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首页> 外文期刊>Chemistry: A European journal >Oxorhenium Complexes as Aldehyde-Olefination Catalysts
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Oxorhenium Complexes as Aldehyde-Olefination Catalysts

机译：氧化or络合物作为醛加氢催化剂

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Several oxorhenium com-pounds in the formal oxidation states v and VII are examined as catalysts for the aldehyde-olefination starting from diazo compounds,phosphines,and aldehydes.Of these,[ReMeO_2(eta~2-alkyne)] complexes provide the simplest catalysts to study,although [Re-OCl_3CPPh_3]_2] still remains the most efficient rhenium catalyst for aldehyde-olefination described to date.Prior to the reaction with the Re catalysts the phosphine and the diazo compound react to form a phosphazine.No catalytic reaction occurs in cases where no phosphazine formation is observed.The first step of the catalytic cycle involves the formation of a carbene intermediate by the reaction of phosphazine and catalyst under extrusion of phosphine oxide and dinitrogen.In a second step the carbene reacts with aldehyde under olefin formation and catalyst regeneration.Excess of alkyne as well as the presence of ketones slows Several oxorhenium com-pounds in the formal oxidation states v and VII are examined as catalysts for the aldehyde-olefination starting from diazo compounds,phosphines,and aldehydes.Of these,[ReMeO_2(eta~2-alkyne)] complexes provide the simplest catalysts to study,although [Re-OCl_3CPPh_3]_2] still remains the most efficient rhenium catalyst for aldehyde-olefination described to date.Prior to the reaction with the Re catalysts the phosphine and the diazo compound react to form a phosphazine.No catalytic reaction occurs in cases where no phosphazine formation is observed.The first step of the catalytic cycle involves the formation of a carbene intermediate by the reaction of phosphazine and catalyst under extrusion of phosphine oxide and dinitrogen.In a second step the carbene reacts with aldehyde under olefin formation and catalyst regeneration.Excess of alkyne as well as the presence of ketones slows down the catalytic reaction.The olefi-nation of 4-nitrobenzaldehyde with di-azomalonate is possible with these Re catalysts.In contrast,this reaction does not take place either in the classical Wittig fashion from PH_3P=C(CO_2Et)_2 and aldehyde or by use of all other catalysts for aldehyde olefination reactions reported to date.Catalytic ylide formation from diazo compounds seems therefore not to be the only pathway through which catalytic aldehyde-olefination reactions can proceed.
机译：以重氮化合物，膦和醛为原料，考察了几种形式氧化态v和VII的氧or化合物作为醛-烯化反应的催化剂。其中，[ReMeO_2（eta〜2-炔）]配合物提供了最简单的催化剂进行研究，尽管[Re-OCl_3CPPh_3] _2]仍然是迄今为止描述的最有效的醛-烯化ation催化剂。在与Re催化剂反应之前，膦和重氮化合物反应生成膦嗪。没有催化反应发生在未观察到膦嗪形成的情况下，催化循环的第一步包括在氧化膦和二氮的挤压下，膦嗪与催化剂反应形成卡宾中间体。第二步，在烯烃形成下卡宾与醛反应炔烃的过量以及酮的存在会减慢几种形式为v和VII的氧化态的氧as化合物从重氮化合物，膦和醛开始的用于醛-烯化的催化剂迄今为止已描述的用于醛-烯烃化的催化剂。在与Re催化剂反应之前，膦和重氮化合物反应形成膦嗪。在未观察到膦嗪形成的情况下，不会发生催化反应。催化循环的第一步涉及在氧化膦和二氮的挤压下通过膦嗪和催化剂的反应形成卡宾中间体。在第二步中，在烯烃形成和催化剂再生下卡宾与醛反应。炔烃的过量以及酮的存在减慢了速度这些Re催化剂可将4-硝基苯甲醛与重氮丙二酸二甲酯进行烯烃化反应。相反，该反应不会发生迄今已有报道以经典的维蒂希方式从PH_3P = C（CO_2Et）_2和醛或使用所有其他催化剂进行醛烯化反应。因此，重氮化合物催化生成内鎓盐似乎并不是催化醛-可以进行烯化反应。

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