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首页> 外文期刊>Chemistry: A European journal >Intermolecular Alkene and Alkyne Hydroacylation with beta-S-Substituted Aldehydes: Mechanistic Insight into the Role of a Hemilabile P-O-P Ligand
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Intermolecular Alkene and Alkyne Hydroacylation with beta-S-Substituted Aldehydes: Mechanistic Insight into the Role of a Hemilabile P-O-P Ligand

机译：分子间的烯烃和炔烃与β-S取代的醛加氢酰化：机械视角的半不稳定的P-O-P配体的作用。

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摘要

A straightforward to assemble catalytic system for the intermolecular hydroacylation reaction of beta-S-substituted aldehydes with activated and unactivated alkenes and alkynes is reported. These catalysts promote the hydroacylation reaction between beta-S-substituted aldehydes and challenging substrates, such as internal alkynes and I-octene. The catalysts are based upon [Rh(cod)(DPEphos)][ClO4] (DPE-phos= bis(2-diphenylphosphinophenyl)-ether, cod=cyclooctadiene) and were designed to make use of the hemilabile capabilities of the DPEphos ligand to stabilise key acyl-hydrido intermediates against reductive decarbonylation, which results in catalyst death. Studies on the stoichiometric addition of aldehyde (either ortho-HCOCH2CH2SMe or ortho-HCOC6H4SMe) and methylacrylate to precursor acetone complexes [Rh(acetone)2(DPEphos)][X] [X=closo-CB11H6Cl6 or [BAr4F] (Ar-F = 3,5-(CF3)(2)C6H3)] reveal the role of the hemilabile DPEphos ligand. The crystal structure of [Rh(acetone)(2)- (DPEphos)][X] shows a cis-coordinated diphosphine ligand with the oxygen atom of the DPEphos distal from the rhodium. Addition of aldehyde forms the acyl hydride complexes [Rh(DPEphos)(COCH2CH2SMe)H][X] or [Rh(DPEphos)(COC6H4SMe)H][X], which have a trans-spanning DPEphos ligand and a coordinated ether group. Compared to analogous complexes prepared with dppe (dppe=1,2-bis(diphenylphosphino)ethane), these DPEphos complexes show significantly increased resistance towards reductive decarbonylation. The crystal structure of the reductive decarbonylation product [Rh(CO)(DPEphos)(EtSMe)][closo-CB11H6I6] is reported. Addition of alkene (methylacrylate) to the acyl-hydrido complexes forms the final complexes [Rh(DPEphos)(eta(1)-MeSC2H4-eta(1)-COC2H4CO2Me)][X] and [Rh(DPEphos)(eta(1)-MeSC6H4-eta(1)-COC2H4- CO2Me)][X], which have been identified spectroscopically and by ESIMS/MS. Intermediate species in this transformation have been observed and tentatively characterised as the alkyl-acyl complexes [Rh(CH2CH2CO2Me)-(COC2H4SMe)(DPEphos][X] and [Rh(CH2CH2CO2Me)(COC6H4SMe)-(DPEphos)][X]. In these complexes, the DPEphos ligand is now cis chelating. A model for the (unobserved) transient alkene complex that would result from addition of alkene to the acyl-hydrido complexes comes from formation of the MeCN adducts [Rh(DPEphos)(MeSC2H4CO)H(MeCN)] [X] and [Rh(DPEphos)(MeSC6- H4CO)H(MeCN)][X]. Changing the ligand from DPEphos to one with a CH2 linkage, [Ph2P(C6H4)](2)CH2, gave only decomposition on addition of aldehyde to the acetone precursor, which demonstrated the importance of the hemiabile ether group in DPEphos. With [Ph2P(C6H4)](2)S, the sulfur atom has the opposite effect and binds too strongly to the metal centre to allow access to productive acetone intermediates.
机译：报道了一种用于组装β-S-取代的醛与活化的和未活化的烯烃和炔烃的分子间氢酰化反应的直接组装的催化体系。这些催化剂促进了β-S-取代的醛与具有挑战性的底物（例如内部炔烃和1-辛烯）之间的加氢酰化反应。催化剂基于[Rh（cod）（DPEphos）] [ClO4]（DPE-phos =双（2-二苯基膦基苯基）-醚，cod =环辛二烯），并设计为利用DPEphos配体的半挥发性稳定关键的酰基氢化物中间体以防止还原性脱羰作用，从而导致催化剂死亡。将醛（邻-HCOCH2CH2SMe或邻-HCOC6H4SMe）和丙烯酸甲酯化学计量添加至丙酮前体[Rh（丙酮）2（DPEphos）] [X] [X = closo-CB11H6Cl6或[BAr4F]（Ar-F = 3,5-（CF3）（2）C6H3）]揭示了半不稳定DPEphos配体的作用。 [Rh（丙酮）（2）-（DPEphos）] [X]的晶体结构显示顺式配位的二膦配体，DPEphos的氧原子位于铑的远端。醛的添加形成酰基氢化物配合物[Rh（DPEphos）（COCH2CH2SMe）H] [X]或[Rh（DPEphos）（COC6H4SMe）H] [X]，其具有跨跨的DPEphos配体和配位的醚基。与用dppe（dppe = 1,2-双（二苯基膦基）乙烷）制备的类似络合物相比，这些DPEphos络合物对还原性脱羰基的抵抗力显着提高。报告了还原性脱羰基产物[Rh（CO）（DPEphos）（EtSMe）] [closo-CB11H6I6]的晶体结构。将烯烃（丙烯酸甲酯）加到酰基-氢化物络合物上形成最终络合物[Rh（DPEphos）（eta（1）-MeSC2H4-eta（1）-COC2H4CO2Me）] [X]和[Rh（DPEphos）（eta（1） ）-MeSC6H4-eta（1）-COC2H4- CO2Me）] [X]，已通过光谱法和ESIMS / MS进行了鉴定。已观察到该转化中的中间物种，并初步表征为烷基-酰基配合物[Rh（CH2CH2CO2Me）-（COC2H4SMe）（DPEphos] [X]和[Rh（CH2CH2CO2Me）（COC6H4SMe）-（DPEphos）] [X]。在这些络合物中，DPEphos配体现在是顺式螯合的，由于将烯烃添加到酰基-氢化物络合物中而形成的（未观察到的）瞬态烯烃络合物的模型来自于MeCN加合物的形成[Rh（DPEphos）（MeSC2H4CO） H（MeCN）] [X]和[Rh（DPEphos）（MeSC6- H4CO）H（MeCN）] [X]。将配体从DPEphos更改为带有CH2键的配体[Ph2P（C6H4）]（2）CH2 ，仅在醛加到丙酮前体上时分解，这证明了DPEphos中半可醚基的重要性。与[Ph2P（C6H4）]（2）S相比，硫原子具有相反的作用，并且与DPEphos的结合太强金属中心，以获取生产性丙酮中间体。

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