Selective Propargylation of Carbonyl Compounds and Imines with Barium Reagents

A Barbier‐type regioselective propargylation of aldehydes and ketones with (3‐bromobut‐1‐ynyl)trimethylsilane has been achieved using reactive barium as a low‐valent metal in THF. Especially in the case of ketones, the corresponding homopropargylic alcohols form almost exclusively. In the reaction of α,β‐unsaturated carbonyl compounds, only 1,2‐adducts have been observed. This method is also applicable to propargylation of imines, and the corresponding homopropargylic amines are obtained regiospecifically in good yields with diastereomeric ratios of up to 87:13.     

Chalcogeno-Morita-Baylis-Hillman Reaction of Chalcogenide-Enones with Carbonyl Compounds

Abstract

The Chalcogeno-Morita-Baylis-Hillman reaction was achieved by the reactions of 2-(methylchalcogeno)phenyl vinyl ketones with carbonyl compounds or acetals in the presence of BF₃· Et₂O. This reaction proceeds via the intramolecular Michael addition of the chalcogenide group to an enone moiety followed by the aldol reaction of the resulting chalcogenonio-enolate with an aldehyde. The reactions were worked up with triethylamine or saturated aqueous NaHCO₃ to give the α -methylene aldols (the Morita-Baylis-Hillman adducts).     

Solvation Effects in the Grignard Reaction with Carbonyl Compounds

Ratios of the yields of addition and reduction products for the reactions of butylmagnesium chloride with diisopropyl ketone, methyl 2‐methylpropanoate, and isopropyl 2‐methylpropanoate in toluene were determined at different THF, diethyl ether, and tert‐butyl methyl ether contents in the Grignard reagent. Replacement of the alkoxy group in the ester leads to strikingly different results for very small additions of donors. The results are discussed in terms of the solvation of the species in the reaction mixture.     

O-芳基苯基硫代膦酰肼与某些羧基化合物的反应

为探索 O-芳基苯基硫代膦酰肼的反应性能、测试所得产物的生物活性,寻找活性结构,本文研究了它与几种羰基化合物α-(1,2,4 三唑基)片呐酮、邻苯二甲酰氯,反式菊酰氯和原甲酸三乙酯的反应,合成了21个新的     

The Forgotten Carbonyl Reaction: Chloroacetylation and Bromoacetylation of Carbonyl Compounds

Halomethyl acetates ( 3 ) could be prepared from aliphatic, α,β‐unsaturated and aromatic aldehydes, as well as from alicyclic ketones with high yields in simple one‐pot reactions. Very often, the products didn't have to be purified and could directly be used for synthetic purposes after evaporation of the solvent. Obviously, the ‘bad reputation’ of the reaction in the literature stemed from the fact that the reactions didn't take place under the best conditions. Carbonyl compounds ( 1 ) and acyl halides ( 2 ) form equilibria which are completely on the side of the halomethyl acetates ( 3 ) at room temperature (starting with aliphatic and most aromatic aldehydes) and which can be strongly influenced by the reaction parameters. It is crucial to work at low temperature in apolar solvents and to remove (or deactivate) the catalyst before workup. Reactions may be realized with or without solvents. Side reactions were observed with formaldehyde and acetaldehyde but, with exception of formaldehyde, could be reduced close to zero (see Fig. 5). By‐products were essentially avoided if the reaction took place in apolar solvents and with a local excess of acetyl chloride. In many cases clean products were available which could directly be used for synthetic purposes. Halomethyl acetates ( 3 ) are bifunctional carbonyl derivatives with two different leaving groups, whose preparative advantages have been useful for the synthesis of various pentafulvenes, but were especially important for preparing unstable parent fulvenes and fulvalenes.     

The Reaction of Phosphonyl Radicals with Hindered Carbonyl Compounds

Abstract

The reaction between phosphonyl radicals and substituted o-and p-benzoquinone has been studied by ESR. The addition of phosphonyl radicals to benzoquinone occurs at two sites, either at carbonyl oxygen or at double bond of the cycle. The reaction of phosphonyl radicals with p-benzoquinone and methylenquinones proceeds in a similar fashion.     

羰基钴及其盐的合成方法研究进展

详细评述了羰基钴及其盐的合成方法。参考文献４５篇。     

Microwave-Assisted Acetalization of Carbonyl Compounds Catalyzed by Reusable Envirocat® Supported Reagents

Envirocat® supported reagents (EPZG, EPZ10, and EPIC) are found to efficiently catalyze the acetalization of carbonyl compounds with 1,2-ethanediol under microwave irradiation under solvent-free conditions. The reagents can be used in repeated experiments to perform the reaction with the same activity.     

水相中锌促进的羰基化合物频哪醇偶联反应实验设计

介绍水相中锌促进的羰基化合物频哪醇偶联反应的实验设计。通过苯甲醛频哪醇偶联反应得到相应的1,2-二苯基．1,2-乙二醇,学习水相有机反应和微量反应的基本操作,加强基础研究、绿色化学与有机化学实验之间的紧密联系。     

The Reaction of some Carbonyl and Thiocarbonyl Compounds with Prenyl- and Crotyllithium in Tetrahydrofuran Solution

Prenyllithium (3-methylbut-2-enyl-lithium) ( 1 ) and cis-crotyllithium (Z-but-2-enyl-lithium) ( 2 ) in tetrahydrofuran solution, prepared according to the method of Eisch & Jacobs, react with carbonyl compounds to give the branched alcoholates with moderate to high selectivity, unless access to the carbonyl group is strongly hindered (see the Table). Adamantanethione ( 12 ) reacts with 1 to give the unbranched thiolate.     

Organotitanium carbonyls. Reaction of tetrabenzyl-titanium with carbon monoxide

Tetrabenzyltitanium and its dicyclohexylamine adduct react with carbon monoxide to form acylbenzyltitanium compounds, which have been characterized. The presence of (PhCH₂)₄Ti(CO)₂ (amine) and (PhCH₂)₄Ti(CO) (amine) as intermediates was indicated by the IR spectra.     

金属锌促进羰基化合物水相嚬呐偶合反应

报道了一种简便、有效的水相噤呐偶合反应。在含有少量季铵盐或季磷盐的氯化铵水溶液中．用金属锌促进羰基化合物进行水相噘呐偶合反应，其中加入的少量季铵盐或季磷盐有助于显著提高反应产率，噘呐醇产率由53％提高到87％。但噘呐偶合反应的产率受羰基周围环境的立体位阻影响较大，在此条件下，金属锌可有效地促进芳香族醛化合物进行水相噘呐偶合反应，得到产率较高的噘呐醇，但非对映异构体选择性差，而脂肪族醛化合物得到的噘呐醇产率较低，在同样条件下，酮类化合物不能顺利进行噘呐偶合反应。     

金属锌促进羰基化合物水相嚬呐偶合反应

报道了一种简便、有效的水相嚬呐偶合反应。在含有少量季铵盐或季磷盐的氯化铵水溶液中,用金属锌促进羰基化合物进行水相嚬呐偶合反应,其中加入的少量季铵盐或季磷盐有助于显著提高反应产率,嚬呐醇产率由53%提高到87%。但嚬呐偶合反应的产率受羰基周围环境的立体位阻影响较大,在此条件下,金属锌可有效地促进芳香族醛化合物进行水相嚬呐偶合反应,得到产率较高的嚬呐醇,但非对映异构体选择性差,而脂肪族醛化合物得到的嚬呐醇产率较低,在同样条件下,酮类化合物不能顺利进行嚬呐偶合反应。     

羰基化合物及其与卤代烃在CeCl_3/萘锂试剂作用下的反应

用萘锂(LiNp)还原无水CeCl_3制得的活性金属铈(Ce~*)在与羰基化合物的反应中,与用相同方法制得的Nd~*相比,表现出更高的反应活性。Ce~*与羰基化合物反应经水解可生成相应的醇,频哪醇和烯烃,其选择性不仅与反应时间和温度有关,而且还与羰基化合物的种类以及CeCl_3:LiNp:RCOR＇的摩尔比有关。初步研究了Ce~*作用下的酮和一些卤代烃的反应。     

羰基化合物还原偶联为频呐醇反应的研究新进展

综述了近几年来羰基化合物还原偶联为频呐醇反应的研究新进展．     

全氟辛基磺酸茂锆催化吲哚与羰基化合物反应

在1.0 mol%二(全氟辛基磺酸)二茂锆存在下,吲哚与醛、酮在室温、四氢呋喃中反应10～25 min,生成二吲哚甲烷衍生物,收率达86%～96%.催化剂二(全氟辛基磺酸)二茂锆能重复使用6次,转化率仍有90%;反应不需要在严格的无水条件下进行,上述过程为二吲哚甲烷衍生物制备提供一条新的有效途径.