氮杂环卡宾的合成及在氢转移反应中的应用

利用氯甲基吡啶与咪唑反应制备了一系列含吡啶取代咪唑L1～L5,考察了所得咪唑衍生物与钌化合物在碱性条件下原位形成的氮杂卡宾钌络合物对苯胺与醇氢转移反应的催化活性.研究了碱的种类、钌前体、温度等对反应的影响,结果表明RuCl3 H2O/1-(2-吡啶甲基)-3-甲基碘化咪唑(L3)/KOH催化体系在185℃时对苯胺与乙二醇反应的催化活性较高,选择性生成N-羟乙基苯胺,TON(单位活性转化的底物分数)可达2130.此外,还考察了RuCl3 H2O/L3/KOH催化体系对苯胺与丁醇、环己醇、异丙醇、苯甲醇反应的催化性能.在催化剂作用下,醇与苯胺可形成亚胺及仲胺,伯醇可以自氢转移反应形成酯,反应产物的结构及选择性取决于醇的结构及反应条件.     

手性氨基酸及其衍生物配体在酮不对称氢转移反应中的应用进展

前手性酮的不对称氢转移反应(ATH)是获得手性醇的重要方法.近年来氨基酸及其衍生物在金属Ru,Rh,Ir催化酮的ATH中的应用引起人们关注.就氨基酸、氨基酸酰胺、氨基酸硫代酰胺、氨基酸羟胺酸、氨基酸酰肼、氨基醇及氨基酸羟基酰胺等为配体的金属络合物在ATH中的催化性能进行了综述.     

新型N-P配体的合成、表征及其在氢转移反应中的应用

利用2,3-二(二苯膦氧基)-1,3-丁二烯与胺的迈克尔加成反应,合成了单胺基及环胺基改性的有机氧化膦,经有机硅烷还原,制备出胺基取代的膦配体,所得化合物经NMR及单晶X射线衍射分析.考察了所得配体与Ru(PPh3)3Cl2组成的催化体系在苯乙酮氧转移反应中的催化活性,发现氧化膦与Ru原位形成的催化剂比其还原态的三价膦组成的催化剂催化活性还高,二胺基取代的二氧化膦配体具有较高的催化活性,TON可达273.而采用先制备催化剂再催化反应时配体6的钌络合物催化活性TON可达352.     

金鸡纳碱衍生物钌催化剂催化芳香酮不对称氢转移反应

本文将系列金鸡纳碱及其衍生物与过渡金属钌配合物用于芳香酮不对称氢转移反应。考察了金鸡纳碱结构、催化剂用量、反应温度和时间等因素对不对称转移加氢反应的影响。结果表明,金鸡纳碱及其衍生物与金属钌的配合物对芳香酮不对称氢转移反应具有较好的催化作用,在优化的反应条件下转移加氢反应的对映选择性达51%~93%。在催化剂5次循环使用中,苯乙酮转移加氢产物对映选择性基本保持不变。     

钌(II)-吡啶基NNN配合物催化酮的室温(不对称)氢转移反应

合成了一种基于吡啶骨架含有苯并咪唑和手性咪唑啉基团的三齿NNN配体及其二价钌(II)配合物,通过核磁共振波谱学和X射线单晶晶体结构测定确认了钌(II)配合物的分子结构.这些配合物在室温下催化酮的氢转移反应,表现出了优异的催化活性,收率和ee值最高分别可达99%和97%.     

新型苯并咪唑取代的丙烯腈衍生物的催化合成

从邻苯二胺出发,合成了2-腈甲基苯并咪唑,对2-腈甲基苯并咪唑与醛的Knoevenagel缩合反应催化剂进行了优选,研究表明,吗啡啉/乙酸是催化2-腈甲基苯并咪唑与芳香醛Knoevenagel缩合反应的良好催化剂;在吗啡啉/乙酸催化下,合成了新型的双苯并咪唑丙烯腈衍生物和3-吲哚-2-苯并咪唑丙烯腈衍生物;将2-腈甲基苯并咪唑经过碱性水解,酯化,得到苯并咪唑乙酸乙酯,后者经过次序Knoevenagel缩合/分子内酯交换高产率地得到了新型的苯并咪唑取代的香豆素衍生物。     

手性相转移催化剂的合成及其在氨基酸烷基化反应中的应用

以2-叔丁基-5-甲基苯酚为原料,经4步反应制得2,2'-二甲基-3,3'-取代基-4,4'-二甲氧基-5,5'-二叔丁基-1,1'-联苯(6a~6g);6经溴化反应制得2,2'-二溴甲基-3,3'-取代基-4,4'-二甲氧基-5,5'-二叔丁基-1,1'-联苯(7a~7g);7与(R)-(+)-N-甲基-1-(1-萘基)乙基胺经环合反应合成了7种具有联苯结构的手性相转移催化剂(9a~9g)。6f,6g,7f,7g,9f和9g为新化合物,其结构经1H NMR,13C NMR和MS表征。以N-二苯基亚甲基甘氨酸叔丁酯的不对称烷基化为探针反应,考察了9a~9g的催化活性。结果表明:在催化剂用量为1mol%时,9g的催化性能最好,产率和对映选择性分别为80%和70%。     

铱配合物催化下不饱和仲醇的氢转移反应

报导了IrH5(i-Pr3P)2(1)对不饱和仲醇的反应, 发现(1)可以催化分子内氢转移反应, 使不饱和仲醇转变为酮, 讨论了这一反应机理.     

超声波促进的水相Biginelli反应合成二氢嘧啶酮衍生物

报道了水相中硫酸氢钠催化的乙酰乙酸酯、醛和脲（硫脲）参与的Biginelli型反应,在超声波促进下高效地合成11个3,4-二氢嘧啶酮衍生物,收率80%~93%,其结构经¹H NMR和HR-MS确证。     

硝酸铈铵催化绿色合成N1-取代的二氢嘧啶酮衍生物

无溶剂、80 ~oC条件下,硝酸铈铵催化化学计量的芳香醛、乙酰乙酸乙酯(乙酰乙酸甲酯)和单取代(硫)脲三组分"一锅法"合成了N1-取代的3,4-二氢嘧啶-2(1H)-酮衍生物。考察了催化剂用量和反应温度对产率的影响。产品结构通过IR,~1H NMR,~(13)C NMR,元素分析和X-射线单晶衍射进行了确证。该合成方法具有反应时间短,条件温和,产率高,方法绿色等优点。     

新型吡啶类苯并咪唑衍生物的合成

合成了一系列取代吡啶亚甲基硫代苯并咪唑类衍生物 ,并在过氧乙酸的氧化下得到其相应的亚砜类化合物 ,收率较好 (76%～ 93 % ) .代替了用间氯过氧苯甲酸进行氧化 ,反应过程稳定 ,降低了成本 .产品的结构经元素分析、IR和1HNMR表征 .     

苯并咪唑萘酰亚胺类化合物的合成与结构确证

本文合成并分离提纯了1位和4位单取代的苯并咪唑萘酰亚胺(NBI)类化合物1～4,对化合物1的紫外-可见光谱、红外光谱、质谱、核磁共振谱(包括1H NMR、13C NMR、DEPT、1H-13C HSQC、1H-13C HMBC、1H-1HCOSY多种NMR技术)进行了详细解析,对其所有的1H和13C NMR信号进行了归属,并使用了GIAO和CSGT两种方法量化计算核磁位移,通过多种波谱学技术确证了化合物的结构。     

Microwave-assisted Syntheses and Crystal Structures of Benzimidazole Thiazolinone Derivatives

A rapid and efficient microwave-assisted synthesis method for the preparation of 3-(1H-benzo[d]imidazol-2-yl)-2-substituted phenyl thiazolidin-4-one (4a, 4b) was described. The structures of 4a and 4b were determined by elemental analyses, IR, 1H NMR and X-ray diffraction. In the crystals of compounds 4a and 4b, the imidazole ring and two benzene rings are planar. Interestingly, the dihedral angle between two benzene rings is 71.5° in 4a, while it is almost perpendicular in 4b due to the different benzene substituents. Meanwhile, the thiazolidinone ring is planar in 4a while slightly distorted with an r.m.s deviation of 0.1494(2) in 4b. The hydrogen bonding interactions observed link the molecules to form a dimeric unit, which may be effective in the stabilization of the structure.     

Ligand Effect in Alkali-Metal-Catalyzed Transfer Hydrogenation of Ketones

This work unveils the reactivity patterns, as well as ligand and additive effect on alkali-metal-base-catalyzed transfer hydrogenation of ketones. Crucially to this reactivity is the presence of a Lewis acid (alkali cation), as opposed to a simple base effect. With aryl ketones, the observed reactivity order is Na⁺>Li⁺>K⁺, whereas for aliphatic substrates it follows the expected Lewis acidity, Li⁺>Na⁺>K⁺. Importantly, the reactivity pattern can be drastically changed by adding ligands and additives. Kinetic, labelling, and competition experiments as well as DFT calculations suggested that the reaction proceeds through a concerted direct hydride-transfer mechanism, originally suggested by Woodward. The lithium cation was found to be intrinsically more active than heavier congeners, but in the case of aryl ketones a decrease in reaction rate was observed at ≈40 % conversion with lithium cations. Noncovalent-interaction analysis revealed that this deceleration effect originated from specific noncovalent interactions between the aryl moiety of 1-phenylethanol and the carbonyl group of acetophenone, which stabilize the product in the coordination sphere of lithium and thus poison the catalyst. The ligand/additive effect is a complicated phenomenon that includes a combination of several factors, such as the decrease of activation energy by ligation (confirmed by distortion/interaction calculations of N,N,N’,N’-tetramethylethylenediamine, TMEDA) and the change in relative stabilization of reagents and substrates in the solution and the coordination sphere of the metal. Finally, we observed that lithium-base-catalyzed transfer hydrogenation can be further facilitated by the addition of an inexpensive and benign reagent, LiCl, which likely operates by re-initiating the reaction on a new lithium center.     

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.     

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.     

新型“NH-叔丁亚砜-烯”配体的合成及其在转移氢化反应中的应用

邻叔丁基亚砜苄胺与2-乙烯基苯甲醛(或2-苯乙烯-苯甲醛)经缩合反应制得亚胺,再经硼氢化钠还原合成了两个新型的NH-叔丁亚砜-烯类三齿柔性配体(4a和4b),其结构经1H NMR,13C NMR和HR-MS表征。考察了4a或4b与Ir的络合物催化苯乙酮的转移氢化反应,转化率分别为94%和51%。     

Catalytic Transfer Hydrogenation of Unsaturated Ketones and Imides via Ammonium Formate

Ammonium formate in acetic acid in presence of Pd-C catalyst efficiently converts open chain α,β-unsaturated ketones and cyclic enones to their saturated ketone analogues. The system converts enimides to saturated imides. An unsaturated non-conjugated cyclic dienone was also reduced by this system.     

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.