36846-09-0Relevant articles and documents
Zirconium-redox-shuttled cross-electrophile coupling of aromatic and heteroaromatic halides
Fu, Yue,Liu, Fang-Jie,Liu, Peng,Tang, Jian-Tao,Toste, F. Dean,Wu, Ting-Feng,Ye, Baihua,Zhang, Yue-Jiao
supporting information, p. 1963 - 1974 (2021/07/07)
Transition metal-catalyzed cross-electrophile coupling (XEC) is a powerful tool for forging C(sp2)–C(sp2) bonds in biaryl molecules from abundant aromatic halides. While the synthesis of unsymmetrical biaryl compounds through multimetallic XEC is of high synthetic value, the selective XEC of two heteroaromatic halides remains elusive and challenging. Herein, we report a homogeneous XEC method, which relies on a zirconaaziridine complex as a shuttle for dual palladium-catalyzed processes. The zirconaaziridine-mediated palladium (ZAPd)-catalyzed reaction shows excellent compatibility with various functional groups and diverse heteroaromatic scaffolds. In accord with density functional theory (DFT) calculations, a redox transmetallation between the oxidative addition product and the zirconaaziridine is proposed as the crucial elementary step. Thus, cross-coupling selectivity using a single transition metal catalyst is controlled by the relative rate of oxidative addition of Pd(0) into the aromatic halide. Overall, the concept of a combined reducing and transmetallating agent offers opportunities for the development of transition metal reductive coupling catalysis.
Base-catalysed [3 + 2] cycloaddition of propargylamines and aldehydes to substituted furans
Shen, Jinhai,Zhao, Jing,Hu, Bing,Chen, Yangxin,Wu, Longqiao,You, Qihua,Zhao, Li
, p. 600 - 603 (2018/02/14)
A base-catalysed [3 + 2] cycloaddition reaction of propargylamines and aldehydes for the regiospecific synthesis of substituted furans under metal-free conditions is developed. Propargylamines are used as allenyl anion equivalents and applied in [3 + 2] cycloaddition reactions with aldehydes. Various substituted furans are provided up to 91% yield for 28 examples.
Modular Synthesis of Multisubstituted Furans through Palladium-Catalyzed Three-Component Condensation of Alkynylbenziodoxoles, Carboxylic Acids, and Imines
Wu, Junliang,Yoshikai, Naohiko
supporting information, p. 11107 - 11111 (2016/07/06)
Mild and regiocontrolled synthesis of a multisubstituted furan is achieved through Pd(OAc)2-catalyzed room-temperature condensation of an alkynylbenziodoxole, a carboxylic acid, and an enolizable ketimine, which contribute to C1, CO, and C2 fragments, respectively, to the furan skeleton. The reaction tolerates a broad range of functional groups in each of the reaction components, and enables highly modular and flexible synthesis of variously substituted furans. The reaction is particularly effective for the rapid generation of tri- and tetraarylfurans and furan-containing oligoarylenes without relying on conventional cross-coupling chemistry.
Palladium-catalyzed condensation of N -aryl imines and alkynylbenziodoxolones to form multisubstituted furans
Lu, Beili,Wu, Junliang,Yoshikai, Naohiko
supporting information, p. 11598 - 11601 (2014/10/16)
A palladium(II) catalyst promotes condensation of an N-aryl imine and an alkynylbenziodoxolone derivative to afford a multisubstituted furan, whose substituents are derived from the alkynyl moiety (2-position), the imine (3- and 4-positions), and the 2-iodobenzoate moiety (5-position), along with an N-arylformamide under mild conditions. The 2-iodophenyl group of the furan product serves as a versatile handle for further transformations. A series of isotope-labeling experiments shed light on the bond reorganization process in this unusual condensation reaction, which includes cleavage of the C-C triple bond and fragmentation of the carboxylate moiety.
Oxidative cross-coupling of allenyl ketones and organoboronic acids: Expeditious synthesis of highly substituted furans
Xia, Ying,Xia, Yamu,Ge, Rui,Liu, Zhen,Xiao, Qing,Zhang, Yan,Wang, Jianbo
supporting information, p. 3917 - 3921 (2014/05/06)
Allenyl ketones are employed as coupling partners in palladium-catalyzed oxidative cross-coupling reactions with organoboronic acids. This reaction constitutes an efficient methodology for the synthesis of highly substituted furan derivatives. Palladium-carbene migratory insertion is proposed as the key step in this transformation. Migration patterns: Allenyl ketones are employed as a coupling partner in a palladium-catalyzed oxidative cross-coupling reaction with organoboronic acids. This reaction constitutes an efficient methodology for the synthesis of highly substituted furan derivatives. Palladium-carbene migratory insertion is proposed as the key step in this transformation. BQ=1,4-benzoquinone.
A facile approach to highly functional trisubstituted furans via intramolecular Wittig reactions
Chen, Ko-Wei,Syu, Siang-En,Jang, Yeong-Jiunn,Lin, Wenwei
supporting information; experimental part, p. 2098 - 2106 (2011/05/08)
An efficient and mild synthesis of trisubstituted furans, starting from α,β-unsaturated ketones, tributylphosphine, and acyl chlorides, is described. The strategy employs the intramolecular Wittig protocol as a key step to install the crucial furan ring,
Photochemical and Thermal Transformations of 3-Benzyl-2(3H)-furanones and Related Substrates
Gopidas, K. R.,Cyr, D. R.,Das, P. K.,George, M. V.
, p. 5505 - 5511 (2007/10/02)
Photochemical and thermal transformations of several 2(3H)-furanones are reported.Steady-state irradiations of 3-benzyl-3,5-diphenyl-2(3H)-furanone (1a) in benzene or methanol, for example, gave a mixture of 2,3,5-triphenylfuran (3a) (8-9percent) and 1,3,5-triphenylbut-3-en-1-one (6a) (26-34percent), along with 34-37percent recovery of the unchanged starting material.Similar results were obtained with 3-benzyl-3-(4-methylphenyl)-5-phenyl-2-(3H)-furanone (1b) and 3-benzyl-3-(4-methoxyphenyl)-5-phenyl-2(3H)-furanone (1c) under analogous conditions.Upon direct irradiation, 3,3-dibenzyl-5-phenyl-2(3H)-furanone (1d), however, gave only 3-benzyl-1,4-diphenylbut-3-en-1-one (6d) (80-83percent), whereas 3-benzyl-3-phenylphenanthrofuran-2(3H)-one (1e) gave only 2,3-diphenylphenanthrofuran (3e) (15-21percent).On the other hand, 3-benzoyl-3,5-diphenyl-2(3H)-furanone (1f) gave only the bis lactone 10a (72-75percent) under direct photolysis.The bis lactones 10a-c and the rearranged 5-benzyl-3,5-diaryl-2(5H)-furanones 9a-d were the major products in the course of sensitized irradiation of 1a-d in the presence of acetophenone in benzene.The thermolysis of 1a-d also led to the formation of the rearrangement products 9a-d in high yields (60-80percent).Possible mechanisms of these various photochemical and thermal reactions are discussed in terms of singlet-mediated decarbonylation, triplet-sensitized homolysis of the benzyl-to-furanone bond and probable thermal -sigmatropic shift of the benzyl group.The laser pulse photoexcitation (337.1 nm) of benzophenone in the presence of 1a-d in benzene of acetonitrile produces the short-lived triplets of the 2(3H)-furanones (τT = 0.5-3.0 μs), which subsequently undergo bond cleavage lea ding to furanoxy radicals.The spectral and kinetic features of the triplets and the radicals are presented.
