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

Since the publication of the proceedings of the Ljubljana symposium on hydrogen bonding by Hadzi [1] and the excellent book on the hydrogen bond by Pimentel and McClellan [2], a very large number of publications on the spectroscopic studies of hydrogen bonding have appeared in the literature. The present authors prepared a review on hydrogen bonding covering the period 1958–1963 for limited circulation [3]. In view of the very enthusiastic reception for this review by a number of workers and also the vast amount of published information on the subject after 1963, it was considered valuable to present an up-to-date review on the subject. The present review covers the period from 1958 to 1967 and embodies most of the studies on the hydrogen bond employing spectroscopic methods. The review does not include studies on crystals and macromolecules; hydrogen bonding in crystals has been recently reviewed by Hamilton and Ibers [4]. Electronic theories of the hydrogen bond have been reviewed by Bratoz [5]...

Spectroscopic studies of the hydrogen bond

Isolation, characterization, and reaction of the activated iodosylbenzene monomer, hydroxy(phenyl)iodonium ion, as a complex with 18-crown-6 (18C6) are reported. The reaction of iodosylbenzene with HBF(4) in the presence of 18C6 afforded the hydroxy-lambda(3)-iodane complex PhI(OH)BF(4).18C6 as stable yellow prisms. X-ray structure analysis indicated that the close contacts between the iodine(III) and the three adjacent oxygen atoms of 18C6 will be responsible for the increased stability of the complex compared to the uncomplexed PhI(OH)BF(4). The aqua complex of the activated iodosylbenzene, PhI(OH)OTf.18C6.H(2)O, with a water molecule coordinated to iodine(III) was also prepared. These crown ether complexes are highly reactive and serve as versatile stoichiometric oxidants, especially in water. Thus, the complexes undergo oxidative transformations of a variety of functional groups such as olefins, alkynes, enones, silyl enol ethers, sulfides, and phenols under mild conditions. The latter part reports on the iodobenzene-catalyzed alpha-oxidation of ketones, in which diacyloxy(phenyl)-lambda(3)-iodanes generated in situ act as real oxidants of ketones and m-chloroperbenzoic acid (m-CPBA) serves as a terminal oxidant. The oxidation of a ketone with m-CPBA in acetic acid in the presence of a catalytic amount of iodobenzene, BF(3)-Et(2)O, and water at room temperature affords an alpha-acetoxy ketone in good yield. It is noted that the use of water and BF(3)-Et(2)O is crucial to the success of this alpha-acetoxylation.

Stoichiometric and catalytic oxidations with hypervalent organo-lambda3-iodanes.

Organosulfonyloxy derivatives of 1,2-benziodoxol-3(1H)-one (3a−c) and 3,3-bis(trifluoromethyl)-3(1H)-1,2-benziodoxole (5a−c) can be prepared in high yield by the reaction of 1-hydroxybenziodoxoles 1 or 4 and the corresponding sulfonic acids or Me3SiOTf in the form of stable, but moderately hygroscopic, microcrystalline solids. Reaction of the triflate derivatives 3a and 5a with alkynyltrimethylsilanes affords either alkynyliodonium triflates 6, or (E)-β-(trifluoromethanesulfonyloxy)alkenyliodonium triflates 7, while the same reaction in the presence of pyridine selectively gives the respective 1-alkynylbenziodoxoles 8 and 9 in 82−90% yield.

1-(Organosulfonyloxy)-3(1H)-1,2-benziodoxoles: Preparation and Reactions with Alkynyltrimethylsilanes

1-(tert-Butylperoxy)-1,2-benziodoxol-3(1H)-one (1a) oxidizes benzyl and allyl ethers to the esters at room temperature in benzene or cyclohexane in the presence of alkali metal carbonates. Since this reaction is compatible with other protecting groups such as MOM, THP, and TBDMS ethers, and acetoxy groups, and because esters are readily hydrolyzed under basic conditions, this new method provides a convenient and effective alternative to the usual reductive deprotection. Oxidation with 1a occurs readily with C−H bonds activated by both enthalpic effects (benzylic, allylic, and propargylic C−H bonds) and/or polar effects (α-oxy C−H bonds), generating α-oxy carbon-centered radicals, which can be detected by nitroxyl radical trapping. Measurement of the relative rates of oxidation for a series of ring-substituted benzyl n-butyl ethers 2d and 2p−s indicated that electron-releasing groups such as p-MeO and p-Me groups increase the rate of oxidation, and Hammett correlation of the relative rate factors with the ...

Hypervalent (tert-Butylperoxy)iodanes Generate Iodine-Centered Radicals at Room Temperature in Solution: Oxidation and Deprotection of Benzyl and Allyl Ethers, and Evidence for Generation of α-Oxy Carbon Radicals

N. Sheppard

Papers

681. The structure of o-iodosobenzoic acid and of certain derivatives

178. Infrared spectra and hydrogen bonding in compounds containing X(:O).OH groups

566. An infrared absorption band of the N-methyl group in the region of 2800 cm.–1