The aerobic oxidative coupling of arenes such as benzofuran and N-substituted indoles with benzene and derivatives thereof is described. The reaction is shown to take place in both inter-and intramolecular scenarios.Biaryls are common substructures in high value molecules such as organic dyes, conducting polymers, asymmetric ligands, and pharmaceuticals.
The development of a novel intermolecular oxidative amination reaction, a synthetic transformation that involves the simultaneous functionalization of both an N-H and C-H bond, is described. The process, which is mediated by an I(III) oxidant and contains no metal catalysts, provides a rapid and green method for synthesizing protected anilines from simple arenes and phthalimide. Mechanistic investigations indicate that the reaction proceeds via nucleophilic attack of the phthalimide on an aromatic radical cation, as opposed to the electrophilic aromatic amination that has been reported for other I(III) amination reactions. The application of this new reaction to the synthesis of a variety of substituted aniline derivatives is demonstrated.
The most direct method for synthesizing 2-arylindoles is the oxidative coupling of an arene with an indole. We have shown that both the activity and regioselectivity of these cross-coupling reactions are correlated to the acidity of the medium. This insight has been applied to predict the best conditions for the oxidative cross-coupling of N-alkylindoles, an important class of substrates that was heretofore incompatible with the harsh conditions required for oxidative cross-coupling. Both experimental and computational data indicate that the mechanism for C-H palladation of both the indoles and simple arenes is best described as concerted metalation-deprotonation (CMD), regardless of the substitution on the arenes.
The Hyperpolarized gas Chemical Exchange Saturation Transfer (HyperCEST) Magnetic Resonance (MR) technique has the potential to increase the sensitivity of a hyperpolarized xenon-129 MRI contrast agent. Signal enhancement is accomplished by selectively depolarizing the xenon within a cage molecule which, upon exchange, reduces the signal in the dissolved phase pool. Herein we demonstrate the in vivo detection of the cucurbit[6]uril (CB6) contrast agent within the vasculature of a living rat. Our work may be used as a stepping stone towards using the HyperCEST technique as a molecular imaging modality.
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