Oxidation of benzylic alcohols

[demorol]

Oxidation and Bromodehydroxymethylation of Benzylic Alcohols using NaBrO₃/NaHSO₃ Reagent (Bull. Korean. Chem. Soc. 2002, Vol. 23, pp 1667)

General procedure

To a stirred solution of alcohol (5 mmol) in aqueous acetonitrile (30mL, 1:1 by volume) was added NaBrO₃ (1.51g, 10 mmol) and NaHSO₃ (1.04g, 10 mmol). Reactions were continuously monitired by TLC and stirred at room temperature for the time indicated in Table 1. The reaction mixture was quenched with aqueous sodium thiosulfate and extracted with ether (3 × 30mL). The combined organic layers were washed with aqueous Na₂CO₃, water, dried over MgSO₄, filtered and concetrated in vacuo. The residue was chromatographed on a silica gel column and eluted with hexane-EtOAc (10:1) to give aldehyde or aryl bromide (Table 1). The combined aqueous layer was acidified with 10% HCl to pH 2 and extracted with EtOAc (2 × 50mL). The organic layers were washed with water, dried and evaporated to afford the products.

[Aurelius]

Great! so, what is the product?  the aldehyde or the halide?  (i can't see the pic)  how do you influence the formation of one or the other?

[zorohydride]

I have used the above mentioned reagent with great ease to effect oxidation of benzyl alcohols to the corrsponding ketone. It requires a little clean up and DCM is the preferred solvent for reaction. Sigma-Aldrich has lots of good info RE:the reagent. Here is an enclosed link to a different site:

http://www.csbsju.edu/chemistry/OrganicChemPages/cps4.html