ORGANIC
LETTERS
2011
Vol. 13, No. 23
6308–6311
Palladium-Catalyzed CꢀC Bond Formation
of Arylhydrazines with Olefins via
CarbonꢀNitrogen Bond Cleavage
Ming-Kui Zhu, Jun-Feng Zhao, and Teck-Peng Loh*
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore 637371
Received October 24, 2011
ABSTRACT
The unactivated carbonꢀnitrogen bond of various aryl hydrazines was cleaved under very mild conditions by Pd(0) with the assistance of Pd(II).
The in situ generated aryl palladium complex readily takes part in the CꢀC bond formation with olefins. This study offered a new mode of CꢀPd
bond formation, which will spur the development of palladium-catalyzed cross-coupling in the future.
Palladium-catalyzed cross-coupling reactions via selective
cleavage of unreactive bonds such as carbonꢀhydrogen,1
carbonꢀcarbon,2 and carbonꢀnitrogen3 bonds are versatile
and powerful tools for organic chemists because they pro-
vide unique organic transformations which are difficult to
be carried out using other methods. Among these strategies,
the cross-coupling reaction involving carbonꢀnitrogen
bond cleavage is the least explored, especially for the non-
reactive carbonꢀnitrogen bond.3 Generally, the carbonꢀ
nitrogen bonds are activated by conversion to diazonium
salts,3aꢀc ammonium salt,3dꢀf or aza heterocycles.3g,h How-
ever, existing methods are still plagued with problems such
as limited substrate scope, harsh reaction conditions, the
explosive and unstable nature of the substrates, the need to
use strong acids and an air-sensitive nickel catalyst, etc. In
view of this, there is still a need to develop new methods
to cleave carbonꢀnitrogen bonds. Recently, Kakiuchi and
co-workers developed a carbonꢀcarbon bond formation
strategy via the ruthenium-catalyzed unactivated carbonꢀ
nitrogen bond cleavage of anilines.4 However, as far as we
know the transition-metal-catalyzed cleavage of carbonꢀ
nitrogen bonds in arylhydrazine has not been reported.5
(1) For reviews, see: (a) Kakiuchi, F.; Murai, S. Acc. Chem. Res. 2002,
35, 826–834. (b) Ritleng, V.; Sirlin, C.; Pfeffer, M. Chem. Rev. 2002, 102,
1731–1770. (c) Beccalli, E. M.; Broggini, G.; Martinelli, M.; Sottocor-
nola, S. Chem. Rev. 2007, 107, 5318–5365. (d) Chen, X.; Engle, K. M.;
Wang, D. H.; Yu, J. Q. Angew. Chem., Int. Ed. 2009, 48, 5094–5115. (e)
Lyons, T. W.; Sanford, M. S. Chem. Rev. 2010, 110, 1147–1169. (f) Bras,
J. L.; Muzart, J. Chem. Rev. 2011, 111, 1170–1214.
(2) For decarboxylative coupling reaction, see: (a) Myers, A. G.;
Tanaka, D.; Mannion, M. R. J. Am. Chem. Soc. 2002, 124, 11250–11251.
(b) Tanaka, D.; Romeril, S. P.; Myers, A. G. J. Am. Chem. Soc. 2005,
127, 10323–10333. (c) Goossen, L. J.; Deng, G. J.; Levy, L. M. Science
2006, 313, 662–664. (d) Goossen, L. J.; Zimmermann, B.; Knauber, T.
Angew. Chem., Int. Ed. 2008, 47, 7103–7106. (e) Goossen, L. J.;
Rodriguez, N.; Melzer, B.; Linder, C.; Deng, G.; Levy, L. M. J. Am. Chem.
Soc. 2007, 129, 4824–4833. (f) Goossen, L. J.; Rodriguez, N.; Linder, C.
J. Am. Chem. Soc. 2008, 130, 15248–15249. (g) Bi, H. P.; Zhao, L.; Liang,
Y. M.; Li, C. J. Angew. Chem., Int. Ed. 2009, 48, 792–795.
(3) For reviews of palladium catalyzed cleavage of activated aromatic
CꢀN bonds, see: (a) Roglans, A.; Pla-Quintana, A.; Moreno-Manas, M.
Chem. Rev. 2006, 106, 4622. (b) Felpin, F. X.; Nassar-Hardy, L.;
Callonnec, F. L.; Fouquet, E. Tetrahedron 2011, 67, 2815–2831. (c)
Taylor, J. G.; Moro, A. V.; Correia, C. R. Eur. J. Org. Chem. 2011, 1403–
1428. For selected pioneering work of transition-metal-mediated
unactivated carbonꢀnitrogen bond cleavage, see: (d) Wenkert, E.; Han,
A.-L.; Jenny, C.-J. J. Chem. Soc., Chem. Commun. 1988, 975–976. (e)
Bonanno, J. B.; Henry, T. P.; Neithamer, D. R.; Wolczanski, P. T.;
Lobkovsky, E. B. J. Am. Chem. Soc. 1996, 118, 5132–5133. (f) Blakey,
S. B.; MacMillan, D. W. C. J. Am. Chem. Soc. 2003, 125, 6046–6047. (g)
Saeki, T.; Son, E.-C.; Tamao, K. Org. Lett. 2004, 6, 617–619. (h) Liu, J.;
Robins, M. J. Org. Lett. 2004, 6, 3421–3423.
(4) (a) Ueno, S.; Chatani, N.; Kakiuchi, F. J. Am. Chem. Soc. 2007,
129, 6098. (b) Koreeda, T.; Kochi, T.; Kakiuchi, F. J. Am. Chem. Soc.
2009, 131, 7238–7239.
(5) Akiyama, F.; Miyazaki, H.; Kaneda, K.; Teranishi, S.; Fujiwara,
Y.; Abe, M.; Taniguchi, H. J. Org. Chem. 1980, 45, 2359–2361.
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10.1021/ol202862t
Published on Web 11/04/2011
2011 American Chemical Society