Alkyl–Aryl Coupling Catalyzed by Tandem Systems of Pincer-Ligated Iridium Complexes and Zeolites
† Department
of Chemistry and Chemical Biology, Rutgers,
The State University of New Jersey, New Brunswick, New Jersey 08903, United States
‡ Department
of Chemistry, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam India
§ Chevron Energy
Technology
Company, 100 Chevron Way, Richmond, California 94802, United States
⊥ Department
of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, United States
ACS Catal., 2016, 6, pp 2836–2841
DOI: 10.1021/acscatal.6b00149
Publication Date (Web): March 28, 2016
Copyright © 2016 American Chemical Society
We report that pincer-ligated iridium catalysts for alkane
dehydrogenation can operate in tandem with zeolite catalysts for
arene–alkene coupling, to effect the overall intramolecular
dehydrocoupling of alkyl–H and aryl–H bonds (i.e., the
dehydrocyclization of alkyl benzene). Thus, zeolite and soluble iridium
cocatalysts in refluxing pentylbenzene (205 °C) gave high yields of
1-methyl-1,2,3,4-tetrahydronaphthalene. Subsequent dehydrogenation and
isomerization affords 1- and 2-methylnaphthalene and
2-methyl-1,2,3,4-tetrahydronaphthalene. Total yields of cyclized product
as high as 5.4 M (94%) have been obtained, corresponding to 6800
turnovers per mol Ir. Turnover numbers for the tandem-catalyzed
dehydrocyclization are much greater than those obtained for simple
dehydrogenation by Ir catalysts (to give olefins) in the absence of
zeolite.
