Iodine(V) Reagents in Organic Synthesis. Part 4. <i>o</i>-Iodoxybenzoic Acid as a Chemospecific Tool for Single Electron Transfer-Based Oxidation Processes
作者:K. C. Nicolaou、T. Montagnon、P. S. Baran、Y.-L. Zhong
DOI:10.1021/ja012127+
日期:2002.3.1
o-Iodoxybenzoic acid (IBX), a readily available hypervalent iodine(V) reagent, was found to be highly effective in carrying out oxidations adjacent to carbonyl functionalities (to form alpha,beta-unsaturated carbonyl compounds) and at benzylic and related carbon centers (to form conjugated aromatic carbonyl systems). Mechanistic investigations led to the conclusion that these new reactions are initiated
cyclooctatetraenes, bridged with methylene groups in a previously unknown 1,3-manner, have been prepared in racemic form by a route involving ultimate disrotatory opening of a suitably constructed bicyclo[4.2.0]octatriene precursor.
Treatment of α-bromo-α,β-unsaturatedketones of 1,1-dibromo-2-trimethylsiloxycyclopropanes with diethyl phosphite and triethylamine affords β,γ-unsaturated ketones selectively.
The three-carbon ringexpansion methodology commences with the preparation of a cyclic allene (C9, C11, C13), readily available from the corresponding cycloalkene via dibromocarbene addition and subsequent treatment with methyllithium. Dichloroketene addition to the cyclic allene regioselectively provides the [2+2] cycloadduct which is reductively dechlorinated with zinc in methanol. The resulting