihydro-1H-2-benzopyran-3-ol. This product decomposes on standing or on chromatography on silica gel and consequently was used directly for the next reaction step. TLC Rf 0.13 (SiO2, CH2Cl2, brown-orange CAS and heat).

Provenance & Evidence