Treatment of a 1,2-dichloroethane solution of various alcohols with iodosylbenzene in the presence of a catalytic amount of ytterbium(III) nitrate provided the corresponding carbonyl compounds in good to excellent yields.
The benzoylation of various classes of diols by means of diethyl azodicarboxylate (1) and triphenylphosphine (2) was carried out at room temperature. When primary–secondary diols were treated with an equimolar amount of benzoic acid (3) in the presence of 1.5 molar equivalents of 1 and 2, reaction mainly Occurred at their primary hydroxyl functions. Secondary–secondary diols gave mono- and dibenzoylated products or cyclic ethers. The course of the reactions depends on the structure of diols used. Thus, intermolecular displacement giving benzoates is a favorable process for 1,3-butanediol, 2,4-pentanediol and trans-1,2-indanediol, while 2,5-hexanediol and trans-1,2-cyclohexanediol afford the cyclized products.
Hypervalent iodine(III)/Et4N+Br− combination in water for green and racemization-free aqueous oxidation of alcohols
作者:Naoko Takenaga、Akihiro Goto、Misaki Yoshimura、Hiromichi Fujioka、Toshifumi Dohi、Yasuyuki Kita
DOI:10.1016/j.tetlet.2009.02.020
日期:2009.7
We have found that the use of the Phl(OAc)(2)/Et4N+Br combination in water can significantly enhance its oxidation ability and oxidize a wide range of alcohols 1 to carbonyl compounds 2 in good to excellent yields. This clean aqueous oxidation method shows no detectable racemization processes, and even an enolizable ketone 2m Could be obtained in an optically pure form from the corresponding chiral alcohol 1m. Utilization of the recyclable reagent 3 as a more practical alternative to Phl(OAc)(2) is also Successful in these reactions. (C) 2009 Elsevier Ltd. All rights reserved.
Facile and Clean Oxidation of Alcohols in Water Using Hypervalent Iodine(III) Reagents
作者:Hirofumi Tohma、Shinobu Takizawa、Tomohiro Maegawa、Yasuyuki Kita