1202643-83-1Relevant articles and documents
Mild Ring Contractions of Cyclobutanols to Cyclopropyl Ketones via Hypervalent Iodine Oxidation
Sun, Yan,Huang, Xin,Li, Xiaojin,Luo, Fan,Zhang, Lei,Chen, Mengyuan,Zheng, Shiya,Peng, Bo
, p. 1082 - 1087 (2018)
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. (Figure presented.).
Terminal Trifluoromethylation of Ketones via Selective C-C Cleavage of Cycloalkanols Enabled by Hypervalent Iodine Reagents
Wu, Shuang,Li, Junzhao,He, Ru,Jia, Kunfang,Chen, Yiyun
supporting information, p. 9204 - 9209 (2021/11/30)
We report the first terminal trifluoromethylation at aryl and alkyl ketones' ?, or more remote sites via the selective C-C bond cleavage of cycloalkanols. The noncovalent interactions between alcohols and hypervalent iodines(III) reagents were disclosed to activate both alcohols and the Togni I reagent in the dual photoredox/copper catalysis for the transformation. This reaction was scalable to the gram-scale synthesis, applicable to the structurally complex steroid trifluoromethylation, and extendable to the pentafluoroethylation.
Regio- and Stereoselective Rhodium(II)-Catalyzed C–H Functionalization of Cyclobutanes
Garlets, Zachary J.,Wertz, Benjamin D.,Liu, Wenbin,Voight, Eric A.,Davies, Huw M.L.
supporting information, p. 304 - 313 (2020/01/08)
Recent developments in controlled C–H functionalization transformations continue to inspire new retrosynthetic disconnections. One tactic in C–H functionalization is the intermolecular C–H insertion reaction of rhodium-bound carbenes. These intermediates can undergo highly selective transformations through the modulation of the ligand framework of the rhodium catalyst. This work describes our continued efforts toward differentiating C–H bonds in the same molecule by judicious catalyst choice. Substituted cyclobutanes that exist as a mixture of interconverting conformers and possess neighboring C–H bonds within a highly strained framework are the targets herein for challenging the current suite of catalysts. Although most C–H functionalization tactics focus on generating 1,2-disubstituted cyclobutanes via substrate-controlled directing-group methods, the regiodivergent methods discussed in this paper provide access to chiral 1,1-disubstituted and cis-1,3-disubstituted cyclobutanes simply by changing the catalyst identity, thus permitting entry to novel chemical space. This study shows how to control site selectivity in C–H functionalization by simply using the correct catalyst. Cyclobutanes were used as the scaffold to illustrate the impact of catalyst control because the core unit is incorporated into various structures of biomedical interest. The catalysts control whether the chemistry occurs at C1 or C3 of the cyclobutane. Traditional synthetic strategies have viewed most C–H bonds as chemically inert and utilize functional groups for transformations. C–H functionalization is an attractive alternative strategy for the synthesis of complex organic molecules because it leads to the possibility of rapidly accessing novel chemical space. To fully develop this alternative approach, it is necessary to identify ways for reacting at specific C–H bonds even when a number of similar C–H bonds may exist in a substrate molecule. It would be particularly beneficial if a collection of catalysts were available, each with a preference for reaction at a specific C–H bond. Over the past few years, we have developed such a collection of catalysts for C–H functionalization chemistry of rhodium-bound carbenes. In this paper, we illustrate how these catalysts can be applied to the selective functionalization of cyclobutanes, leading to the formation of pharmaceutically relevant chiral building blocks.
