KF负载氧化物高效催化缺电子烯与胺类的共轭加成反应

提供了一种新型高效的催化缺电子烯与胺类的共扼加成的反应体系。首先合成了一系列负载型氟化钾固体碱,并用于催化上述反应。通过对不同载体选择考察,筛选出氟化钾负载氧化镁固体碱为最佳催化剂。在进一步的催化反应过程中发现,该催化剂对反应具有很高的催化活性,能催化该反应在短短数分钟内完成。操作简单方便,不需要任何溶剂,催化剂价格低廉,反应收率高,可重复使用,具有化学选择性,适用范围广泛等均为该催化体系的主要特征。     

Highly efficient heterogeneous procedure for the conjugate addition of amines to electron deficient alkenes

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. K₂CO₃ supported on different carriers have been synthesized for the conjugate addition of amines and alkenes. After optimizing the reaction conditions, K₂CO₃/MgO was chosen as the most efficient catalyst for the reactions. The results showed that the catalyst was very efficient for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes. Operational simplicity, without need of any solvent, low cost of the catalyst used, high yields, reusability, excellent chemoselectivity, and applicability to large-scale reactions are the key features of this methodology. Supported by the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science and Technology of China (Grant No. 2006BAE03B06), Shanghai Leading Academic Discipline Project (Grant No. B409), and Shanghai International Cooperation of Science and Technology Project (Grant No. 06SR07101)     

A Facile Procedure for Conjugate Addition of Amines to Electron Deficient Alkenes with Metal Oxide as Catalyst

A novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. A series of metal oxides was synthesized for catalyzing the conjugate addition of amines and alkenes. After optimizing the reaction conditions, SrO was chosen as the most efficient catalyst for the reactions. The results show that the catalyst is very efficient for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes. Operational simplicity...     

Highly efficient procedure for the conjugate addition of amines to electron deficient alkenes

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. The results showed that the catalyst was very efficient for the reactions with the excellent yields in several minutes. Operational simplicity, without need of any solvent, low cost of the catalyst used, high yields, reusability, excellent chemoselectivity, applicability to large-scale reactions are the key features of this methodology. The article is published in the original.     

Bromodimethylsulfonium bromide mediated Michael addition of amines to electron deficient alkenes

Bromodimethylsulfonium bromide has been found to be an efficient catalyst for the Michael addition of a wide variety of amines to electron deficient alkenes at room temperature. The protocol is very simple and chemoselective. Aliphatic and benzylic amines undergo conjugate addition within a very short period under solvent-free conditions and provide excellent yields of products.     

Multicomponent Reactions with Cyclic Tertiary Amines Enabled by Facile C−N Bond Cleavage

A novel and catalyst‐free multicomponent reaction with cyclic tertiary amines, electron‐deficient aryl halides or heteroaromatic halides, and Na₂S enabled by facile C−N bond cleavage of the cyclic tertiary amines was developed. This direct and operationally simple method can be applied with a wide range of functional groups and provides an efficient and rapid approach to potentially drug‐like products containing amine, azaarene, thioether, or phenol ether functionalities in good to excellent yields. The utility of this method was demonstrated by the rapid synthesis of the analgesic ruzadolane.     

Bifunctional Heterogeneous Catalysis of Silica–Alumina‐Supported Tertiary Amines with Controlled Acid–Base Interactions for Efficient 1,4‐Addition Reactions

We report the first tunable bifunctional surface of silica–alumina‐supported tertiary amines (SA–NEt₂) active for catalytic 1,4‐addition reactions of nitroalkanes and thiols to electron‐deficient alkenes. The 1,4‐addition reaction of nitroalkanes to electron‐deficient alkenes is one of the most useful carbon–carbon bond‐forming reactions and applicable toward a wide range of organic syntheses. The reaction between nitroethane and methyl vinyl ketone scarcely proceeded with either SA or homogeneous amines, and a mixture of SA and amines showed very low catalytic activity. In addition, undesirable side reactions occurred in the case of a strong base like sodium ethoxide employed as a catalytic reagent. Only the present SA‐supported amine (SA–NEt₂) catalyst enabled selective formation of a double‐alkylated product without promotions of side reactions such as an intramolecular cyclization reaction. The heterogeneous SA–NEt₂ catalyst was easily recovered from the reaction mixture by simple filtration and reusable with retention of its catalytic activity and selectivity. Furthermore, the SA–NEt₂ catalyst system was applicable to the addition reaction of other nitroalkanes and thiols to various electron‐deficient alkenes. The solid‐state magic‐angle spinning (MAS) NMR spectroscopic analyses, including variable‐contact‐time ¹³C cross‐polarization (CP)/MAS NMR spectroscopy, revealed that acid–base interactions between surface acid sites and immobilized amines can be controlled by pretreatment of SA at different temperatures. The catalytic activities for these addition reactions were strongly affected by the surface acid–base interactions.     

Zirconyl triflate: A new, highly efficient and reusable catalyst for acetylation and benzoylation of alcohols, phenols, amines and thiols with acetic and benzoic anhydrides

Highly efficient acetylation and benzoylation of alcohols, phenols, amines and thiols with acetic and benzoic anhydrides catalyzed by new and reusable zirconyl triflate, ZrO(OTf)₂, is reported. The high catalytic activity of electron deficient ZrO(OTf)₂ can be used for the acetylation and benzoylation of not only primary alcohols but also sterically-hindered secondary and tertiary alcohols with acetic and benzoic anhydrides. Acetylation of phenols with acetic and benzoic anhydrides was achieved to afford the desired acetates and benzoates efficiently. This catalyst also efficiently catalyzed the acetylation and benzoylation of amines and thiols whereby the corresponding amides and thioesters were obtained in good to excellent yields. This catalyst can be reused several times without loss of its activity.     

An efficient biomaterial supported bifunctional organocatalyst (ES-SO3- C5H5NH+) for the synthesis of β-amino carbonyls

A biomaterial supported organocatalyst, readily synthesized by the reaction of chemically modified sulfonic group containing expanded corn starch with pyridine exhibited excellent catalytic activity for the synthesis of β-amino carbonyls in excellent yields via aza-Michael addition of amines to electron deficient alkenes. A remarkable enhancement in the reaction rates was observed with the prepared bifunctional organocatalyst in comparison to the either starch grafted sulfonic acid or the corresponding homogeneous pyridinium p-toluenesulfonate.     

Development,Scope and Mechanisms of Multicomponent Reactions of Asymmetric Electron‐Deficient Alkynes with Amines and Formaldehyde

Based on the reactive behaviour of the substrates, two synthetic routes to polysubstituted pyrimidine derivatives are presented herein: 1) A catalyst‐free multicomponent reaction of electron‐deficient alkynes, aliphatic amines and formaldehyde and 2) Ag^I‐catalyzed synthesis of pyrimidines from electron‐deficient alkynes, anilines and formaldehyde by a domino reaction. Under optimized conditions, the multicomponent reactions were accomplished with high regioselectivity and excellent yields. A computational study was carried out by using the B3LYP density functional theory to elucidate the mechanisms of the catalyst‐free hydroamination reaction. Calculations showed the activation free energies of aliphatic amines were lower than those of anilines, which is consistent with the experimental results.     

Chemo/regioselective Aza-Michael additions of amines to conjugate alkenes catalyzed by polystyrene-supported AlCl3

A simple and efficient procedure is presented for Aza-Michael additions of various amines with conjugate alkenes bearing electron withdrawing group catalyzed by polystyrene-supported aluminum chloride (Ps-AlCl₃) without the use of any solvents. The catalyst shows high catalytic activity for both aromatic amines and aliphatic amines. Chemoselective additions of the two types of amines with conjugate alkenes are achieved. Regioselective additions of two different amino groups in one molecule proceed smoothly. Ps-AlCl₃ has better recyclability and can be reused several times without apparent loss of activity.     

Cobalt-Catalyzed Enantioselective Hydroamination of Arylalkenes with Secondary Amines

Catalytic asymmetric hydroamination of alkenes with Lewis basic amines is of great interest but remains a challenge in synthetic chemistry. Here, we developed a Co-catalyzed asymmetric hydroamination of arylalkenes directly using commercially accessible secondary amines. This process enables the efficient access to valuable α-chiral tertiary amines in good to excellent yields and enantioselectivities. Mechanistic studies suggest that the reaction includes a CoH-mediated hydrogen atom transfer (MHAT) with arylalkenes, followed by a pivotal catalyst controlled S_N2-like pathway between in situ generated electrophilic cationic alkylcobalt(IV) species and free amines. This radical-polar crossover strategy not only provides a straightforward and alternative approach for the synthesis of enantioenriched α-tertiary amines, but also underpins the substantial opportunities in developing asymmetric radical functionalization of alkenes with various free nucleophiles in oxidative MHAT catalysis.     

Glycerol Boosted Rh-Catalyzed Hydroaminomethylation Reaction: A Mechanistic Insight

We report a Rh-catalyzed hydroaminomethylation reaction of terminal alkenes in glycerol that proceeds efficiently under mild conditions to produce the corresponding amines in relatively high selectivity towards linear amines, moderate to excellent yields by using a low catalyst loading (1 mol % [Rh], 2 mol % phosphine) and relative low pressure (H₂/CO, 1:1, total pressure 10 bar). This work sheds light on the importance of glycerol in enabling enamine reduction via hydrogen transfer. Moreover, evidence for the crucial role of Rh as chemoselective catalyst in the condensation step has been obtained for the first time in the frame of the hydroaminomethylation reaction by precluding deleterious aldol condensation reactions. The hydroaminomethylation proceeds under a molecular regime; the outcome of catalytically active species into metal-based nanoparticles renders the catalytic system inactive.     

Generation of C2F5CHN2 In Situ and Its First Reaction: [3+2] Cycloaddition with Alkenes

The novel chemical reagent, C₂F₅CHN₂, is generated in situ from C₂F₅CH₂NH₂ ? HCl and sodium nitrite. It reacts with mono‐ and disubstituted electron‐deficient alkenes at room temperature to afford C₂F₅‐pyrazolines in excellent yields.     

Homogeneous hydrogenation of electron‐deficient alkenes by iridium complexes

The catalytic homogeneous hydrogenation of electron‐deficient alkenes (nucleophilic hydrogenation) was achieved in the presence of iridium complexes and a base as co‐catalyst. Contrary to hydrogenation of electron‐rich alkenes, which is inactivated by bases, the hydrogenation of the electron‐deficient alkenes turned out to be base activated. Here, we present a more thorough study on the capacities but also limitations of this new reaction mechanism using screenings of the reaction conditions as well as different Ir complexes and substrates. The formation of a catalytically active Ir complex is proposed. The active complex usually attacks a soft electron‐deficient atom, if more than one possibility exists (as shown by density functional theory computations). Additionally, first examples of enantiomeric enrichments in the presence of chiral Ir complexes are presented. The high catalyst load needed and the moderate yields show that the active complex is very unstable under conditions of nucleophilic hydrogenation and is quickly deactivated, which has to be addressed in further studies. Copyright © 2011 John Wiley & Sons, Ltd.     

InBr3 Catalyzed intermolecular hydroamination of unactivated alkenes

InBr₃ has been demonstrated to be a simple catalyst for the intermolecular hydroamination of unactivated alkenes to produce tosyl- and mesyl-protected amines in moderate to good yields.     

Lithium tetrafluoroborate catalyzed highly efficient inter- and intramolecular aza-Michael addition with aromatic amines

Lithium tetrafluoroborate has been demonstrated for the first time to be an efficient catalyst in intermolecular aza-Michael addition aromatic amines to electron deficient alkenes. Suitability of the same catalyst in intramolecular aza-Michael addition leading 2-aryl-2,3-dihydroquinolin-4(1H) ones has also been described.     

Aza-Michael addition of aliphatic or aromatic amines to α,β-unsaturated compounds catalyzed by a DBU-derived ionic liquid under solvent-free conditions

A task-specific ionic liquid, 1,8-diazabicyclo[5.4.0]-undec-7-en-8-ium acetate has been successfully used as a catalyst for aza-conjugate addition of aliphatic or aromatic amines to various electron deficient alkenes under solvent-free conditions and at room temperature. The catalyst can be reused for six times without noticeable loss of activity.     

Ni-nanoparticles: an efficient green catalyst for chemoselective reduction of aldehydes

A novel method for reduction of aromatic and heteroaromatic aldehydes with ammonium formate using Ni-nanoparticles is described. The Ni-nanoparticles act as a green catalyst for selective reduction of the aldehydic group in the presence of other functional groups, viz.: -NO₂, -CN and alkenes to give the corresponding alcohols in excellent yields.     

Direct Aminophosphonylation of aldehydes catalyzed by cyclopentadienyl ruthenium(II) complexes

This work reports a novel method for the direct aminophosphonylation of aldehydes catalyzed by cyclopentadienyl ruthenium(II) complexes. The system HP(O)(OEt)₂/[CpRu(PPh₃)₂Cl] was very efficient for the aminophosphonylation of aldehydes with primary and secondary amines, producing the corresponding α-aminophosphonates in good to excellent yields. This novel method has several advantages including the use of a small amount of catalyst (0.5?mol%), high chemoselectivity, solvent-free conditions and application of the catalyst [CpRu(PPh₃)₂Cl] for at least 12 cycles with excellent activity.