Kei Goto

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSynthesis, Structure, and Reactions of a Sulfenic Acid Bearing a Novel Bowl-Type Substituent: The First Synthesis of a Stable Sulfenic Acid by Direct Oxidation of a ThiolKei Goto, Michel Holler, and Renji OkazakiView Author Information Department of Chemistry, Graduate School of Science The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan Cite this: J. Am. Chem. Soc. 1997, 119, 6, 1460–1461Publication Date (Web):February 12, 1997Publi

The deep cavity in the calix[6]arene framework provides a sterically shielded environment for the SeOH group of the selenenic acid 1. Thanks to this shielding the compound is extraordinarily stable—no decomposition was observed even after heating at 120°C for 5 h in CDCl2CDCl2—although the functional group is still reactive.

A wealth of highly selective reactions may become accessible thanks to the approach described herein: A reactive functional group is placed on the inside of a bowl-shaped molecular skeleton; in this way, for example, dimerizations can be prevented, but reactions with added small molecules remain possible. The sulfenic acid 1 obtained from the corresponding S-butyl sulfoxide by pyrolysis is stable both in the solid state and in solution, and reacts smoothly with methyl propiolate and butanethiol.

[structure: see text]. A stable selenenic acid was synthesized by direct oxidation of a selenol bearing a novel bowl-type substituent with H2O2, and its structure was established by X-ray crystallographic analysis. Selenenyl sulfides obtained by the reaction of the selenenic acid with 1,4-dithiols were reduced to the corresponding selenol by treatment with a tertiary amine, thus achieving the experimental demonstration of three processes included in the catalytic cycle of glutathione peroxidase.

What makes a good cavity? A molecular cavity enabled the stabilization of a selenenyl iodide (RSeI) intermediate formed in 5′-deiodination of a thyroxine derivative by an organoselenol (see scheme). The chemical processes proposed for the iodothyronine deiodinase catalytic cycle were experimentally established.

Although selenocysteine selenenic acids (Sec-SeOHs) have been recognized as key intermediates in the catalytic cycle of glutathione peroxidase (GPx), examples of the direct observation of Sec-SeOH in either protein or small-molecule systems have remained elusive so far, mostly due to their instability. Here, we report the first direct spectroscopic (¹H and ⁷⁷Se NMR) evidence for the formation of Sec-SeOH in small-molecule selenocysteine and selenopeptide model systems with

Abstract Endohedral phases of molecular bowls and capsules have great potential for serving as a reaction environment for the internal functionality as well as a complexing site for the guest molecule. The reactivity of a functional group covalently fixed in the interior of such molecules can be regulated in a unique fashion by the surrounding framework. This article gives an account of the design of novel molecular bowls and capsules bearing an endohedral functionality and the stabilization of

An arenesulfenyl iodide with unprecedented stability was synthesized by oxidation of a thiol bearing a novel bowl-type substituent with iodine, whose monomeric structure was determined by X-ray crystallographic analysis.

Abstract A stable aromatic S-nitrosothiol was synthesized by taking advantage of a novel dendrimer-type steric protection group, and its structure was determined by X-ray crystallographic analysis. Its reactions including oxidation to a stable S-nitrothiol are described.

Abstract Alkaline hydrolysis of a thionitrate and a sulfenyl bromide bearing a bowl-type steric protection group produced a stable sulfenic acid. This provides a conclusive demonstration of these elementary processes. It was shown that a very efficient steric protection group is necessary to prevent the condensation of the sulfenate anion generated during the hydrolysis.

The unprecedented dehydration of a selenenic acid (RCH2SeOH) to a selenoaldehyde (RCH=Se) has been demonstrated. A primary-alkyl-substituted selenenic acid was synthesized for the first time by taking advantage of a bulky cavity-shaped substituent. Upon heating in solution, the selenenic acid underwent thermal dehydration to produce a stable selenoaldehyde, which was isolated as stable crystals and crystallographically characterized. Investigation of the reaction mechanism revealed that this β d