多齿胺膦钌配合物催化苯乙酮的氢转移氢化

利用Ｃ２－对称的双胺双膦钌（Ⅱ）配合物ＲｕＣｌ２（Ｐ２Ｎ２Ｈ４）为催化剂，研究了苯乙酮的氢转移还原反应。在苯乙酮、钌配合物和异丙氧基钾的摩尔比为２００：１：１２的条件下，于６５℃反应２ｈ后，苯乙酮的转化率高达９９％。讨论了苯乙酮的氢转移氢化机理。     

新的双胺双膦钌配合物的合成、表征和催化性能

Polydentate ligands, N,N'-bis[o-(diphenylphosphino)benzylidene]-1,2-propane-diamine [P2N2Me for short] and N,N'-bis[o-(diphenylphosphino)benzy1]-1,2-propanediamine [P2N2 H4Me for short] have been synthesized. The interaction of RuCl2(DMSO)4 with one equivalent of P2N2Me or P2N2H4Me in refluxing toluene gave trans-RuCl2(P2N2Me) and trans-RuCl2(P2N4H4Me) in good yield, respectively. The ligands and the complexes have been fully characterized by elemental analysis and spectroscopic methods. The complexes act as an excellent catalyst precursor in hydrogen transfer hydrogenation of acetophenone in catalyst: acetophenone :iso-PrOK of 1: 100: 15, leading to 2-phenylethanol of 89-96% yield.     

手性多齿胺膦钌配合物的设计合成和在芳香酮不对称氢化反应中的应用

简要介绍了多齿胺膦金属配合物的设计合成。这些多齿配合显示了单齿胺或膦金属配合物所不具有的丰富结构类型和特殊催化性质，合成和表征了含有结构类似的双亚胺双膦钌配合物（Ｒ，Ｒ）－３和双胺双膦钌配合物（Ｒ，Ｒ）－４。配合物（Ｒ，Ｒ）－４可作为多种芳香酮不对称氢化的手性催化剂，其光学收率最高达９７％。讨论了钌配合物的催化作用机理。     

钌氢配合物的合成及其在催化有机合成中的应用

配位催化己成实现绿色化学中的重要手段之一[1,2].过渡金属配合物是重要的配位催化剂,但中心金属多为贵金属,其中钌的儲量较大,也较便宜.不过,钌配合物的催化性能也较差.在国内外学者的努力下,近年在钌配合物的合成和催化方面都得到很大发展[3],如钌卡宾[C l2Ru(=CHPh)(PCy3)2]催化的交互置换反应获2005年Nobel化学奖[4].过渡金属氢配合物是一类重要的配合物,被称为“催化反应的关键”[5].如铱氢配合物首开了活化饱和碳氢键的先河,铼氢配合物实现了饱和碳氢键催化循环[6];钌氢配合物在催化加氢等反应中也表现不俗[7].我们试图对钌氢配合…     

亚胺膦钌配合物RuCl2P2N2的合成和催化性能

ＲｕＣｌ２（Ｐｈ３Ｐ）４或ＲｕＣｌ２（ＤＭＳＯ）４在甲苯中直接与等摩尔的亚胺膦配体Ｎ，Ｎ－双－［邻－（二苯基膦苯亚甲基）］乙二胺（Ｐ２Ｎ２）在甲苯中回流反应，高产率地合成了反式配位的双亚胺双膦钌配合物ｔｒａｎｓ－ＲｕＣｌ２Ｐ２Ｎ２．在温和条件下，该配合物作为新型催化剂有效地催化α，β－不饱和酸和几种功能团烯烃的选择加氢反应．讨论了可能的催化活性物种．     

胺基膦钌卡宾化合物的合成及催化烯烃复分解反应

合成并表征了一类含新型胺基膦配体的Grubbs二代型钌卡宾烯烃复分解催化剂[RuCl₂(H₂IMes)·(R¹HNPR²₂)(=CHPh)], 采用核磁共振波谱和单晶X射线衍射确定了催化剂的结构. 在室温条件下, 以N,N-二烯丙基-对甲苯磺酰胺的关环复分解反应(RCM)为模型, 考察了不同胺基膦配体对钌卡宾催化反应速率的影响. 结果表明, G2?1表现出最佳的催化活性. 通过底物研究发现, G2?1催化剂(摩尔分数, 1%)对双端烯及多端烯的RCM反应具有较好的活性和官能团适应性, 产物收率均>95%; G2?1催化剂同样适用于同(异)端烯底物的交叉复分解反应(CM), 其催化苯乙烯与3-苯氧基丙烯的CM反应时产物收率高达92%.     

钌分子氢配合物催化烯烃的离子氢化

在氢气压力下，钌配合物[^MeCnRuCl(dppe)](O3SCF3)与AgO3SC3在CH2Cl2中反应生成分子氢配合物[^MeCnRu(H2)(dppe)](O3SCF3)2，该分子氢配合物具有催化烯烃离子氢化的活性。原位高压核磁共振研究显示，这种催化离子氢化反应可能是由分子氢配合物向烯烃转移氢质子形成碳正离子引起的。     

光学活性胺膦配体的合成与在不对称催化中的应用

用邻二苯基膦苯甲醛与不同的手性二胺缩合,高产率地制备了一系列手性双胺双膦配体。这些配体分别与Ru(DMSO)4Cl2或[Rh(COD)Cl]2等反应,可制备相应的手性双胺双膦钌、铑配合物。在异丙醇溶液中,该C2-对称的手性双胺双膦钌、铑配合物是多种芳香酮不对称转移氢化的优化催化剂,反应产物手性芳香醇的转华裔经和对映选择性分别高达99%和98ee。     

三烷基膦—铂—氢配合物的合成及NMR研究

合成了配合物ｔｒａｎｓ－ＰｔＨＸＬ２（Ｌ＝ＰＢｕ３，ＰＰｒ３，ＰＥｔ３；Ｘ＝Ｃｌ＾－，Ｂｒ＾－，Ｉ＾－，ＮＯ＾－３，ＮＯ＾－２，ＳＣＮ＾－，ＣＮ＾－），并进行了ＨＮＭＲ研究。测得Ｐｔ－Ｈ键的Ｈ的高场的化学位移δ＝－８～－２４ｐｐｍ；Ｊ＝８００～１５００Ｈｚ和Ｊｐ－Ｈ＝１３．０～１７．０Ｈｚ，鉴定了配合物的顺反异构和键合异构。研究了阴离子配体（Ｘ）及中性配体（Ｌ）对Ｐｔ－Ｈ键的δ的关系，Ｐｔ－Ｈ化学     

Highly Efficient Transfer Hydrogenation Catalysis with Tailored Pyridylidene Amide Pincer Ruthenium Complexes

The rational optimization of homogeneous catalysts requires ligand platforms that are easily tailored to improve catalytic performance. Here, it is demonstrated that pyridylidene amides (PYAs) provide such a platform to custom-shape transfer hydrogenation catalysts with exceptional activity. Specifically, a series of meta-PYA pincer ligands with differently substituted PYA units has been synthezised and coordinated to ruthenium(II) centres to form bench-stable tris-acetonitrile complexes [Ru(R-PYA-pincer)(MeCN)₃](PF₆)₂ (R=OMe, Me, H, Cl, CF₃). Analytic studies including ¹H NMR spectroscopy, cyclic voltammetry, and X-ray crystallography reveal a direct influence of the substituents on the electronic properties of the ruthenium center. The complexes are active in the catalytic transfer hydrogenation of ketones, with activities directly encoded by the PYA substitution pattern. Their perfomance improves further upon exchange of an ancillary MeCN ligand with PPh₃. While complexes [Ru(R-PYA-pincer)(PPh₃)(MeCN)₂](PF₆)₂ were only isolated for R=H, Me, an in situ protocol was developed to generate these complexes in situ for R=OMe, Cl, CF₃ by using a 1:2 ratio of the complexes and PPh₃. This in situ protocol together with a short catalyst pre-activation provided highly active catalytic systems. The most active pre-catalyst featured the methoxy-substituted PYA ligand and reached turnover frenquencies of 210 000 h⁻¹ under an exceptionally low catalyst loading of 25 ppm for the benchmark substrate benzophenone, representing one of the most active transfer hydrogenation systems known to date.     

芳香酮的高效对映选择性转移氢化

手性芳香醇在制药工业上有重要的应用,因而利用芳香酮的对映选择性氢化制备相应的手性醇已引起人们极大关注.近10年来,用手性金属配合物为催化剂,利用种种有机物作氢源,实现芳香酮的不对称氢转移氢化取得了很大进展.但这些反应过程的催化活性仍然较低,底物酮与催化剂.     

CNN Pincer Ruthenium Catalysts for Hydrogenation and Transfer Hydrogenation of Ketones: Experimental and Computational Studies

Reaction of [RuCl(CNN)(dppb)] ( 1‐Cl ) (HCNN=2‐aminomethyl‐6‐(4‐methylphenyl)pyridine; dppb=Ph₂P(CH₂)₄PPh₂) with NaOCH₂CF₃ leads to the amine‐alkoxide [Ru(CNN)(OCH₂CF₃)(dppb)] ( 1‐OCH₂CF₃ ), whose neutron diffraction study reveals a short RuO ??? HN bond length. Treatment of 1‐Cl with NaOEt and EtOH affords the alkoxide [Ru(CNN)(OEt)(dppb)] ? (EtOH)_n ( 1‐OEt?n EtOH ), which equilibrates with the hydride [RuH(CNN)(dppb)] ( 1‐H ) and acetaldehyde. Compound 1‐OEt?n EtOH reacts reversibly with H₂ leading to 1‐H and EtOH through dihydrogen splitting. NMR spectroscopic studies on 1‐OEt?n EtOH and 1‐H reveal hydrogen bond interactions and exchange processes. The chloride 1‐Cl catalyzes the hydrogenation (5 atm of H₂) of ketones to alcohols (turnover frequency (TOF) up to 6.5×10⁴ h^?1, 40 °C). DFT calculations were performed on the reaction of [RuH(CNN′)(dmpb)] ( 2‐H ) (HCNN′=2‐aminomethyl‐6‐(phenyl)pyridine; dmpb=Me₂P(CH₂)₄PMe₂) with acetone and with one molecule of 2‐propanol, in alcohol, with the alkoxide complex being the most stable species. In the first step, the Ru‐hydride transfers one hydrogen atom to the carbon of the ketone, whereas the second hydrogen transfer from NH₂ is mediated by the alcohol and leads to the key “amide” intermediate. Regeneration of the hydride complex may occur by reaction with 2‐propanol or with H₂; both pathways have low barriers and are alcohol assisted.     

Ruthenium(II) Tris-Pyrazolylmethane Complexes in Transfer Hydrogenation Reactions

While ruthenium(II) arene complexes have been widely investigated for their potential in catalytic transfer hydrogenation, studies on homologous compounds replacing the arene ligand with the six-electron donor tris(1-pyrazolyl)methane (tpm) are almost absent in the literature. The reactions of [RuCl(κ³-tpm)(PPh₃)₂]Cl, 1 , with a series of nitrogen ligands (L) proceeded with selective PPh₃ mono-substitution, affording the novel complexes [RuCl(κ³-tpm)(PPh₃)(L)]Cl (L=NCMe, 2 ; NCPh, 3 ; imidazole, 4 ) in almost quantitative yields. Products 2 – 4 were fully characterized by IR and multinuclear NMR spectroscopy, moreover the molecular structure of 4 was ascertained by single crystal X-ray diffraction. Compounds 2 – 4 were evaluated as catalytic precursors in the transfer hydrogenation of a series of ketones with isopropanol as the hydrogen source, and 2 exhibited the highest activity. Extensive NMR experiments and DFT calculations allowed to elucidate the mechanism of the transfer hydrogenation process, suggesting the crucial role played by the tpm ligand, reversibly switching from tri- to bidentate coordination during the catalytic cycle.     

水/有机两相体系中钌膦配合物催化苯乙酮及其衍生物的不对称加氢反应

 将手性二胺(1S,2S)-1,2-二苯基乙二胺二磺酸钠((1S,2S)-DPENDS)修饰的钌膦配合物用于催化水/有机两相体系中苯乙酮的不对称加氢. 结果表明, (1S,2S)-DPENDS和KOH的浓度对反应有很大影响,二者的协同作用使配合物的催化活性和产物的对映选择性大大提高. 对温度、压力、底物/钌的摩尔比和膦配体/钌摩尔比等反应条件进行优化后,以［RuCl2-(TPPTS)2］2为催化剂前体催化苯乙酮不对称加氢时,产物的ee值可达66.4%, 催化剂经过简单的相分离即可循环使用.     

Terpyridine Diphosphine Ruthenium Complexes as Efficient Photocatalysts for the Transfer Hydrogenation of Carbonyl Compounds

The cationic achiral and chiral terpyridine diphosphine ruthenium complexes [RuCl(PP)(tpy)]Cl (PP=dppp ( 1 ), (R,R)-Skewphos ( 2 ) and (S,S)-Skewphos ( 3 )) are easily obtained in 85–88 % yield through a one-pot synthesis from [RuCl₂(PPh₃)₃], the diphosphine and 2,2′:6′,2′′-terpyridine (tpy) in 1-butanol. Treatment of 1 – 3 with NaPF₆ in methanol at RT affords quantitatively the corresponding derivatives [RuCl(PP)(tpy)]PF₆ (PP=dppp ( 1 a ), (R,R)-Skewphos ( 2 a ) and (S,S)-Skewphos ( 3 a )). Reaction of [RuCl₂(PPh₃)₃] with (S,R)-Josiphos or (R)-BINAP in toluene, followed by treatment with tpy in 1-butanol and finally with NaPF₆ in MeOH gives [RuCl(PP)(tpy)]PF₆ (PP=(S,R)-Josiphos ( 4 a ), (R)-BINAP ( 5 a )) isolated in 78 % and 86 % yield, respectively. The chiral derivatives have been isolated as single stereoisomers and 3 a , 4 a have been characterized by single crystal X-ray diffraction studies. The tpy complexes with NaOiPr display high photocatalytic activity in the transfer hydrogenation (TH) of carbonyl compounds using 2-propanol as the only hydrogen donor and visible light at 30 °C, at remarkably high S/C (up to 5000) and TOF values up to 264 h⁻¹. The chiral enantiomers 2 , 2 a and 3 , 3 a induce the asymmetric photocatalytic TH of acetophenone, affording (S)- and (R)-1-phenylethanol with 51 and 52 % ee, respectively, in a MeOH/2-propanol mixture.     

Novel Chiral PNNP-Ru Complexes:Synthesis and Application in Asymmetric Transfer Hydrogenation of Ketones

The efficient catalytic systems generated in situ from RuCl2(PPh3)3 and chiral ligands N,N-bis[2-(di-o- tolylphosphino)-benzyl]cyclohexane-1,2-diamine(2) were employed for asymmetric transfer hydrogenation of aromatic ketones, giving the corresponding optically active alcohols with high activities(up to 99% conversion) and excellent enantioselectivities(up to 96% e.e.) under mild conditions. The chiral ruthenium(Ⅱ) complex (R,R)-3 has been prepared and characterized by NMR and X-ray crystallography.