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RSC Advances
Page 3 of 4
DOI: 10.1039/C5RA05131B
Journal Name
COMMUNICATION
In summary, we have developed a novel palladium-catalyzed Heck
coupling of arylhydrazines via aryl C–NHNH2 bond activation with
olefins. By employing the commercially available arylhydrazine as
the coupling partner and the cheap and manageable TsCl as the
activation reagent, this effective methodology will be attractive for
both academia and industry. This new methodology can be used as
a complement for the classical Heck coupling reaction.
Acknowledgements
Scheme 2 Heck coupling of arylhydrazine with styrene.
This work was supported by the Science and Technology Project of
Jiangxi Provincial Education Department (No. GJJ14450), and the
Open Project Program of Key Laboratory of Functional Small
Organic Molecule, Ministry of Education, Jiangxi Normal University
(No. KLFS-KF-201406).
To explore the mechanism of this Heck reaction, two control
experiments were carried out (Scheme 3). We conceived that
phenylhydrazine derivatives 1a’ and 1a’’ would be generated as the
key intermediates for this C–NHNH2 bond activation process. As
described in Scheme 3, 1-phenyl-2-tosyldiazene 1a’’ could be
isolated in 24% yield from N’-tosyl phenylhydrazine 1a’ under basic
conditions, and the direct Heck coupling between 1a’’ and 2a
smoothly afforded 3a in 84% yield.
Notes and references
1
(a) The Mizoroki-Heck Reaction, ed. M. Oestreich, Wiley,
Chichester (UK), 2009; (b) I. P. Beletskaya and A. V.
Cheprakov, Chem. Rev., 2000, 100, 3009; (c) Metal-Catalyzed
Cross-Coupling Reactions, ed. F. Diederich and A. Meijere,
Wiley-VCH, Weinheim, Germany, 2004.
2
(a) L. E. Overman, D. J. Ricca and V. D. Tran, J. Am. Chem. Soc.,
1993, 115, 2042; (b) Comprehensive Organic Transformations:
A Guide to Functional Group Preparations, 2nd ed. R. C.
Larock, VCH, New York, 1999; (c) The Chemistry of Alkenes, ed.
S. Patai, Wiley, New York, 1964.
Scheme 3 Control experiments.
3
4
(a) R. R. Bader, P. Baumeister and H. U. Blaser, Chimia, 1996,
50, 99; (b) Catalysis of Organic Reactions, ed. F. E. Herkes,
Marcel Dekker, New York, 1998.
Based on these results and the research findings from other
groups, a possible mechanism for this Heck reaction via C–NHNH2
bond activation was proposed (Fig. 1). Firstly, arylhydrazine could
quickly react with TsCl to form N’-tosyl arylhydrazine I, which was
dehydrogenated in the presence of base and Pd(II)-catalyst to
provide the diazene II, accompany with the in situ generation of
Pd(0) active species. In addition, diazene II was in equilibrium with
the corresponding diazonium ion III, when it was dissolved in
solvent.11 Then oxidative addition of III to the Pd(0) gave the
organopalladium intermediate IV, which could be transformed to
(a) Handbook of Polymer Synthesis, 2nd ed. H. R. Kricheldorf,
O. Nuyken and G. Swift, Marcel Dekker, NewYork, 2005; (b)
Handbook of Metathesis, Vols. 1-3, ed. R. H. Grubbs, Wiley-
VCH, Weinheim, 2003.
5
6
7
8
(a) A. Roglans, A. Pla-Quintana and M. Moreno-Mañas, Chem.
Rev., 2006, 106, 4622; (b) F. Mo, G. Dong, Y. Zhang and J.
Wang, Org. Biomol. Chem., 2013, 11, 1582.
(a) S. B. Blakey and D. W. C. MacMillan, J. Am. Chem. Soc.,
2003, 125, 6046; (b) D. V. Partyka, Chem. Rev., 2011, 111,
1529.
intermediate
V in the presence of olefin. Degeneration of
intermediate V gave a coupling product and regenerated [Pd(0)].
The catalytic cycle was closed upon reoxidation of Pd(0) to Pd(II) by
air.
(a) T. Saeki, E.-C. Son and K. Tamao, Org. Lett., 2004, 6, 617; (b)
X.-F. Wu, H. Neumann and M. Beller, Chem. Soc. Rev., 2011,
40, 4986.
(a) M.-K. Zhu, J.-F. Zhao and T.-P. Loh, Org. Lett., 2011, 13,
6308; (b) Y. Chen, S. Guo, K. Li, J. Qu, H. Yuan, Q. Hua and B.
Chen, Adv. Synth. Catal., 2013, 711; (c) Z. Peng, G. Hu, H. Qiao,
P. Xu, Y. Gao and Y. Zhao, J. Org. Chem., 2014, 79, 2733.
(a) J.-B. Liu, H. Yan, H.-X. Chen, Y. Luo, J. Weng and G. Lu,
Chem. Commun., 2013, 49, 5268; (b) J.-B. Liu, L. Nie, H. Yan, L.-
H. Jiang, J. Weng and G. Lu, Org. Biomol. Chem., 2013, 11,
8014; (c) J.-B. Liu, H.-P. Zhou and Y.-Y. Peng, Tetrahedron Lett.,
2014, 55, 2872; (d) H.-P. Zhou, J.-B. Liu, J.-J. Yuan and Y.-Y.
Peng, RSC Adv., 2014, 4, 25576.
9
Fig. 1 Proposed mechanism.
10 (a) S. R. Dubbaka and P. Vogel, Chem. Eur. J., 2005, 11, 2633;
(b) G.-W. Wang and T. Miao, Chem. Eur. J., 2011, 17, 5787.
Conclusions
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