39124-46-4Relevant academic research and scientific papers
Manganese Catalyzed Enantioselective Epoxidation of α,β-Unsaturated Amides with H2O2
Ottenbacher, Roman V.,Kurganskiy, Vladimir I.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
supporting information, p. 2778 - 2782 (2021/04/29)
Herewith, we report the enantioselective epoxidation of electron-deficient cis- and trans-α,β-unsaturated amides with the environmentally benign oxidant H2O2. The catalysts - manganese complexes with bis-amino-bis-pyridine and structurally related ligands - exhibit reasonably high efficiency (up to 100 TON) and excellent chemo- and enantioselectivity (up to 100% and 99% ee, respectively). Crucially, the cis-enamides epoxidation enantioselectivity and yield are dramatically enhanced by the presence of NH-moiety, which effect can be explained by the hydrogen bonding interaction between the cis-enamide substrate and the manganese based oxygen transferring species. (Figure presented.).
Energy-Transfer-Mediated Photocatalysis by a Bioinspired Organic Perylenephotosensitizer HiBRCP
Zhang, Yan,Xia, Mingze,Li, Min,Ping, Qian,Yuan, Zhenbo,Liu, Xuanzhong,Yin, Huimin,Huang, Shuping,Rao, Yijian
, p. 15284 - 15297 (2021/11/01)
Energy transfer plays a special role in photocatalysis by utilizing the potential energy of the excited state through indirect excitation, in which a photosensitizer determines the thermodynamic feasibility of the reaction. Bioinspired by the energy-transfer ability of natural product cercosporin, here we developed a green and highly efficient organic photosensitizer HiBRCP (hexaisobutyryl reduced cercosporin) through structural modification of cercosporin. After structural manipulation, its triplet energy was greatly improved, and then, it could markedly promote the efficient geometrical isomerization of alkenes from the E-isomer to the Z-isomer. Moreover, it was also effective for energy-transfer-mediated organometallic catalysis, which allowed realization of the cross-coupling of aryl bromides and carboxylic acids through efficient energy transfer from HiBRCP to nickel complexes. Thus, the study on the relationship between structural manipulation and their photophysical properties provided guidance for further modification of cercosporin, which could be applied to more meaningful and challenging energy-transfer reactions.
Contra-thermodynamic E → Z isomerization of cinnamamides via selective energy transfer catalysis
Becker, Marc R.,Morack, Tobias,Robertson, Jack,Metternich, Jan B.,Mück-Lichtenfeld, Christian,Daniliuc, Constantin,Burley, Glenn A.,Gilmour, Ryan
, (2020/05/25)
A bio-inspired, photocatalytic E → Z isomerization of cinnamides is reported using inexpensive (?)-riboflavin (vitamin B2) under irradiation at λ = 402 nm. This operationally simple transformation is compatible with a range of amide derivatives including –NR2, –NHSO2R and N(Boc)2 (up to 99:1 Z:E). Selective energy transfer from the excited state photocatalyst to the starting E-isomer ensures that directionality is achieved: The analogous process with the Z-isomer is inefficient due to developing allylic strain causing chromophore deconjugation. This is supported by X-ray analysis and Stern-Volmer photo-quenching studies. Preliminary validation of the method in manipulating the conformation of a simple model Leu-enkephalin penta-peptide is disclosed via the incorporation of a cinnamamide-based amino acid.
Photocatalyst-free visible light promoted: E → Z isomerization of alkenes
Xu, Jianbin,Liu, Na,Lv, Haiping,He, Chixian,Liu, Zining,Shen, Xianfu,Cheng, Feixiang,Fan, Baomin
supporting information, p. 2739 - 2743 (2020/06/17)
A simple and green method of visible light driven photocatalytic E to Z isomerization of alkenes has been developed. A variety of (Z)-alkenes can be prepared in the presence of visible light, without any additional photocatalyst. This protocol features photocatalyst-free conditions, which are mild, tolerant, and operationally simple, and is easy to implement.
Water as a Hydrogenating Agent: Stereodivergent Pd-Catalyzed Semihydrogenation of Alkynes
Zhao, Chuan-Qi,Chen, Yue-Gang,Qiu, Hui,Wei, Lei,Fang, Ping,Mei, Tian-Sheng
supporting information, p. 1412 - 1416 (2019/03/07)
Palladium-catalyzed transfer semihydrogenation of alkynes using H2O as the hydrogen source and Mn as the reducing reagent is developed, affording cis- and trans-alkenes selectively under mild conditions. In addition, this method provides an efficient way to access various cis-1,2-dideuterioalkenes and trans-1,2-dideuterioalkenes by using D2O instead of H2O.
Photocatalytic E → Z isomerization of polarized alkenes inspired by the visual cycle: Mechanistic dichotomy and origin of selectivity
Metternich, Jan B.,Artiukhin, Denis G.,Holland, Mareike C.,Von Bremen-Kuhne, Maximilian,Neugebauer, Johannes,Gilmour, Ryan
, p. 9955 - 9977 (2018/05/31)
Iteratively executed with exquisite spatial and temporal control, the selective isomerization of polarized alkenes underpins a plethora of complex biological processes ranging from natural product biosynthesis through to the mammalian visual cycle. However, nature's proficiency conceals the inherent difficulties in replicating this contrathermodynamic transformation in the laboratory. Recently, we disclosed the first highly Z-selective isomerization of polarized alkenes, employing the cinnamoyl chromophore as a retinal surrogate under UV-irradiation (402 nm) with (-)-riboflavin (Vitamin B2) as an inexpensive, organic photocatalyst (J. Am. Chem. Soc. 2015, 137, 11254-11257). This study was inspired by the propensity of crystalline (-)-riboflavin in the eyes of vertebrates to invert the intrinsic directionality of retinal isomerization. Herein, we extend this methodology to include a bioinspired, catalytic E → Z isomerization of α,β-unsaturated nitriles, thereby mimicking the intermediate Opsin-derived, protonated Schiff base in the visual cycle with simple polarized alkenes. Replacement of the iminium motif by a cyano group is well tolerated and gives an additional degree of versatility for postisomerization functionalization. Broad substrate scope is demonstrated (up to 99:1 Z:E) together with evidence of mechanistic dichotomy via both singlet and triplet energy transfer mechanisms. Kinetic studies, temperature dependent photostationary state correlations and investigation of substituent-based electronic perturbation of the alkene identified polarization combined with increased Z-isomer activation barriers as the selectivity governing factors in catalysis. This investigation demonstrates the importance of internal structural preorganization on photostationary composition and explicates the augmented Z-selectivity upon hydrogen-alkyl exchange at the β-position of the alkene.
Palladium chloride catalyzed photochemical Heck reaction
Waghmode, Suresh B.,Arbuj, Sudhir S.,Wani, Bina N.,Gopinath
supporting information, p. 348 - 351 (2013/06/04)
PdCl2 catalyzed carbon-carbon bond formation (Heck reaction) between substituted aryl halides and olefins was carried out without a ligand, under irradiation with UV-visible light. The results demonstrated that UV-visible light accelerated the rate of the reaction, leading to an excellent yield of corresponding products. The recovered palladium nanoparticles could be thermally recycled several times. PdCl2 gave excellent conversion up to the fifth addition of substrate.
Sunlight promoted palladium catalysed Mizoroki-Heck, Suzuki-Miyaura and Sonogashira reactions
Chaudhary, Anju R.,Bedekar, Ashutosh V.
, p. 6100 - 6103,4 (2020/08/20)
The palladium catalysed Mizoroki-Heck, Suzuki-Miyaura and Sonogashira reactions were successfully carried out under irradiation with sunlight. The Heck reaction gives considerable amount of Z product due to photochemical isomerization of initially formed E alkenes. Reaction of methyl 2-iodobenzoate with acrylamide under solar condition furnished 2H-2-benzazepine-1,3-dione rather than the expected derivative of cinnamate while the same reaction with ethyl 2-iodobenzoate gave the desired cinnamide.
Key structural features of cis-cinnamic acid as an allelochemical
Abe, Masato,Nishikawa, Keisuke,Okuda, Katsuhiro,Shindo, Mitsuru,Fukuda, Hiroshi,Nakanishi, Kazunari,Tazawa, Yuta,Taniguchi, Tomoya,Park, So-Young,Hiradate, Syuntaro,Fujii, Yoshiharu
, p. 56 - 67,12 (2012/12/12)
1-O-cis-cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the cis-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclohexene analogue showed strong activity. These results suggest that the geometry of the C-C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C-C double bond were also investigated.
Zinc-mediated facile synthesis of α,β-unsaturated primary amides
Feng, Sunlin,Zhang, Zhiying,Jiang, Shilei,Yu, Xiaochun
experimental part, p. 382 - 384 (2010/11/03)
A general method for the synthesis of α,β-unsaturated primary amides was achieved by an one-pot, triphenylphosphine-and zinc powder-promoted Wittig reaction of bromoacetamide and aldehydes under solvent-free conditions.
