1539-59-9Relevant articles and documents
USY-zeolite catalyzed synthesis of 1,4-dihydropyridines under microwave irradiation: structure and recycling of the catalyst
Alponti, Leonardo H.R.,Picinini, Monize,Urquieta-Gonzalez, Ernesto A.,Corrêa, Arlene G.
, (2020/10/20)
The Hantzsch three-component reaction is the best-known multicomponent reaction, affording dihydropyridines which have been employed therapeutically and also as visible‐light photoredox catalysts. In this work we report the application of an ultra-stable
Manganese-Mediated Direct Functionalization of Hantzsch Esters with Alkyl Iodides via an Aromatization-Dearomatization Strategy
Liu, Xian-Guan,Dong, Ci-Shuang,Li, Fei,Zhang, Bo
supporting information, p. 4002 - 4007 (2021/05/26)
We report, for the first time, manganese-mediated direct functionalization of the Hantzsch esters with readily accessible alkyl iodides through an aromatization-dearomatization strategy. Applying this protocol, a library of valuable 4-alkyl-1,4-dihydropyridines were facilely afforded in good yields. This simple and practical reaction proceeds under visible-light irradiation at room temperature and displays high functional-group compatibility. Additionally, the method is applicable for gram-scale synthesis and late-stage functionalization of complex molecules.
Visible-light-mediated alkylation of 4-alkyl-1,4-dihydropyridines with alkenyl sulfones
Dong, Jianyang,Liu, Yuxiu,Wang, Qingmin,Yue, Fuyang
supporting information, p. 8924 - 8928 (2021/11/04)
Herein we report a mild, general protocol for visible-light-mediated alkylation of 4-alkyl-1,4-dihydropyridines with alkenyl sulfones. The protocol permits efficient functionalization of sulfones with a broad range of cyclic and acyclic secondary and tert
Enantioselective Alkylamination of Unactivated Alkenes under Copper Catalysis
Bai, Zibo,Zhang, Heng,Wang, Hao,Yu, Hanrui,Chen, Gong,He, Gang
supporting information, p. 1195 - 1202 (2021/02/05)
An enantioselective addition reaction of various alkyl groups to unactivated internal alkenes under Cu catalysis has been developed. The reaction uses amide-linked aminoquinoline as the directing group, 4-alkyl Hantzsch esters as the donor of alkyl radicals, and rarely used biaryl diphosphine oxide as a chiral ligand. β-lactams featuring two contiguous stereocenters at Cβ and the β substituent can be obtained in good yield with excellent enantioselectivity. Mechanistic studies indicate that a nucleophilic addition of the alkyl radical to CuII-coordinated alkene is the enantio-determining step.
Catalyst-Free Decarbonylative Trifluoromethylthiolation Enabled by Electron Donor-Acceptor Complex Photoactivation
Lipp, Alexander,Badir, Shorouk O.,Dykstra, Ryan,Gutierrez, Osvaldo,Molander, Gary A.
supporting information, p. 3507 - 3520 (2021/06/11)
A catalyst- and additive-free decarbonylative trifluoromethylthiolation of aldehyde feedstocks has been developed. This operationally simple, scalable, and open-to-air transformation is driven by the selective photoexcitation of electron donor-acceptor (EDA) complexes, stemming from the association of 1,4-dihydropyridines (donor) with N-(trifluoromethylthio)phthalimide (acceptor), to trigger intermolecular single-electron transfer events under ambient- and visible light-promoted conditions. Extension to other electron acceptors enables the synthesis of thiocyanates and thioesters, as well as the difunctionalization of [1.1.1]propellane. The mechanistic intricacies of this photochemical paradigm are elucidated through a combination of experimental efforts and high-level quantum mechanical calculations [dispersion-corrected (U)DFT, DLPNO-CCSD(T), and TD-DFT]. This comprehensive study highlights the necessity for EDA complexation for efficient alkyl radical generation. Computation of subsequent ground state pathways reveals that SH2 addition of the alkyl radical to the intermediate radical EDA complex is extremely exergonic and results in a charge transfer event from the dihydropyridine donor to the N-(trifluoromethylthio)phthalimide acceptor of the EDA complex. Experimental and computational results further suggest that product formation also occurs via SH2 reaction of alkyl radicals with 1,2-bis(trifluoromethyl)disulfane, generated in-situ through combination of thiyl radicals. (Figure presented.).
One-pot multicomponent green Hantzsch synthesis of 1,2-dihydropyridine derivatives with antiproliferative activity
Bosica, Giovanna,Demanuele, Kaylie,Padrón, José M.,Puerta, Adrián
, p. 2862 - 2869 (2020/12/22)
A rapid route for obtaining unsymmetrical 1,2-dihydropyridines (1,2-DHPs) as opposed to 1,4-dihydropyridines (1,4-DHPs) has been achieved via a one-pot multicomponent Hantzsch reaction. A benign protocol has been developed for the preparation of various 1
A photocatalyst-free photo-induced denitroalkylation of β-nitrostyrenes with 4-alkyl substituted Hantzsch esters at room temperature
Duan, Chunying,Hao, Xinyu,Jin, Kun,Li, Yaming,Wang, Jiaao,Zhang, Rong,Zhang, Siyu
supporting information, (2020/02/18)
A photocatalyst-free stereoselectively photo-induced strategy for the denitroalkylation of β-nitrostyrenes using 4-alkyl substituted Hantzsch esters as the alkyl source under xenon lamp irradiation is developed. The reaction proceeds at room temperature and affords the corresponding products in moderate to excellent yields. The oxidant di-t-butyl peroxide serves as an efficient radical initiator under irradiation of a Xenon lamp, initiating alkyl radicals from the 4-alkyl substituted Hantzsch esters.
Visible-light-mediated minisci C-H alkylation of heteroarenes with 4-alkyl-1,4-dihydropyridines using O2as an oxidant
Dong, Jianyang,Liu, Yuxiu,Song, Hongjian,Wang, Qingmin,Xu, Wentao,Yue, Fuyang
supporting information, p. 5599 - 5604 (2020/09/21)
Herein, we report a protocol for direct visible-light-mediated Minisci C-H alkylation reactions of N-heteroarenes with 4-alkyl-1,4-dihydropyridines at room temperature with molecular oxygen as an oxidant. The protocol permits efficient functionalization of various N-heteroarenes with a broad range of cyclic and acyclic primary, secondary, and tertiary alkyl groups and is scalable to the gram level. This mild protocol uses an inexpensive, green oxidant and is suitable for late-stage C-H alkylation of complex nitrogen-containing molecules. We demonstrated its utility by preparing or functionalizing several pharmaceuticals and natural products.
Intermolecular Radical Addition to Ketoacids Enabled by Boron Activation
Xie, Shasha,Li, Defang,Huang, Hanchu,Zhang, Fuyuan,Chen, Yiyun
supporting information, p. 16237 - 16242 (2019/10/14)
The intermolecular radical addition to the carbonyl group is difficult due to the facile fragmentation of the resulting alkoxyl radical. To date, the intermolecular radical addition to ketones, a valuable approach to construct quaternary carbon centers, remains a formidable synthetic challenge. Here, we report the first visible-light-induced intermolecular alkyl boronic acid addition to α-ketoacids enabled by the Lewis acid activation. The in situ boron complex formation is confirmed by various spectroscopic measurements and mechanistic probing experiments, which facilitates various alkyl boronic acid addition to the carbonyl group and prevents the cleavage of the newly formed C-C bond. Diversely substituted lactates can be synthesized from readily available alkyl boronic acids and ketoacids at room temperature merely under visible light irradiation, without any additional reagent. This boron activation approach can be extended to alkyl dihydropyridines as radical precursors with external boron reagents for primary, secondary, and tertiary alkyl radical additions. The pharmaceutically useful anticholinergic precursors are easily scaled up in multigrams under metal-free conditions in flow reactors.
Radical alkylation of: Para -quinone methides with 4-substituted Hantzsch esters/nitriles via organic photoredox catalysis
Wu, Qing-Yan,Min, Qing-Qiang,Ao, Gui-Zhen,Liu, Feng
supporting information, p. 6391 - 6394 (2018/09/25)
A novel photocatalytic protocol is herein described for the preparation of functionalized phenols via radical alkylation of para-quinone methides under transition-metal-free conditions. The reaction is external oxidant free and performed at ambient temperature upon visible light irradiation, allowing the access to various desired products in satisfactory yields. The readily available 4-alkyl-1,4-dihydropyridines serve as the effective alkyl radical precursors.
