Regioselective Gold-Catalyzed Oxidative C–N Bond Formation

A novel protocol for the regioselective intermolecular amination of various arenes has been developed. By using an I­(III) oxidant in the presence of a Au­(I) catalyst, a direct and novel route for regioselectively accessing a variety of substituted aniline moieties has been achieved with yields as high as 90%. Mechanistic insight suggests that regioselectivity can be predicted based on electrophilic aromatic metalation patterns

Oxidative Cross-Coupling of sp³- and sp²‑Hybridized C–H Bonds: Vanadium-Catalyzed Aminomethylation of Imidazo[1,2‑<i>a</i>]pyridines

The vanadium-catalyzed oxidative coupling of substituted 2-arylimidiazo­[1,2-<i>a</i>]­pyridines to <i>N</i>-methylmorpholine oxide, which acts as both a coupling partner and an oxidant, has been achieved. This reaction was applied to various substituted imidiazo­[1,2-<i>a</i>]­pyridine and indole substrates, resulting in yields as high as 90%. Mechanistic investigations indicate that the reaction may proceed via a Mannich-type process. This work demonstrates how oxidative aminomethylation can be used as a useful method to introduce tertiary amines into heterocycles, thus providing an alternative method for conventional Mannich-type reactions

Cyclodextrin-Based Pseudorotaxanes: Easily Conjugatable Scaffolds for Synthesizing Hyperpolarized Xenon-129 Magnetic Resonance Imaging Agents

Hyperpolarized (HP) xenon-129 (Xe) magnetic resonance (MR) imaging has the potential to detect biological analytes with high sensitivity and high resolution when coupled with xenon-encapsulating molecular probes. Despite the development of numerous HP Xe probes, one of the challenges that has hampered the translation of these agents from in vitro demonstration to in vivo testing is the difficulty in synthesizing the Xe-encapsulating cage molecule. In this study, we demonstrate that a pseudorotaxane, based on a γ-cyclodextrin macrocycle, is easily synthesized in one step and is detectable using HyperCEST-enhanced ¹²⁹Xe MR spectroscopy