Protecting Group Sensitivity to Jones Oxidation

Although Jones oxidation is carried out in the presence of aqueous sulfuric acid, functionalities with a high sensitivity to acidic conditions can remain unchanged due to the segregation between the organic and aqueous phases. 

Only very acid-sensitive protecting groups are hydrolyzed under the conditions of the Jones oxidation. When free alcohols result from the hydrolysis of very acid-sensitive protecting groups, they are in situ oxidized to ketones or carboxylic acids. 

It must be mentioned that diverse acid strengths, temperatures and reaction times are used in Jones oxidation, which leads to uneven responses of the same protecting groups. 

Most silyl ethers, including the ubiquitous TBS ethers,22 resist Jones oxidation, with the exception of the very acid-sensitive TMS ethers.23 

Anomalous cases are known in which the normally robust TBS ethers are hydrolyzed.24 Contrastingly, rare instances have been published in which the sensitive TMS ethers remain unchanged25 under Jones oxdation. 

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