5320-75-2Relevant academic research and scientific papers
Synthesis of cinnamyl benzoate over novel heteropoly acid encapsulated ZIF-8
Malkar, Radhika S.,Yadav, Ganapati D.
, p. 54 - 65 (2018)
ZIF-8 is a zeolitic imidazolate framework which is a subclass of metal organic framework (MOF). ZIF-8 is the emerging class of MOF with various applications. Dodecatungstophosphoric acid (DTP) encapsulated ZIF-8 was prepared first time using bottle around the ship strategy. This approach covers ZIF-8 synthesis along with DTP encapsulation in one pot synthesis. The synthesized catalyst shows highest catalytic activity for esterification reaction of benzoic anhydride with cinnamyl alcohol to form cinnamyl benzoate. Heterogeneous catalytic synthesis of cinnamyl benzoate with complete reaction kinetics is presented here for the first time. Cinnamyl benzoate is a famous perfumery and flavoring agent and GRAS listed food additive molecule. Catalyst preparation method is simple, rapid and can be done at room temperature using water as a solvent. DTP@ZIF-8 shows sodalite like structure and it was confirmed by applying several characterization techniques like SEM, TEM, XRD, BET, FTIR, TGA and ammonia-TPD. Duration of DTP@ZIF-8 crystal formation was studied and optimized up to 12 h. Catalyst is thermally stable up to 400 °C and showed reusability for 3 cycles. Reaction kinetics was studied with best fit of Eley-Rideal mechanism.
Superior activity and selectivity of multifunctional catalyst Pd-DTP@ZIF-8 in one pot synthesis of 3-phenyl propyl benzoate
Malkar, Radhika S.,Yadav, Ganapati D.
, p. 282 - 293 (2019)
The catalytic efficiency of zeolitic imidazolate framework (ZIF-8) has been explored by making it multifunctional. Dual active sites were incorporated such as acid (dodecatungstophosphoric acid, DTP) and metal (Pd°) to prepare 5% Pd-DTP@ZIF-8. DTP was encapsulated inside the cage of ZIF-8 by in-situ and bottle around the ship approach whereas Pd was loaded ex-situ by simple wet impregnation method. The catalytic efficiency was tested for one pot synthesis of 3-phenyl propyl benzoate (3-PPB), a perfumery compound, from cinnamyl alcohol and benzoic anhydride. Trans-esterification of cinnamyl alcohol with benzoic anhydride gives cinnamyl benzoate which on further hydrogenation gives 3-PPB. Three different supports were screened such as ZIF-8, K10 and MCF out of which ZIF-8 showed the maximum activity because of its high surface area and smaller pore diameter. Further Pd, Ni and Cu metals were studied for selective hydrogenation of C[dbnd]C bond among which 5% Pd-DTP@ZIF-8 gave almost 98% conversion of cinnamyl benzoate to 3-PPB with 93% selectivity. Fresh and spent catalysts were characterized by various techniques. 5% Pd-DTP@ZIF-8 showed anti-leaching property with great thermal stability. The turn over frequency and turn over number of the catalyst was observed to be 0.058 s?1 and 835, respectively. A kinetic model was developed with good fit using LHHW mechanism and the activation energy calculated as 17.45 kcal/mol for hydrogenation step. Thus, the reaction was found to be kinetically controlled. The entire process is green.
Photochemical Activation of Aromatic Aldehydes: Synthesis of Amides, Hydroxamic Acids and Esters
Nikitas, Nikolaos F.,Apostolopoulou, Mary K.,Skolia, Elpida,Tsoukaki, Anna,Kokotos, Christoforos G.
supporting information, p. 7915 - 7922 (2021/05/03)
A cheap, facile and metal-free photochemical protocol for the activation of aromatic aldehydes has been developed. Utilizing thioxanthen-9-one as the photocatalyst and cheap household lamps as the light source, a variety of aromatic aldehydes have been activated and subsequently converted in a one-pot reaction into amides, hydroxamic acids and esters in good to high yields. The applicability of this method was highlighted in the synthesis of Moclobemide, a drug against depression and social anxiety. Extended and detailed mechanistic studies have been conducted, in order to determine a plausible mechanism for the reaction.
Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
supporting information, p. 16470 - 16485 (2021/10/20)
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
, p. 66 - 71 (2020/11/18)
The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
Sustainable Palladium-Catalyzed Tsuji-Trost Reactions Enabled by Aqueous Micellar Catalysis
Braga, Felipe C.,Gallou, Fabrice,Lee, Nicholas R.,Lippincott, Daniel J.,Lipshutz, Bruce H.,Moghadam, Farbod A.,Zhu, Bingchun
supporting information, (2020/07/15)
Palladium-catalyzed allylic substitution, or "Tsuji-Trost"reactions, can be run under micellar catalysis conditions featuring not only chemistry in water but also numerous combinations of reaction partners that require low levels of palladium, typically on the order of 1000 ppm (0.1 mol %). These couplings are further characterized by especially mild conditions, leading to a number of cases not previously reported in an aqueous micellar medium. Inclusion of diverse nucleophiles, such as N-H heterocycles, alcohols, dicarbonyl compounds, and sulfonamides is described. Intramolecular cyclizations further illustrate the broad utility of this process. In addition to recycling studies, a multigram scale example is reported, indicative of the prospects for scale up.
Catalytic conversion of ketones to esters: Via C(O)-C bond cleavage under transition-metal free conditions
Subaramanian, Murugan,Ramar, Palmurukan M.,Rana, Jagannath,Gupta, Virendra Kumar,Balaraman, Ekambaram
supporting information, p. 8143 - 8146 (2020/09/09)
The catalytic conversion of ketones to esters via C(O)-C bond cleavage under transition-metal free conditions is reported. This catalytic process proceeds under solvent-free conditions and offers an easy operational procedure, broad substrate scope with excellent selectivity, and reaction scalability. This journal is
Asymmetric Synthesis of α-Quaternary γ-Lactams through Palladium-Catalyzed Asymmetric Allylic Alkylation
Song, Tao,Arseniyadis, Stellios,Cossy, Janine
supporting information, p. 603 - 607 (2019/02/28)
The synthesis of chiral unsaturated γ-lactams is reported featuring a highly enantioselective palladium-catalyzed asymmetric allylic alkylation of α, γ-disubstituted 2-silyloxypyrroles. This method allows a straightforward access to optically active γ-lactams bearing an α-quaternary stereogenic center in high yields (up to 93%), high regioselectivities (up to >20:1), and excellent enantioselectivities (up to 95% ee). To further demonstrate the synthetic utility of the method, the resulting allylated products were converted to various versatile chiral building blocks, such as pyrrolidines and pyrrolidinones.
Dibromination of alkenes with LiBr and H2O2 under mild conditions
Martins, Nayara Silva,Alberto, Eduardo E.
supporting information, p. 161 - 167 (2017/12/28)
Electron-rich and electron-poor alkenes, and alkenes bearing protecting groups can be efficiently and stereoselectively converted to trans-dibromides using LiBr/H2O2 and AcOH as a proton source in 1,4-dioxane. For most substrates addition of 0.1 mol% of PhTeTePh enhances the reaction rate and the yield of the products. Experimental data suggest that the brominating agent prepared in situ is molecular bromine and that LiBr assists the activation of H2O2 allowing bromination to occur using AcOH as a mild proton source in uncatalyzed experiments. Scale-up is feasible: 10.0 mmol of 1-octene was quantitatively converted to 1,2-dibromooctene in one hour of reaction at room temperature.
Copper-catalyzed regioselective allylic oxidation of olefins via C–H activation
Zhu, Nengbo,Qian, Bo,Xiong, Haigen,Bao, Hongli
supporting information, p. 4125 - 4128 (2017/09/29)
A regioselective oxidation of allylic C–H bond to C–O bond catalyzed by copper (I) was developed with diacyl peroxides as oxidants. The oxidation of allylic C–H bond was accomplished with good yield and regioselectivity under mild reaction conditions. This method has a broad substrate scope including cyclic olefins, terminal and internal acyclic olefins and allyl benzene compounds. The reaction proceeds by a radical mechanism as suggested by spin trapping experiments.
