PhotoactivatedN‐Acyliminoiodinanes Applied to Amination: anortho‐Methoxymethyl Group Stabilizes Reactive Precursors

α-Amination of Carbonyl Compounds by Using Hypervalent Iodine-Based Aminating Reagents Containing a Transferable (Diarylmethylene)amino Group

Hypervalent iodine-based aminating reagents containing a transferable (diarylmethylene)amino group can be used for the α-amination of simple carbonyl compounds such as esters, amides, and ketones in the presence of a lithium base. The (diarylmethylene)amino groups of the products can be readily modified, thus providing access to primary amines and diarylmethylamines. The developed method features transition-metal-free conditions and a simple one-pot procedure without the need to prepare enolate equivalents separately, thus offering a general and practical approach to the synthesis of a wide variety of α-amino carbonyl compounds. Experimental mechanistic investigations indicate that this amination proceeds through a unique radical coupling of an α-carbonyl radical with an iminyl radical; they are generated through a single-electron transfer between a lithium enolate and the hypervalent iodine reagent.

RuV -Acylimido Intermediate in [RuIV (Por)Cl2 ]-Catalyzed C-N Bond Formation: Spectroscopic Characterization, Reactivity, and Catalytic Reactions

Metal-catalyzed C-N bond formation reactions via acylnitrene transfer have recently attracted much attention, but direct detection of the proposed acylnitrenoid/acylimido M(NCOR) (R=aryl or alkyl) species in these reactions poses a formidable challenge. Herein, we report on Ru(NCOR) intermediates in C-N bond formation catalyzed by [Ru^IV (Por)Cl₂ ]/N₃ COR, a catalytic method applicable to aziridine/oxazoline formation from alkenes, amination of substituted indoles, α-amino ketone formation from silyl enol ethers, amination of C(sp³ )-H bonds, and functionalization of natural products and carbohydrate derivatives (up to 99 % yield). Experimental studies, including HR-ESI-MS and EPR measurements, coupled with DFT calculations, lend evidence for the formulation of the Ru(NCOR) acylnitrenoids as a Ru^V -imido species.

β-Diazocarbonyl Compounds: Synthesis and their Rh(II)-Catalyzed 1,3 C-H Insertions

Herein, we describe the first electrophilic diazomethylation of ketone silyl enol ethers with diazomethyl-substituted hypervalent iodine reagents that gives access to unusual β-diazocarbonyl compounds. The potential of this unexplored class of diazo compounds for the development of new reactions was demonstrated by the discovery of a rare Rh-catalyzed intramolecular 1,3 C-H carbene insertion that led to complex cyclopropanes with excellent stereocontrol.

A Direct S0 →Tn Transition in the Photoreaction of Heavy-Atom-Containing Molecules

According to the Grotthuss-Draper law, light must be absorbed by a substrate to initiate a photoreaction. There have been several reports, however, on the promotion of photoreactions using hypervalent iodine during irradiation with light from a non-absorbing region. This contradiction gave rise to a mystery regarding photoreactions involving hypervalent iodine. We demonstrated that the photoactivation of hypervalent iodine with light from the apparently non-absorbing region proceeds via a direct S₀ →T_n transition, which has been considered a forbidden process. Spectroscopic, computational, and synthetic experimental results support this conclusion. Moreover, the photoactivation mode could be extended to monovalent iodine and bromine, as well as bismuth(III)-containing molecules, providing new possibilities for studying photoreactions that involve heavy-atom-containing molecules.

A Practical Aryliodine(I/III) Catalysis for the Vicinal Diamination of Styrenes

2,6-Disubstituted iodoarenes bearing amide-functionalized side arms are reported as new structures in redox-active iodine(I/III) catalysis. In combination with bis-sulfonimides as nitrogen sources and 3-chloroperbenzoic acid (mCPBA) as benign terminal oxidant they catalyze the vicinal diamination of styrenes. The obtained reactivity and selectivity outperform other iodoarene catalyst candidates. This protocol provides a sustainable alternative to previous related protocols for diamination that are based on stoichiometric iodine(III) reagents.