J. Chil. Chem. Soc., 58, Nº 4 (2013)
nitrogen ligands properties and that selectivity was greater than with the
Pd(II)/triphenylphosphine system. These systems were studied using in situ
palladium(II) (1 equiv.) and P-N ligands L2 = Ph2P-2-(NH)PyN-PPh2 (2
equiv.), reporting high conversion and moderate selectivity of the double
carbonylation of aryl iodide; on the other hand, in situ Pd(II) (1 equiv.) systems
with ligand L3 = 2-(NH)Py-PPh2 (2 equiv.) reported an activity of 97 % with
high selectivity towards the αketoamide product. When we compare the
basicity of ligands L and L3 (entries 2, 3), problably the lower basicity of the L
ligand favors the sel2ectivity of the reaction to the double carbonylation of ary3l
iodide; however, in both experiments (entries 2 and 3) the conversions were
near 100%. When the catalytic reaction was carried out using a pre-catalyst
previously synthesized from Pd(II) acetate with a PN-type ligand such as L3,
the activity achieved by the resulting Pd(2-(NH)Py-PPh )2(OAc) complex was
only 74%, but the selectivity was 94% for the double2carbony2lation of aryl
iodide Normally the pre-formed catalyst complex increases the control on the
selectivity of the reaction, so perhaps when the reaction was made using an in
situ Pd(II)/ L3= 2-(NH)Py-PPh2 system, the reaction promotes the formation of
other palladium complexes that are not selective for the double carbonylation.
A similar behavior was seen when the Pd(2-(CH2)Py-PPh2) (OAc)2 and
Pd(8-(PPh2)Qn-PPh2)2(OAc)2 complexes were studied. The P2d(2-(CH2)Py-
PPh2)2(OAc)2 complex (entry 6) reported 99% conversion with 89% selectivity
for the α-ketoamides after only 4 hours of reaction, while the Pd(8-(PPh )Qn-
PPh2) (OAc) complex (entry 7) reported lower conversion (58%) but2 high
select2ivity (926%) for the N,N-diethyl-α-oxo benzeneacetamide. When Pd(OAc)2
was studied as test reaction, the palladium compound decompose rapidly to
palladium metal. In the presence of phosphorus-nitrogen ligands the generation
of palladium metal is avoided. We found a series of palladium complexes
containing phosphorus-nitrogen ligands with high activity and selectivity for
the catalytic synthesis of N,N-diethyl-α-oxo benzeneacetamide. The product of
the catalytic reaction is easy to purify by column chromatography using basic
alumina in dichloromethane. Comparing the results reported here with those
reported in the literature it is possible to point that our systems require only
4 hours of reaction to achieve high activities and selectivities. Other studies
using palladium catalysts [16,17] and copper catalysts [18-20] have shown
longer reaction time for the aminocarbonylation (over 10 hours), with lower
selectivity compared to those reported here. On the other hand, the amount of
catalyst required for the aminocarbonylation of the aryl iodide reaction in our
study is less than that reported in the literature [7], giving higher yields.
CONCLUSIONS
We developed a series of transition-metal-catalyzed systems using
homogenous palladium complexes containing phosphorus-nitrogen ligands
that are very active in the aminocarbonylation of aryl iodide reaction. The
synthesized complexes showed conversions between 58%-100%. Several
complexes studied in this work reported high selectivity for the ketocarboxyl
amine after only 4 hours of reaction.
ACKNOWLEDGEMENTS
We wish to express our thanks for the financial support provided by
Fondecyt-Chile (Grant 1120149).
REFERENCES
1. E. Szanti-Pinter, J. Balogh, Z. Csok, L. Kollár, A. Gomory, R. Skoda-
Foldes. Steroids, 2001, 76, 1377.
2. Z. Trzeciak. Coord. Chem. Rev. 2005, 249, 2308.
3. P. Aguirre, C. Lagos, S.A Moya, C. Zúñiga, C. Vera-Oyarce, E. Sola, G.
Peris, J.C Bayón. Dalton Trans. 2007, 46, 5419.
4. X-F. Wu, J. Schranck, H. Neumann, M. Beller. Tetrahedron Letters.
2011, 52, 3702.
5. P.J. Tambade, Y.P. Patil, B.M. Bhanage. Appl. Organometal. Chem.
2009, 23, 235.
6. (a) B. Malawskai, K. Kulig, J. Gajda, D. Szczeblewki, A. Musaial, K.
Wickowski, D. Maciag, J.P. Stables. Acta Pol. Pharm. Drug Res. 2007,
64, 127; (b) B. Malawska. Curr. Top. Med. Chem. 2005, 5, 69; (c) J.J.
Luszczki, M.J. Swiader, K. Swiader, R. Paruszewski, W.A. Turski, S.
Czuczwar. J. Fund. Clin. Pharmacol. 2008, 22, 69.
7. R. Skoda-Foldes, L. Kollar. Curr. Org. Chem. 2002, 6, 1097.
8. A. Arcadi. Carbonylation of Enolizable Ketones (Enol Triflates) and
Iodoalkenes (Chapter 9) In Modern Carbonylation Methods; Kollar, L.,
Ed.; Wiley-VCH: Weinheim, 2008, 223.
9. Applied Homogeneous Catalysis with Organometallic Compounds; B.
Cornils, W. A. Herrmann. Eds.; Wiley-VCH: Weinheim, 1996.
10. Transition Metals for Organic Synthesis; M. Beller, C. Bolm. Eds.;
Wiley-VCH:Weinheim, 1998.
11. S. Álvarez, R. Álvarez, H. Khanwalkar, P. Germain, G. Lemaire, F.
Rodríguez-Barrios, H. Gronemeyer and Á. R. de Lera. Bioorg. Med.
Chem. 2009, 17, 4345.
Table1:Catalyticactivitiesofpalladiumcompoundsinaminocarbonylation
of Aryl iodide.
12. J. L. Jesuraj and J. Sivaguru. Chem. Commun. 2010, 4791.
13. F. Heaney, J. Fenlon, P. McArdle and D. Cunningham. Org. Biomol.
Chem. 2003, 1, 1122.
Selectivity
%
Pd(II)/Ligand or
palladium complex
Conversion
Entry
%
14. T. D. Ocain and D. H. Rich. J. Med. Chem.1992, 35, 451.
15. F. Ozawa, H. Soyama, H. Yanagihara, I. Aoyama, H. Takino, K. Izawa,
T. Yamamoto and A. Yamamoto. J. Am. Chem. Soc., 1985, 107, 3235.
16. Z. Tao, C. Zhen-Chu. J. Chem. Research (S), 2001, 116.
17. J. Liu, S. Zheng, W. SUN, C. Xia Chin. J.of Chem., 2009, 27, 623.
18. J. Liu, R. Zhang, S. Wang, W. Sun, and C. Xia. Org. Lett., 2009, 11, 6.
19. M. Wen-Peng, W. Hui-Hui, L. Zhi-Cheng, Y. Jin-Wei, X. Yong-Mei,Y.
Liang-Ru M. Pu and Q. Ling-Bo. Chem. Commun., 2012, 48, 10117.
20. J. Zhang, Y.Wei, S. Lin, F. Liang and P.Liu. Org. Biomol. Chem., 2012,
10, 9237.
ratio 2/1a
1
2
3
4
5
6
7
Pd/PPh3
Pd/L2
96
100
97
71/29
60/40
90/10
94/6
Pd/L3
Pd(2-(NH)Py-PPh2)2(OAc)2
Pd(2-(CH3NH)Py-PPh2)2(OAc)2
Pd(2-(CH2)Py-PPh2)2(OAc)2
Pd(8-(PPh2)Qn-PPh2)2(OAc)2
74
99
71/29
89/11
96/4
99
58
Conditions: substrate/catalyst ratio 100:1, 1.5 mL Et3N, 10 mL DMF, 30
bar CO
T= 90 °C. Reaction time = 4 hours. a ratio of the products (2)/(1). Pd(OAc)2
used as test reaction yield 10% conversion with inverse selectivity (1)/(2)=
92/8.
2137