56693-03-9Relevant academic research and scientific papers
Catalytic Dehydrogenative C-C Coupling by a Pincer-Ligated Iridium Complex
Wilklow-Marnell, Miles,Li, Bo,Zhou, Tian,Krogh-Jespersen, Karsten,Brennessel, William W.,Emge, Thomas J.,Goldman, Alan S.,Jones, William D.
supporting information, p. 8977 - 8989 (2017/07/12)
The pincer-iridium fragment (iPrPCP)Ir (RPCP = ?3-2,6-C6H3(CH2PR2)2) has been found to catalyze the dehydrogenative coupling of vinyl arenes to afford predominantly (E,E)-1,4-diaryl-1,3-butadienes. The eliminated hydrogen can undergo addition to another molecule of vinyl arene, resulting in an overall disproportionation reaction with 1 equiv of ethyl arene formed for each equivalent of diarylbutadiene produced. Alternatively, sacrificial hydrogen acceptors (e.g., tert-butylethylene) can be added to the solution for this purpose. Diarylbutadienes are isolated in moderate to good yields, up to ca. 90% based on the disproportionation reaction. The results of DFT calculations and experiments with substituted styrenes indicate that the coupling proceeds via double C-H addition of a styrene molecule, at β-vinyl and ortho-aryl positions, to give an iridium(III) metalloindene intermediate; this intermediate then adds a β-vinyl C-H bond of a second styrene molecule before reductively eliminating product. Several metalloindene complexes have been isolated and crystallographically characterized. In accord with the proposed mechanism, substitution at the ortho-aryl positions of the styrene precludes dehydrogenative homocoupling. In the case of 2,4,6-trimethylstyrene, dehydrogenative coupling of β-vinyl and ortho-methyl C-H bonds affords dimethylindene, demonstrating that the dehydrogenative coupling is not limited to C(sp2)-H bonds.
Total Syntheses of the Isomeric Aglain Natural Products Foveoglin A and Perviridisin B: Selective Excited-State Intramolecular Proton-Transfer Photocycloaddition
Wang, Wenyu,Clay, Anthony,Krishnan, Retheesh,Lajkiewicz, Neil J.,Brown, Lauren E.,Sivaguru, Jayaraman,Porco, John A.
, p. 14479 - 14482 (2017/10/20)
Selective excited-state intramolecular proton-transfer (ESIPT) photocycloaddition of 3-hydroxyflavones with trans, trans-1,4-diphenyl-1,3-butadiene is described. Using this methodology, total syntheses of the natural products (±)-foveoglin A and (±)-perviridisin B were accomplished. Enantioselective ESIPT photocycloaddition using TADDOLs as chiral hydrogen-bonding additives provided access to (+)-foveoglin A. Mechanistic studies have revealed the possibility for a photoinduced electron-transfer (PET) pathway.
Rh2(OAc)4-catalyzed formation of trans-alkenes from the reaction of aldehydes with perfluorophenyl diazomethane through tellurium ylide
Zhu, Shifa,Xing, Chunhui,Pang, Wan,Zhu, Shizheng
, p. 5897 - 5900 (2007/10/03)
Rh2(OAc)4 can catalyze the formation of perfluorophenyl-containing trans-epoxides from the reactions of perfluorophenyl diazomethane with activated aryl aldehydes through sulfur ylide intermediate. In contrast, under the same reactio
Regiospecific photoisomerization of fluorinated (E,E)-1,4-diphenyl-1,3- butadienes
Liu, Jin,Boarman, Kelly J.,Wendt, Natalie L.,Cardenas, Lina M.
, p. 4953 - 4956 (2007/10/03)
Photoisomerization of five fluorinated E,E-1-(R-phenyl)-4-phenyl-1,3- butadienes in solution (R = 1: p-monofluoro, 2: m,m′-difluoro, 3: m,m′,p-trifluoro, 4: o,o′,m,m′-tetrafluoro, 5: o,o′,m,m′,p-pentafluoro) was investigated via direct irradiation. Our results indicated that cis-trans photoisomerization of the fluorinated 1,4-diphenyl-1,3-butadienes in the excited singlet state took place exclusively at the CC bonds closer to the fluorine substituents.
Transition-Metal-Catalyzed Formation of trans Alkenes via Coupling of Aldehydes
Zhu, Shifa,Liao, Yuanxi,Zhu, Shizheng
, p. 377 - 380 (2007/10/03)
(Equation presented) Rh2(OAc)4 catalyzed the formation of exclusively trans fluorinated alkenes from aldehydes and pentafluorobenzaldehyde tosylhydrazone salts, which were readily prepared from pentafluorobenzaldehyde using the Bamfo
