NHC-catalyzed C–O or C–N bond formation: efficient approaches to α,β-unsaturated esters and amides
作者:Bo Zhang、Peng Feng、Yuxin Cui、Ning Jiao
DOI:10.1039/c2cc32862c
日期:——
Simple and efficient NHC-catalyzed transformations of bromoenal or α,β-dibromoenal into α,β-unsaturated esters or amides with high stereoselectivity through CâO or CâN bond formation have been demonstrated. The NHC-catalyzed processes occur under mild conditions. The ready availability of the starting materials, avoidance of external oxidants and the usefulness of the products all make the strategy attractive.
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.
Carbenes ring true: N‐Heterocycliccarbene (NHC) catalyzed reactions of α‐bromo‐α,β‐unsaturated aldehydes/α,β‐dibromoaldehydes with 1,3‐dinucleophilic reagents, such as 1,3‐dicarbonyl compounds, β‐enamino ketones, and β‐enamino esters through umpolung processes gave functionalized 3,4‐dihydropyranones and 3,4‐dihydropyridinones (see scheme). The availability of the starting materials, lack of external
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.
Experimental and Theoretical Study of an Intramolecular CF<sub>3</sub>-Group Shift in the Reactions of α-Bromoenones with 1,2-Diamines
作者:Vasily M. Muzalevskiy、Yury A. Ustynyuk、Igor P. Gloriozov、Vyacheslav A. Chertkov、Alexander Yu. Rulev、Evgeniy V. Kondrashov、Igor A. Ushakov、Alexey R. Romanov、Valentine G. Nenajdenko
DOI:10.1002/chem.201502706
日期:2015.11.16
The reactions of trifluoromethylated 2‐bromoenones and N,N′‐dialkyl‐1,2‐diamines have been studied. Depending on the structures of the starting compounds, the formation of 2‐trifluoroacetylpiperazine or 3‐trifluoromethylpiperazine‐2‐ones was observed. The mechanism of the reaction is discussed in terms of multistep processes involving sequential substitution of bromine in the starting α‐bromoenones