Catalytic Oxidative 1,2-Shift in 1,1′-Disubstituted Olefins Using Arene(iodo)sulfonic Acid as the Precatalyst and Oxone as the Oxidant

Abstract

An efficient, catalytic hypervalent iodine-mediated oxidative 1,2-shift of 1,1'-disubstituted olefins is described. This methodology provides concise access to homobenzylic ketones with electron-donating substituents. In the case of cyclic systems, this transformation results in ring-expanded β-benzocycloalkanones, which are useful for further elaboration.

Enantioselective Oxidative Rearrangements with Chiral Hypervalent Iodine Reagents

“…The employment of catalytic amounts of iodine reagent in combination with an external oxidant for hypervalent iodine‐mediated transformations is an active area of research . It has been shown that electron‐rich 1‐alkyl‐1‐arylethenes can rearrange to ketones with sub‐stoichiometric quantities of 4‐methyl‐iodobenzenesulfonic acid . We found that more electron‐rich 1,1‐diarylalkenes, such as 6 a , suffered from direct reaction with the terminal oxidants in preference to the iodine(I)→iodine(III) oxidation of chiral iodoarenes.…”

Recent Advances in Transition‐Metal‐Free Oxygenation of Alkene C=C Double Bonds for Carbonyl Generation

“…Inspired by the pioneering work of Koser et al. on the hypervalent iodine‐promoted ketone synthesis that involves bond rearrangement, Purohit and co‐workers developed rearrangement‐based oxygenation reactions of terminal alkenes 73 for the synthesis of ketone products 74 through iodine(III) catalysis. In this procedure, iodobenzenesulfonic acid 75 was employed as precatalyst that was transformed into iodine(III) catalyst 76 in the presence of the terminal oxidant oxone.…”

Rearrangements Induced by Hypervalent Iodine

“…When treated with a sub-stoichiometric amount of 2-iodo-5-methylbenzenesulfonic acid 55 as a pre-catalyst and in the presence of Oxone® as a co-oxidant, olefin 54 is transformed into the corresponding ketone 56 as shown in Scheme 17 [13]. It should be stressed that those conditions imply only 80 mol% of Oxone®, in order to generate a reactive iodine species(III) and not to overoxidize the reagent into an iodine(V), which would probably be unable to promote the desired transformation.…”