848863-57-0Relevant 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.
Trifluoromethyl groups in crystal design of 1,4-diphenyl-1,3-butadienes for topochemical [2 + 2] photodimerization
Liu, Jin,Wendt, Natalie L.,Boarman, Kelly J.
, p. 1007 - 1010 (2007/10/03)
(Figure Presented) UV irradiation of the powdered crystalline sample of each of three (E,E)-1,4-di(trifluoromethyl-substituted)phenyl-1,3-butadienes (1-3) was found to yield a single [2 + 2] cycloaddition product in the solid state. Moreover, upon irradia
