A Convenient Halogenation of α,β-Unsaturated Carbonyl Compounds with<i>OXONE</i>
<sup>®</sup>and Hydrohalic Acid (HBr, HCl)
作者:Kyoung-Mahn Kim、In-Hwan Park
DOI:10.1055/s-2004-831232
日期:——
Mixtures of OXONE ® and hydrobromic acid or hydrochloric acid afford solutions of bromine or chlorine, respectively. α-Bromo- or α-chloro-α,β-unsaturated carbonyl compounds were prepared by addition of hydrobromic acid or hydrochloric acid to the mixture of α,β-unsaturated carbonyl compounds and OXONE ® in CH2Cl2 followed by treatment of Et3N in moderate to good yields.
Oxidation of α,β-enones and alkenes with oxone and sodium halides: A convenient laboratory preparation of chlorine and bromine
作者:R.Karl Dieter、Lois E. Nice、Sadanandan E. Velu
DOI:10.1016/0040-4039(96)00295-x
日期:1996.4
Mixtures of oxone and sodium chloride or sodium bromide afford solutions of chlorine or bromine, respectively. These solutions effectively add chlorine and bromine to α,β-enones and alkenes. The method affords improved yields of 3-alkyl-2-halo-2-cycloalkenones which are sometimes difficult to prepare.
Favorskii-Type Rearrangement of α,α′-Dihalo Ketones Induced by Enolates of (Diethoxyphosphinyl)acetic Esters and Its Application to the Synthesis of α,α′-Divinyl Ketones
A Favorskii-type rearrangement of 1,3-dihalo-3-methyl-2-butanone with enolate of ethyl (diethoxyphosphinyl)acetate or t-butyl (diethoxyphosphinyl)acetate gave ethyl 2-(diethoxyphosphinyl)-5-methyl-3-oxo-4-hexenoate (3a) or its t-butyl ester (3b). Compound 3b was applied to the preparation of (E)-5-methyl-1-(p-tolyl)-1,4-hexadien-3-one and diethyl (4-methyl-2-oxo-3-pentenyl)phosphonate, which are the important intermediates for natural product syntheses.
The highly diastereoselective alleneformation by photosensitized oxygenation of the significantly twisted novel 1,3-dienes which possess an sp3 chiral center due to a secondary hydroxy group and a tertiary alkoxy group at allylic positions is described.
Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCl (HBr) Acetonitrile Reagent
作者:Lilian Kao Liu、Ching-Shan Lin
DOI:10.1002/jccs.199600010
日期:1996.2
AbstractAddition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25‐60 °C) with excellent to moderate yields.