Bipyridinium chlorochromate alcohols

Dicarboxypyridinium chlorochromate (2,6-DCPCC)392 possesses an acidic character that allows the in situ deprotection and oxidation of alcohols, protected as tetrahydropyranyl and trimethylsilyl ethers. 2,2 -Bipyridinium chlorochromate (BPCC)393 contains a ligand that complexes efficiently with the reduced chromium species, generated during the oxidation of alcohols, allowing for a substantial simplification of the work-ups. For this reason, it enjoys a popularity among chlorochromates surpassed by only PCC. 

From the temperature dependence of the substantial kinetic isotope effect (KIE) observed in the oxidation of diols to hydroxycarbonyl compounds by 2,2/-bipyridinium chlorochromate (BPCC), it is proposed that hydride transfer occurs in a chromate ester intermediate, involving a six-electron Hiickel-type transition state.9 A similar conclusion is drawn for the oxidation of substituted benzyl alcohols by quinolinium chlorochromate.10... 

Bipyridinium chlorochromate (4) is a mild, air stable nonhygroscopic oxidant. It is weaker than PCC, and thus 2-4 equiv. are required to obtain good yields of carbonyl compounds. The bipyridyl system acts as an internal buffer, permitting the ready oxitktion of alcohols in sul trates with acid labile groups. Bipyridinium chlorochromate will also oxidize sulfides to sulfoxides and sulfones." ... 

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