Assessing the effectiveness of oxidative approaches for the synthesis of aldehydes and ketones from oxidation of iodomethyl group

Owing to excellent selectivity, high yield and stability towards over-reduction and over-oxidation, one of the impressive approaches to synthesize aldehydes and ketones is the oxidation of halomethyl groups. Numerous halomethyl oxidation-based methodologies to afford aldehydes and ketones are disclosed in the literature. Mostly, chloromethyl or bromomethyl group containing substrates have been used in the literature for performing oxidation. There are negligible data available in the literature that addresses the use of iodomethyl group containing substrates for transformation to aldehydes and ketones. In this research work, 110 reactions have been carried out to construct aldehydes and ketones from oxidation of iodomethyl group in benzylic iodides and allylic iodides using numerous well-known approaches reported in the literature. The classical approaches under observation include Sommelet oxidation, Kröhnke oxidation, sodium periodate-mediated oxidative protocol, manganese dioxide-based oxidative approach, Kornblum oxidation and Hass–Bender oxidation. The eco-friendly approaches under observation include periodic acid-based IL protocol, periodic acid in vanadium pentoxide-mediated IL method, hydrogen peroxide in vanadium pentoxide-based approach and bismuth nitrate-promoted IL technique. In this investigation, yield, recyclability, cost-effectiveness, eco-friendliness and over-oxidation are the main parameters which are under observation. Among all these investigated techniques, periodic acid-based IL protocol, periodic acid in vanadium pentoxide-mediated IL method and hydrogen peroxide in vanadium pentoxide-based approach (aka. Chunbao oxidation protocol) were found to be highly efficient due to the following reasons: these approaches (1) provide excellent yields, (2) do not lead towards over-oxidation, (3) show good recyclability, (4) demonstrate high thermal stability and negligible flammability, and (5) require no special handling.