Mild Ring Contractions of Cyclobutanols to Cyclopropyl Ketones via Hypervalent Iodine Oxidation

Abstract

An iodine-mediated oxidative ring contraction of cyclobutanols has been developed. The reaction allows the synthesis of a wide range of aryl cyclopropyl ketones under mild and eco-friendly conditions. A variety of functional groups including aromatic or alkyl halides, ethers, esters, ketones, alkenes, and even aldehydes are nicely tolerated in the reaction. This is in contrast with traditional synthetic approaches for which poor functional group tolerance is often a problem. The practicality of the method is also highlighted by the tunability of iodine oxidation system. Specifically, combining the iodine(III) reagent with an appropriate base allows the reaction to accommodate a range of challenging electron-rich arene substrates. The facile scalability of this reaction is also exhibited herein.

PhI(OTf)2 Does Not Exist (Yet)**

“…These observations, with triflic acid and triflic anhydride giving different products than the reaction of PhI=O with 2 TMS‐OTf, indicate that the intermediates generated in the TMS‐OTf reaction must differ. This is also consistent with reported reactions on the ring contraction of alcohol appended cyclobutanes where reaction of PhI(OAc) 2 with TMSOTf promoter gives a substantially different yield than the reaction of PhI(OAc) 2 or PhI=O with triflic anhydride as the promoter [6b] …”

Morita-Baylis-Hillman Reaction Inspired [3,3]-Rearrangement of Aryl Iodanes with α,β-Unsaturated Oxazolines

“…The reaction takes place via sequential three stages. After TMSOTf activates PhI(OAc) 2 to give PhI(OTf) 2 , [42][43][44][45] stage I generates an intermediate IM2 for the subsequent rearrangement process. The stage takes place by assembling PhI(OTf) 2 with E-3c to give EIM1, [46][47][48][49] followed by a MBH-like nucleophilic addition of 4-methylpyridine (denoted as Py) to an alkene carbon of EIM1.…”

Selective ortho C−H Cyanoalkylation of (Diacetoxyiodo)arenes through [3,3]‐Sigmatropic Rearrangement

“…To verify our hypothesis,w ec ommenced the study by treating PhI(OTf) 2 (formed in situ by the addition of TMSOTf to PhI(OAc) 2 ) [10] with several nitrile nucleophiles ( Table 1). Simple nitrile 2 did not provide any desired product when treated with PhI(OTf) 2 (entry 1).…”