Parikh-Doering oxidation sensitivity

Functional Group and Protecting Group Sensitivity to Parikh-Doering Oxidation... 

The Parikh-Doering oxidation provides a very high regioselectivity for the oxidation of alcohols. Oxidation-sensitive functionalities, like indoles,99a,c sulfides,109 and selenides 110 as well as oxidation-sensitive protecting groups, like dithioacetals,111 PMB104 and dimethoxybenzyl ethers109b, do not react. 

It must be mentioned that sensitive compounds, like alkyl silanes,112 alkyl stannanes113 and vinyl stannanes,114 are not affected under the conditions of the Parikh-Doering oxidation. 

Peptide aldehydes 1 can be synthesized effectively by the oxidation of peptide alcohols 15, which are readily available without racemization by reduction of peptide esters 9 with sodium borohydride-lithium chloride (Scheme 5). The peptide alcohols 15 can be readily oxidized to afford enantiomerically pure aldehydes using Parikh-Doering or Dess-Martin reagents. This route is less popular than the previously described reductive methods due to (1) the sensitivity of the aldehydes to further oxidation, (2) racemization under the reaction conditions, and (3) instability of the products under the reaction conditions. 

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