Illuminating the unexpected benzylic carbon-carbon bond cleavage of arylated ethanes with Di-n-butylzirconium diethoxide by illumination: Transfer epizirconation as exclusively a photochemical process

Organometallics

Volumn 26, Issue 4, 2007, Pages 778-779

  Eisch, John J ^a   Gitua, John N ^b  

^a BINGHAMTON UNIVERSITY   (United States)

^b DRAKE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

DI-N-BUTYLZIRCONIUM DIETHOXIDE; PHOTOCHEMICAL PROCESS;

BINDING ENERGY; CATALYSIS; CHEMICAL BONDS; IRON COMPOUNDS; LIGHTING; PHOTOCHEMICAL REACTIONS; SYNTHESIS (CHEMICAL);

ETHANE;

EID: 33847246873     PISSN: 02767333     EISSN: None     Source Type: Journal    
DOI: 10.1021/om061009y     Document Type: Article

References (22)

1. Organic Chemistry of Subvalent Transition Metal Complexes. 41. Part 40: Eisch, J. J.; Qian, Y. Rheingold, A. L. Eur. J. Inorg. Chem., in press.
2. Eisch, J. J.; Gitua, J. N. Organometallics 2003, 22, 24.
3. Eisch, J. J.; Gitua, J. N. Organometallics 2003, 22, 4172.
4. Eisch, J. J.; Otieno, P. O. Eur. J. Org. Chem. 2004, 3269.
5. Eisch, J. J.; Gitua, J. N. U.S. Patent 6,743,872, June 1, 2004.
6. Eisch, J. J.; Adeosun, A. A. Eur. J. Org. Chem. 2005, 993.
7. Eisch, J. J.; Adeosun, A. A.; Dutta, S.; Fregene, P. O. Eur. J. Org. Chem. 2005, 2657.
8. Eisch, J. J.; Owuor, F. A.; Shi, X. Polyhedron 2005, 24, 1325 (Symposium-in-Print).
9. Eisch, J. J.; Otieno, P. O.; Gitua, J. N.; Adeosun, A. A. Eur. J. Org. Chem. 2005, 4364.
10. (a) Eisch, J. J.; Dutta, S. Organometallics 2004, 23, 4181.
11. 4 and 2 BuLi and thus having LiCl as a byproduct, is unable to cause such zirconations.
12. Eisch, J. J.; Dutta, S. Organometallics 2005, 24, 3355.
13. (a) Eisch, J. J.; Dutta, S. Gitua, J. N. Organometallics 2005, 24, 6291.
14. 2O: only α-deuteriodiphenyl-methane was produced.
15. For the seminal publication on alkane metathesis through the use of zirconium hydrides bonded on silica for the hydrogenolysis of simple alkanes at mild temperatures (150°C), cf.: Corker, J.; Lefebvre, F.; Lecuyer, C.; Dufaud, V.; Quignard, F.; Choplin, A.; Evans, J.; Basset, J. M. Science 1996, 271, 966.
16. Upon completion of his doctoral studies, our fellow co-author, Dr. Somnath Dutta, had accepted a teaching position, where his teaching duties and available laboratory facilities have not permitted him to collaborate with us in unraveling this surprising instance of apparent reproducibility.
17. Dutta, S. Alkylzirconium Alkoxides in Organic Synthesis: Reactions with sigma- and pi-Bonded Organic Substrates. Doctoral Dissertation, State University of New York at Binghamton, 2005; 209 pp.
18. The laboratory bench on which Dr. Dutta's original cleavage reactions were performed had directly overhead and parallel to the bench a line of fluorescent light fixtures, each of which contained a 32-watt light tube. The separation of the reaction flask and the overhead light was 1.5 m. The laboratory bench on which we conducted our repetition of such cleavages had a similar line of fluorescent lights running at right angles to the bench that were not directly over the reaction flask. Here the separation of flask and fixture was 2.80 m. Clearly, Dr. Dutta's apparatus was better positioned to benefit from the ambient light necessary for the photopromotion.
19. (a) Since such photoreactions were found to occur in reaction vessels of Pyrex glass, the wavelength of the exciting irradiation must have been >300 nm, since such glass is not transparent to wavelengths <300 nm.
20. (b) The impetus to test for the possible catalytic activity of iron(III) salts came from our speculation before we discovered the photoeffect that iron salts could have adventitiously been generated in the reaction medium through the leaching of iron from the Teflon-coated but corroded magnet stirring bar. Such bars are made of ALNICO-V alloys, composed of 51 % Fe (with trace impurities), 24% Co, 14% Ni, 8% Al, and 3% Cu.
21. The extreme thermal stability of the C-C bond in 6 to dissociation or oxidation is vividly illustrated by the distillation of this hydrocarbon in air under reduced pressure at 280°C without decomposition. Cf.: Bachmann, W. E. In Organic Chemistry-An Advanced Treatise, 2nd ed.; Oilman, H., Ed.; Wiley: New York, 1943; Vol. 1, p 604.
22. 1H NMR data are in accord with the expected empirical structure, but profound changes occur in such spectra at higher temperatures.