2757-04-2Relevant academic research and scientific papers
Heteroleptic copper(I) complexes as energy transfer photocatalysts for the intermolecular [2 + 2] photodimerization of chalcones, cinnamates and cinnamamides
Wu, Qing-An,Ren, Chen-Chao,Chen, Feng,Wang, Tian-Qi,Zhang, Yu,Liu, Xue-Fen,Chen, Jian-Bin,Luo, Shu-Ping
supporting information, (2021/05/10)
The [2 + 2] photodimerization of chalcones, cinnamates and cinnamamides can be effectively catalyzed by heteroleptic copper(I) complexes. The reactions were carried out under mild reaction conditions and the products were obtained in 20–72% yield under visible light irradiation. The copper-based photocatalyst comprised of the rigid phenanthroline ligand with substituents at the 2,9-positions and the 4,7-positions showed high activity in the photodimerization via an energy transfer pathway.
Microwave accelerated the solvent-free synthesis of 4-aryl-3,4-dihydrocoumarin via the tandem reaction of cinnamic acids with phenols catalyzed by Amberlyst 15 resin
Le, Huu-Phuoc,Duong, Cong-Thang,Nguyen, Xuan-Triet,Luu, Thi Xuan Thi
, p. 2187 - 2203 (2021/07/02)
Amberlyst 15 resin supported the tandem reaction of cinnamic acids with phenols under solvent-free reaction condition has been introduced to afford 4-aryl-3,4-dihydrocoumarin (neoflavanone) derivatives. The efficiency of solid acidic sulfonic resin (A-15) has been illustrated in two reaction activation methods such as microwave irradiation and conventional heating. The important roles of Amberlyst 15 have been emphasized strongly through the high yields of 4-aryl-3,4-dihydrocoumarin in the shorter time under the assistance of microwave irradiation than of conventional heating, and its high recovery and reusability for six catalyst runs. The original catalyst as well as the recycled catalyst were characterized by XRD and FE-SEM to study the correlation of the surface of reused catalyst and its recyclability.
Hypervalent iodine(iii) induced oxidative olefination of benzylamines using Wittig reagents
Ramavath, Vijayalakshmi,Rupanawar, Bapurao D.,More, Satish G.,Bansode, Ajay H.,Suryavanshi, Gurunath
, p. 8806 - 8813 (2021/05/26)
We have developed hypervalent iodine(iii) induced oxidative olefination of primary and secondary benzylamines using 2C-Wittig reagents, which provides easy access to α,β-unsaturated esters. Mild reaction conditions, good to excellent yields with high (E) selectivity, and a broad substrate scope are the key features of this reaction. We have successfully carried out the gram-scale synthesis of α,β-unsaturated esters.
Mizoroki-Heck Reaction of Unstrained Aryl Ketones via Ligand-Promoted C-C Bond Olefination
Wang, Mei-Ling,Xu, Hui,Li, Han-Yuan,Ma, Biao,Wang, Zhen-Yu,Wang, Xing,Dai, Hui-Xiong
, p. 2147 - 2152 (2021/04/05)
Mizoroki-Heck reaction of unstrained aryl ketone with acrylate/styrene is accomplished via palladium-catalyzed ligand-promoted C-C bond cleavage. Various (hetero)aryl ketones are compatible in the reaction, affording the alkene product in good to excellent yields. Further applications in the late-stage olefination of some drugs, natural products, and fragrance-derived aryl ketones demonstrate the synthetic utility of this protocol. By employing ketone as both the directing group and the leaving group, 1,2-bifunctionalization is achieved via sequential ortho-C-H alkylation/ipso-Heck olefination.
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.
Photoinduced Oxidative Alkoxycarbonylation of Alkenes with Alkyl Formates
Tang, Wan-Ying,Chen, Ling,Zheng, Ming,Zhan, Le-Wu,Hou, Jing,Li, Bin-Dong
supporting information, p. 3939 - 3943 (2021/05/26)
A photoinduced oxidative alkoxycarbonylation of alkenes initiated by intermolecular addition of alkoxycarbonyl radicals has been demonstrated. Employing alkyl formates as alkoxycarbonyl radical sources, a range of α,β-unsaturated esters were obtained with good regioselectivity and E selectivity under ambient conditions.
Fluoride anion-initiated bis-trifluoromethylation of phenyl aromatic carboxylates with (trifluoromethyl)trimethylsilane
Takahashi, Kenjiro,Ano, Yusuke,Chatani, Naoto
supporting information, p. 11661 - 11664 (2020/10/19)
The fluoride anion-initiated reaction of phenyl aromatic carboxylates with (trifluoromethyl)trimethylsilane (Me3SiCF3) that results in the formation of O-silyl-protected 2-aryl-1,1,1,3,3,3-hexafluoroisopropanols is reported. A phenoxide anion, generated during the trifluoromethylation of the phenyl carboxylate, also activates the Me3SiCF3, which permits a catalytic amount of the fluoride anion source to be used. Various functional groups, which can be used for further elaboration, are tolerated in the reaction.
Enantioselective Synthesis of 3,4-Dihydropyran-2-ones via Phase-Transfer-Catalyzed Addition-Cyclization of Acetylacetone to Cinnamic Thioesters
Destro, Dario,Bottinelli, Carlo,Ferrari, Ludovica,Albanese, Domenico C. M.,Bencivenni, Grazia,Gillick-Healy, Malachi W.,Kelly, Brian G.,Adamo, Mauro F. A.
supporting information, p. 5183 - 5192 (2020/04/10)
Herein, we present the first example of synthesis of 3,4-dihydropyran-2-ones from cinnamic thioesters via a stereoselective phase-transfer-catalyzed domino Michael-cyclization reaction with acetylacetone. The reaction proceeded under the catalysis of Cinchona-derived quaternary ammonium phenoxide that, in combination with inorganic bases, provided 3,4-dihydropyran-2-ones in yields of up to 93% and enantioselectivities of up to 88% enantiomeric excess.
Donor-acceptor fluorophores as efficient energy transfer photocatalysts for [2 + 2] photodimerization
Chen, Feng,Chen, Hao,Liu, Xue-Fen,Luo, Shu-Ping,Ren, Chen-Chao,Wu, Qing-An,Xu, Liang-Xuan,Yu, Xiao-Cong
, p. 3707 - 3716 (2020/06/03)
Mild [2 + 2] photodimerization of enone substrates was induced by donor-acceptor fluorophores. Enone substrates were activated efficiently for anti-head to head dimerizations with a high yield (up to 83%) and high selectivity. The adjustable excited state potential also allows donor-acceptor fluorophores to be used for isomerization of the above substrates, confirming the potential of donor-acceptor fluorophores as energy transfer photocatalysts.
Pd-catalyzed oxidative Heck-type arylation of vinyl ketones, alkenes, and acrylates with Sb-aryl-tetrahydrodibenz[c,f][1,5]azastibocines
Murata, Yuki,Kakusawa, Naoki,Arakawa, Yukako,Hayashi, Yukako,Morinaga, Shun,Ueda, Masaaki,Hyodo, Tadashi,Matsumura, Mio,Yamaguchi, Kentaro,Kurita, Jyoji,Yasuike, Shuji
, (2020/10/18)
The Pd-catalyzed cross-coupling reactions of Sb-aryl-1,5-azastibocines with alkenes are described. The reactions of azastibocines with alkenes such as vinyl ketones, alkenes, and acrylates in the presence of 10 mol% PdCl2 at 80 °C in DMA under aerobic conditions produced Heck adducts in moderate-to-excellent yields. Single-crystal X-ray and NMR analysis revealed that the aryl donors in this reaction, the Sb-aryl-1,5-azastibocines, are hypervalent compounds that display N–Sb intramolecular non-bonding interaction. These are the first examples of Pd-catalyzed Heck-type arylations using heterocyclic hypervalent organoantimony compounds. Although the reactions proceeded efficiently with the azastibocines, they hardly progressed with trivalent and pentavalent triarylantimony reagents.
