The synthesis of a new family of 10-I-3 hypervalent iodine compounds is described in which the CF3 functionality participates directly in the hypervalent bond. These materials are accessible by nucleophilic ligand substitution at iodine using Me3SiCF3 in the presence of a substoichiometric amount of fluoride. The expected T-shaped geometry at iodine was verified by X-ray crystallographic analyses of three of the products (1-trifluoromethyl-1,2-benziodoxol-3-(1 H)-one and two substituted 1-trifluoromethyl-1,3-dihydro-1,2-benziodoxoles). Preliminary results for the direct electrophilic transfer of the trifluoromethyl moiety onto organic nucleophiles show modest reactivity in polar aprotic solvents under relatively mild conditions. The overall process can be understood as a formal umpolung of the CF3 group.

Novel 10‐I‐3 Hypervalent Iodine‐Based Compounds for Electrophilic Trifluoromethylation

Despite the fact that halogenation of alkenes has been known for centuries, enantioselective variants of this reaction have only recently been developed. In the past three years, catalytic enantioselective versions of halofunctionalizations with the four common halogens have appeared and although important breakthroughs, they represent just the very beginnings of a nascent field. This Minireview provides a critical analysis of the challenges that accompany the development of general and highly enantioselective halofunctionalization reactions. Moreover, the focus herein, diverges from previous reviews of the field by identifying the various modes of catalysis and the different strategies implemented for asymmetric induction.

Catalytic, Asymmetric Halofunctionalization of Alkenes—A Critical Perspective

The synthetic utility of organohypervalent iodine reagents will be illustrated by their use in the α-hydroxydimethylacetal formation reaction from enolizable ketones, α-hydroxylation, α-tosyloxylation, α-alkoxylation and arylation of ketones, carbon−carbon bond formation, and intramolecular cyclopropanation using iodonium ylides. The uses of these reagents in the Hunsdiecker reaction of carboxylic acids and Hofmann rearrangement of carboxamides is presented. Specific transformation in the cubane series are discussed. The syntheses of a wide range of heterocycle structures are also presented. A unifying pathway for virtually all these diverse reactions is offered; the central features being initial attack at the iodonium center, ligand coupling, with reductive elimination of iodobenzene to yield the product.

Organohypervalent iodine: development, applications, and future directions.

N-Heterocyclic carbenes (NHC) are nowadays ubiquitous and indispensable in many research fields, and it is not possible to imagine modern transition metal and main group element chemistry without t...

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry.

The synthetic utility of oxazolines in aromatic substitution

An electrically neutral .sigma.-sulfuranyl radical from the homolysis of a perester with neighboring sulfenyl sulfur: 9-S-3 species

The activation of various aromatic hydrocarbons by mercuration and thallation proceeds via ..pi..-complexes, as observed by the transient charge-transfer (CT) absorption spectra. Quantitative spectrophotometric analysis of (a) the association constants K and 9b) the second-order rate constants k/sub 2/ establishes the reactive forms of the electrophiles to be Hg(O/sub 2/CCF/sub 3/)/sub 2/ and Tl(O/sub 2/CCF/sub 3/)/sub 2//sup +/, both in ..pi..-complex formation as well as in aromatic metalation. The direct participation by these isoelectronic and isostructural species presents a unique opportunity to examine arene activation with electrophiles which primarily differ only in the charge they bear. A detailed comparison of the CT excitation energies and the reactivities of various arenes relative to steric, kinetic isotope, and solvent effects in mercuration and thallation reveals unusual similarities. At the same time the observation of arene cations as key intermediates in thallation, but not in mercuration, leads to puzzling incongruities. The paradox is analyzed in the context of merging stepwise (electron-transfer) and concerted (electrophilic) mechanisms.

Arene activation with mercury(II) and thallium(III) electrophiles. Mechanistic relevance of charge-transfer transitions in .pi.-complexes as intermediates

W. Lau

Papers

An electrically neutral .sigma.-sulfuranyl radical from the homolysis of a perester with neighboring sulfenyl sulfur: 9-S-3 species

Arene activation with mercury(II) and thallium(III) electrophiles. Mechanistic relevance of charge-transfer transitions in .pi.-complexes as intermediates