Cu-Catalyzed alkylation–cyanation type difunctionalization of styrenes with aliphatic aldehydes and TMSCN via decarbonylation

A copper-catalyzed decarbonylative alkylation–cyanation of styrene derivatives with aliphatic aldehydes and trimethylsilyl cyanide to provide chain elongated nitriles is reported. Using TBHP as oxidant and free radical initiator, the reaction...

Strecker Synthesis of α-aminonitriles Facilitated by N-methyl Imidazolium Acetate

N-Methyl imidazolium acetate [HMIm]OAc was simply prepared through reaction of N-methyl imidazole with acetic acid and it was applied as a media and promoter for Strecker synthesis of α-aminonitriles. The three component reaction of a variety of structurally different aldehydes and amines with trimethylsilyl cyanide (TMSCN) in the presence of [HMIm]OAc were evaluated. Reaction of aromatic aldehydes and cinnamaldehyde with either aromatic and aliphatic amines provided the corresponding α-aminonitriles in high to excellent isolated yields after short period of time at room temperature.

Metal(II) Coordination Polymers from Tetracarboxylate Linkers: Synthesis, Structures, and Catalytic Cyanosilylation of Benzaldehydes

Three 2D coordination polymers, [Cu2(µ4-dpa)(bipy)2(H2O)]n∙6nH2O (1), [Mn2(µ6-dpa)(bipy)2]n (2), and [Zn2(µ4-dpa)(bipy)2(H2O)2]n·2nH2O (3), were prepared by a hydrothermal method using metal(II) chloride salts, 3-(2′,4′-dicarboxylphenoxy)phthalic acid (H4dpa) as a linker, as well as 2,2′-bipyridine (bipy) as a crystallization mediator. Compounds 1–3 were obtained as crystalline solids and fully characterized. The structures of 1–3 were established by single-crystal X-ray diffraction, revealing 2D metal-organic networks of sql, 3,6L66, and hcb topological types. Thermal stability and catalytic behavior of 1–3 were also studied. In particular, zinc(II) coordination polymer 3 functions as a highly active and recoverable heterogeneous catalyst in the mild cyanosilylation of benzaldehydes with trimethylsilyl cyanide to give cyanohydrin derivatives. The influence of various parameters was investigated, including a time of reaction, a loading of catalyst and its recycling, an effect of solvent type, and a substrate scope. As a result, up to 93% product yields were attained in a catalyst recoverable and reusable system when exploring 4-nitrobenzaldehyde as a model substrate. This study contributes to widening the types of multifunctional polycarboxylic acid linkers for the design of novel coordination polymers with notable applications in heterogeneous catalysis.

Silyl Cyanopalladate-Catalyzed Friedel–Crafts-Type Cyclization Affording 3-Aryloxindole Derivatives

Abstract3-Aryloxindole derivatives were synthesized through a Friedel–Crafts-type cyclization. The reaction was catalyzed by a trimethylsilyl tricyanopalladate complex generated in situ from trimethylsilyl cyanide and Pd(OAc)2. Wide varieties of diethyl phosphates derived from N-arylmandelamides were converted almost quantitatively into oxindoles. When N,N-dibenzylamide was used instead of an anilide substrate, a benzo-fused δ-lactam was obtained. An oxindole product was subjected to substitution reactions to afford 3,3-diaryloxindoles with two different aryl groups.

Kinetic Insights into Cyanosilylation of Aldehydes Catalyzed by a Covalently Bridged Dinuclear (Salen)titanium Complex

Enantioselective addition of trimethylsilyl cyanide (TMSCN) to aldehydes is one of the most extensively studied organic reactions in asymmetric catalysis. Herein, we report our intensive kinetic investigation on the asymmetric addition of TMSCN to benzaldehyde, catalyzed by a covalently bridged dinuclear (salen)titanium complex <b>2</b>, which has been one of the most efficient artificial chiral catalysts reported so far for this reaction. It was found that the method of initial rates for kinetic investigation is not appropriate in this case because of the presence of a significant <a></a><a>incubation </a>period in the catalysis, while the method of progress rates proved to be more reliable and efficient for judging the kinetic orders of this catalytic system. The kinetic results revealed that <a>the reaction follows first order with respect to the catalyst</a> and is nearly independent of concentrations of both benzaldehyde and TMSCN<a>. A detailed catalytic mechanism for cyanosilylation of benzaldehyde in the presence of <b>2</b> was proposed, wherein the key active dinuclear species works in a cooperative manner for dual activation of both reactants.</a>

Kinetic Insights into Cyanosilylation of Aldehydes Catalyzed by a Covalently Bridged Dinuclear (Salen)titanium Complex

Enantioselective addition of trimethylsilyl cyanide (TMSCN) to aldehydes is one of the most extensively studied organic reactions in asymmetric catalysis. Herein, we report our intensive kinetic investigation on the asymmetric addition of TMSCN to benzaldehyde, catalyzed by a covalently bridged dinuclear (salen)titanium complex <b>2</b>, which has been one of the most efficient artificial chiral catalysts reported so far for this reaction. It was found that the method of initial rates for kinetic investigation is not appropriate in this case because of the presence of a significant <a></a><a>incubation </a>period in the catalysis, while the method of progress rates proved to be more reliable and efficient for judging the kinetic orders of this catalytic system. The kinetic results revealed that <a>the reaction follows first order with respect to the catalyst</a> and is nearly independent of concentrations of both benzaldehyde and TMSCN<a>. A detailed catalytic mechanism for cyanosilylation of benzaldehyde in the presence of <b>2</b> was proposed, wherein the key active dinuclear species works in a cooperative manner for dual activation of both reactants.</a>

ZnO-nanorods Promoted Synthesis of α-amino Nitrile Benzofuran Derivatives using One-pot Multicomponent Reaction of Isocyanides

Aims & Objective: In this work ZnO-nanorod (ZnO-NR) as reusable catalyst promoted Strecker-type reaction of 2,4-dihydroxyacetophenone, isopropenylacetylene, trimethylsilyl cyanide (TMSCN), primary amines and isocyanides at ambient temperature under solvent-free conditions and produced α-amino nitriles benzofuran derivatives in high yields. These synthesized compounds may have antioxidant ability. Materials and Methods: ZnO-NRs in these reactions were prepared according to reported article. 2,4-dihydroxyacetophenone 1 (2 mmol) and isopropenylacetylene 2 (2 mmol) were mixed and stirred for 30 min in the presence of ZnO-NR (10 mol%) under solvent-free conditions at room temperature. After 30 min, primary amine 3 (2 mmol) was added to the mixture gently and the mixture was stirred for 15 min. After this time TMSCN 4 (2 mmol) was added to the mixture and stirred for 15 min. After completion of the reaction, as indicated by TLC, isocyanides 5 was added to mixture in the presence of catalyst. Results: In the first step of this research, the reaction of 2,4-dihydroxyacetophenone 1, isopropenylacetylene 2, methyl amine 3a, trimethylsilyle cyanide 4 and tert-butyl isocyanides 5a was used as a sample reaction to attain the best reaction conditions. The results showed this reaction performed with catalyst and did not have any product without catalyst after 12 h. Conclusion: In conclusion, we investigate multicomponent reaction of 2,4-dihydroxyacetophenone 1, isopropenylacetylene 2, primary amines 3, trimethylsilyl cyanide 4 and isocyanides along with ZnO-NRs as reusable catalyst at room temperature under solvent-free conditions which generates α-amino nitrile benzofuran derivatives in high yields. The advantages of our method are high atom economy, green reaction conditions, higher yield, shorter reaction times, and easy work-up, which are in good agreement with some principles of green chemistry. The compounds 8c exhibit excellent DPPH radical scavenging activity and FRAP compared to synthetic antioxidants BHT and TBHQ.