酰基镍作为关键中间体参与的酰基还原制备酮的研究进展

酰基镍是金属有机合成中的一类重要中间体,近些年来,以酰基镍为中间体的还原酰基化反应合成酮的策略引起了广泛地关注.相较于金属亲核试剂参与的传统交叉偶联反应,还原酰基化反应具有条件温和、步骤经济性高、官能团兼容性良好、环境友好等优点.对近些年来镍催化羧酸或羧酸衍生物和各种亲电试剂的还原酰基化合成酮的最新研究进行了概述.     

利伐沙班中间体的合成工艺研究

本文以溴苯为起始原料,经Ullmann反应、N-酰基化、吗啉酮环合、芳环硝基化、芳硝基还原、2-噁唑烷酮环合共六步反应制得了利伐沙班的关键中间体,所得目标化合物经质谱、核磁共振氢谱确认,总收率达到44.50%。     

芴羟甲基化合成9-芴甲醇过程中脱水产物生成的影响因素及机理

以多聚甲醛为羟甲基化试剂,在碱催化下芴一步生成9-芴甲醇过程极易发生单分子共轭碱消除,脱水生成富烯化合物,导致9-芴甲醇的选择性下降.为实现对该过程的调控,本文考察了温度、碱的种类、乙醇和多聚甲醛的添加等对9-芴甲醇脱水反应的影响,并结合动力学计算和同位素示踪,推测了芴羟甲基化合成9-芴甲醇过程中副产物生成的机理.结果表明,升高温度、增加碱性和添加甲醛有利于脱水反应发生.乙醇通过氢键作用促进脱水反应,添加量大时会导致芴负离子和9-芴甲醇负离子发生质子化作用.中间体可能会发生分子内氢传递或者夺取芴和9-芴甲醇的9位氢,促进脱水反应发生.     

催化量SmI3促进的芳烃酰基化反应

自从Kagan将二碘化钐应用于有机合成以来,钐试剂在有机合成中的应用的研究引起了人们的很大兴趣.随着研究的深入,金属钐、二碘化钐、三碘化钐、有机钐等钐试剂在有机合成中的应用越来越广泛[1].我们课题组也研究了三碘化钐促进的一些有机合成反应[2,3].Friedel-Crafts酰基化反应是合成芳酮的重要反应,但在传统的Lewis酸催化的芳烃酰基化反应中,由于络合作用等的影响,存在着催化剂的用量过大、副反应多、选择性差等不足[4].高效、催化量的催化剂的采用是人们期待的目标.本文报道用催化量的(10 mol%)SmI3促进的芳烃酰基化反应,反应方程式如下,产物的结构经IR和1HNMR所确证.     

UiO-67-Sal-CuCl2在空气中催化芳香醇的选择性氧化

利用水热法一步合成了金属有机骨架(MOFs)材料UiO-67-Sal, 并将3种铜盐固定在其表面, 研究了3种铜MOFs材料催化芳香醇选择性氧化的性能. 结果表明, UiO-67-Sal-CuCl₂催化剂对芳香醇选择性氧化反应具有良好的催化活性, 且在重复使用4次后, 依然保持较好的催化效果.     

O2促进下五元环烯胺的C—H亚胺化(英文)

报道了一个O₂促进下五元环烯胺的C—H亚胺化反应.在微波辐射下,季酮酸或1,3-环戊二酮衍生的烯胺酮、芳酮醛水合物和芳胺三组分参与的无金属催化反应进展顺利,以良好的产率和完全的立体选择性得到了一系列α-烯胺基-α-芳酰基亚胺衍生物.在该反应过程中,空气充当绿色氧化剂,水是唯一的副产物.     

可见光催化炔烃串联氰基烷基磺酰化/环化（英文）

报道了一种在无过渡金属条件下可见光催化炔烃与环酮肟衍生物的串联氰基烷基磺酰化/环化反应,通过SO_2的插入合成2-氰基烷基磺酰基-9H-吡咯并[1,2-a]吲哚.该碳碳叁键的双官能团化包括自由基机理,依次经历了亚胺自由基的形成、环酮的开环、SO_2的插入、磺酰基对碳碳叁键的加成、分子内环化和异构化.     

拟肾上腺素药盐酸甲氧明的绿色合成

以对苯二酚为原料经羟基的甲基化、傅克酰基化、肟化、肟基还原、酮胺氢化5步反应合成了盐酸甲氧明, 中间体和目标产物经核磁共振氢谱、红外光谱及元素分析仪确证了其化学结构, 总收率为37.6%. 与传统盐酸甲氧明工艺相比, 该工艺反应条件温和、简便、经济、产率高及对环境友好.     

可见光催化合成C-3位芳酰基取代的2-芳基-2H-吲唑衍生物

基于C-H键官能团化反应策略,在无过渡金属条件下,以2-芳基-2H-吲唑为底物,芳基酮酸为芳酰基自由基源,利用2,4,5,6-四(9-咔唑基)-间苯二腈(4CzIPN)作为光催化剂,通过可见光催化脱羧偶联反应,合成了一系列C-3位芳酰基取代的2-芳基-2H-吲唑衍生物,产率59%-81%。所得产物结构经过氢谱、碳谱和高分辨质谱表征确证。该方法反应条件温和,具有良好的底物适用性和官能团耐受性,为2H-吲唑的C-3位C-H键芳酰基化反应提供了新途径。     

氢硼化离子交换树脂-硼化镍(催化)还原芳香肟的反应研究

以氢硼化离子交换树脂为还原剂,甲醇作溶剂,加入催化量的醋酸镍,原位制备硼化镍催化剂的方法,还原芳香酮肟得到的产物为相应的α-取代苄胺,还原芳香醛肟得到的主要产物为双苄基仲胺,还原产物均经1HNMR,MS和元素分析确认.     

Selective hydrogenation of aromatic compounds using modified iridium nanoparticles

Till now, Ionic liquid‐stabilized metal nanoparticles were investigated as catalytic materials, mostly in the hydrogenation of simple substrates like olefins or arenes. The adjustable hydrogenation products of aromatic compounds, including quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes, are always of special interest, since they provide more choices for additional derivatization. Iridium nanoparticles (Ir NPs) were synthesized by the H₂ reduction in imidazolium ionic liquid. TEM indicated that the Ir NPs is worm‐like shape with the diameter around 12.2 nm and IR confirmed the modification of phosphine‐functionalized ionic liquids (PFILs) to the Ir NPs. With the variation of the modifier, solvent and reaction temperature, substrate like quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes could be hydrogenated by Ir NPs with interesting adjustable catalytic activity and chemoselectivity. Ir NPs modified by PFILs are simple and efficient catalysts in challenging chemoselective hydrogenation of quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes. The activity and chemoselectivity of the Ir NPs could be obviously impacted or adjusted by altering the modifier, solvent and reaction temperature.     

Hydroacylation of activated ketones catalyzed by N-heterocyclic carbenes

N-heterocyclic carbenes derived from triazolium salts are effective catalysts between 10 and 15 mol % for the hydroacylation of activated ketones. The reducing equivalent is generated via the interaction of a nucleophilic carbene species and an aromatic aldehyde. The subsequent alcohol product can undergo an acylation event with the resulting acyl heteroazolium intermediate formed in situ between the NHC and the aldehyde. This unprecedented multiple bond-forming reaction can accommodate aromatic aldehydes as the hydride source and various electron-deficient ketones. Preliminary mechanistic evidence indicates that the reduction and acylation steps are sequential operations. The intramolecular variant of this organocatalytic reaction affords benzofuranones in good yield.     

Reduction of Aromatic Aldehydes,Ketones with Acyloxy Substituent at the Ortho-position by NaBH4 in the Presence of Waters

n unusual reduction of some aromatic aldehydes, ketones by sodium borohydride was discovered. In a THF/H₂O or DMSO/H₂O solvent system the aromatic aldehydes, ketones with acyloxy substituent on the ortho-position to the carbonyl group can be reduced to the corresponding alkyl phenols. This unusual reduction is applicable also to the corresponding alcohols of all the above aldehydes, ketones. A putative mechanism was suggested. In addition to the above aldehydes, ketones, benzyl alcohols, certain 4-acyloxybenzyl esters(probably also the 2-substituted analogues) such as 4-benzoyloxybenzyl benzoate was also found to be reduced to methylphenol by this unusual reduction.     

Catalytic cross-coupling reaction of esters with organoboron compounds and decarbonylative reduction of esters with HCOONH4: a new route to acyl transition metal complexes through the cleavage of acyl-oxygen bonds in esters

The Ru3(CO)12-catalyed cross-coupling reaction of esters with organoboron compounds leading to ketones is described. A wide variety of functional groups can be tolerated under the reaction conditions. Aromatic boronates function as a coupling partner to give aryl ketones. Acyl-alkyl coupling to dialkyl ketones is also achieved by the use of 9-alkyl-9-BBN in place of boronates. The Ru3(CO)12-catalyzed decarbonylative reduction of esters with ammonium formate (HCOONH4) leading to hydrocarbons is also described. No expected aldehydes are produced, and controlled experiments indicate that aldehydes are not intermediate for the transformation. A hydrosilane can also be used as a reducing reagent in place of HCOONH4. A wide variety of functional groups are compatible for both reactions. The key step for both catalytic reactions is the directing group-promoted cleavage of an acyl carbon-oxygen bond in esters, leading to the generation of acyl transition metal alkoxo complexes.     

A practical synthesis of optically active aromatic epoxides via asymmetric transfer hydrogenation of α-chlorinated ketones with chiral rhodium-diamine catalyst

A practical method for the synthesis of optically active aromatic epoxides has been developed via the formation of optically active α-chlorinated alcohols and intramolecular etherification. Optically active alcohols with up to 99% ee can be obtained from the asymmetric reduction of aromatic ketones with a substrate/catalyst ratio of 1000-5000 using a formic acid/triethylamine mixture containing a well-defined chiral Rh complex, Cp*RhCl[(R,R)-Tsdpen]. The asymmetric reduction of α-chlorinated aromatic ketones with a chiral Rh catalyst is characterized by a rapid and carbonyl group-selective transformation because of the coordinatively saturated nature of diamine-based Cp*Rh(III) hydride complexes. The outcome of the reduction is significantly influenced by the structures of the ketonic substrates as well as the hydrogen source such as formic acid or 2-propanol. Commercially available reagents and solvents can be used in this reaction without special purification. This epoxide synthetic process in either a one- or two-pot procedure is practical and particularly useful for the large-scale production of optically active styrene oxides from α-chlorinated ketones.     

The NHCs-mediated cross-coupling of aromatic aldehydes with benzyl halides: synthesis of α-aryl ketones

A new NHCs-mediated synthetic method was found to produce α-aryl ketones in 22-63% yields in one-pot process from the corresponding aromatic aldehydes and benzyl halides. This method is the first example of the NHCs-mediated intermolecular nucleophilic acylation of aromatic aldehydes with benzyl halides.     

Kinetics of catalytic Meerwein-Ponndorf-Verley reduction of aldehydes and ketones using boron triethoxide

Catalytic Meerwein-Ponndorf-Verley (MPV) reduction of various aliphatic, aromatic, and unsaturated aldehydes and ketones to corresponding alcohols (analyzed by GC-MS) in the presence of boron triethoxide (B(OEt)₃) were studied. Kinetics of this reduction reaction was also studied and the respective rate constants were determined. It was found that B(OEt)₃ catalyzes the reduction of aliphatic aldehydes and ketones to alcohols at room temperature while aromatic aldehydes and ketones were not reduced under the same conditions. In addition, MPV reduction using B(OEt)₃ was found to be chemoselective as unsaturated aldehydes and ketones afforded the corresponding alcohols without affecting unsaturated groups. The mechanism proposed involves a six-membered transition state in which both the alcohol and the carbonyl are coordinated to the same boron centre of a boron alkoxide catalyst.     

Preparation of phenyl-butyraldehydes using a base-catalyzed aromatization of dienones

Seven aldehydes were prepared using a five-step sequence synthesis. The synthetic strategy involved the use of a novel aromatization reaction of dienones. These key intermediates were prepared following a sequence involving BAR of substituted tetralones, ketones reduction, protection of alcohol, and bis-allylic oxidation. The key step of the route is an aromatization promoted by basic reaction conditions of dienones leading to substituted 4-phenyl butanals.     

Silica Phosphoric Acid: An Efficient and Recyclable Catalyst for the Solvent-Free Synthesis of Acylals and Their Deprotection in MeOH

Silica phosphoric acid was used as an efficient, mild, and recyclable solid catalyst for the synthesis of acylals from various structurally diverse aldehydes and acetic anhydride under solvent-free conditions. The acylation of aldehydes was highly chemoselective, and no ketone was acylated, which provided a method for the synthesis of acylals from aldehydes in the presence of ketones. Silica phosphoric acid–catalyzed deprotection of acylals to the corresponding aldehydes in MeOH has also been developed with excellent yield. The deprotection of the acylals of aromatic aldehydes took priority over those of aliphatic aldehydes.     

SiO2 负载壳聚糖席夫碱钯催化剂催化芳香醛酮还原为芳香烃

 制备了 SiO2 负载的壳聚糖席夫碱钯催化剂, 利用 X 射线衍射、红外光谱和热重等方法对催化剂进行了表征, 并考察了该催化剂催化羰基加氢为亚甲基的反应性能, 以二苯甲酮为底物, 系统地研究了反应时间、反应温度和催化剂用量等因素对反应性能的影响. 结果表明, 该催化剂具有较高的催化芳香羰基加氢为亚甲基的活性和选择性, 且反应可在较低的温度和常压的温和条件下进行. 关键词：壳聚糖; 席夫碱;