10024
L. Zhang et al. / Tetrahedron 65 (2009) 10022–10024
another 12 h. And the solvents were extracted. Then toluene
LnCl3
LiNR1R2
(10 mL), YCl3 (0.010 g, 0.05 mmol) were charged. To the mixture
was added benzaldehyde (0.212 g, 2.0 mmol). After stirring the
reaction for 2 days at room temperature, diluted hydrochloric acid
(0.1 M, 1 mL) was then added and the mixture was extracted with
ethyl acetate, dried over anhydrous MgSO4, and filtered. After the
solvents were evaporated, the residue was purified by silica gel
column chromatography by using a mixture of n-hexane and ethyl
acetate (1:1, v/v) as an eluent to give N-phenylbenzamide (1a) as
a white solid in 99% yield (0.195 g). Following similar procedures,
the amides 1b–1w were obtained.
RCH2OH
H2O
R1
R2
Ln N
R
H
RCH2OLi
O
LiNR1R2
RCH2O Ln
C
R
H
O
O
R1
R2
Ln
N
NR1R2
R
Ln
B
Acknowledgements
O
O
Ln
O
The work was supported by the National Natural Science
Foundation of China (20702001, 20832001), and a grant from the
Anhui Education Department (TD200707, KJ2007A011). We are
grateful to Prof. Jiping Hu and Prof. Baohui Du for their assistance in
running NMR and IR spectra.
H
R2R1N
R
H
NR1R2
R
R
H
R
H
O
A
Scheme 1. Proposed mechanism for the reaction catalyzed by LnCl3.
Supplementary data
Supplementary data associated with this article can be found in
3. Conclusion
In summary, a variety of amides were obtained by treatment of
aldehydes with lithium amides in the presence of catalytic amount
of LnCl3. The results indicated that electronic deficient groups on
the anilinide disfavored the reaction, in contrast, the electronic
deficient groups on the aromatic aldehydes favor the reactions. The
features of the economical catalysts, high yields, tolerance of a wide
range of amides and aromatic aldehydes make this methodology an
easy and valid contribution to the direct synthesis of amides from
aldehydes.
References and notes
1. Wu, X.; Hu, L. J. Org. Chem. 2007, 72, 765–774.
2. Selected recent examples: (a) Daniel, G.; David, B.; Simon, W. Tetrahedron Lett.
2008, 49, 5687–5688; (b) Kang, Y.; Chung, H.; Kim, J.; Yoon, Y. Synthesis 2002,
733–738; (c) Azumaya, I.; Okamoto, T.; Imabeppu, F.; Takayanagi, H. Tetrahedron
2003, 59, 2325–2331; (d) Naik, S.; Bhattacharjya, G.; Talukdar, B.; Patel, B. K.
Eur. J. Org. Chem. 2004, 1254–1260; (e) Teichert, A.; Jantos, K.; Harms, K.; Studer, A.
Org. Lett. 2004, 6, 3477–3480; (f) Shendage, D. M.; Froehlich, R.; Haufe, G. Org. Lett.
2004, 6, 3675–3678; (g) Black, D. A.; Arndtsen, B. A. Org. Lett. 2006, 8, 1991–1993;
(h) Katritzky, A. R.; Cai, C.; Singh, S. K. J. Org. Chem. 2006, 71, 3375–3380.
3. Akihiro, G.; Kohei, E.; Susumu, S. Angew. Chem., Int. Ed. 2008, 47, 3607–3609.
4. Experimental
4.1. General
¨
´
´
´
´
´
4. Csaba, C.; Bernadett, B.; Krisztian, N.; Ildiko, K.; Zsolt, S.; Zoltan, B.; Laszlo, U.;
Ferenc, D. Org. Lett. 2008, 10, 1589–1592.
5. (a) Gunanathan, C.; Ben-David, Y.; Milstein, D. Science 2007, 790–792; (b)
Watson, A. J. A.; Maxwell, A. C.; Williams, J. M. J. Org. Lett. 2009, 11, 2667–2670.
6. Tamaru, Y.; Yamada, Y.; Yoshida, Z. Synthesis 1983, 474–476.
7. (a) Annegret, T.; Ivo, R.; Matthias, B. Eur. J. Org. Chem. 2001, 523–528; (b) Shie, J.;
Fang, J. J. Org. Chem. 2003, 68, 1158–1160; (c) Jie, G.; Wang, G. J. Org. Chem. 2008,
73, 2955–2958.
8. Kekeli, E. K.; Christian, W. Org. Lett. 2007, 9, 3426–3432.
9. (a) Vora, H. U.; Rovis, T. J. Am. Chem. Soc. 2007, 129, 13796–13797; (b) Bode, J. W.;
Sohn, S. S. J. Am. Chem. Soc. 2007, 129, 13798–13799.
10. Kazuaki, I.; Takayuki, Y. Org. Lett. 2004, 6, 1983–1986.
11. Zhang, L.; Wang, S.; Zhou, S.; Yang, G.; Sheng, E. J. Org. Chem. 2006, 71,
3149–3153.
12. Wang, S.; Qian, H.; Yao, W.; Zhang, L.; Zhou, S.; Yang, G.; Zhu, X.; Fan, J.; Liu, Y.;
Chen, G.; Song, H. Polyhedron 2008, 27, 2757–2764.
Melting points were determined using a Gallenkamp melting
point apparatus and are uncorrected. 1H NMR spectra were recor-
ded on a Bruker Avance 300 instrument in CDCl3 solutions using
TMS as internal standard. Chemical shifts (d) are reported in parts
per million. IR spectra were obtained with a UV-4100 FT-IR spec-
trometer. Mass spectra were performed on a Micromass GCT-MS
CA064. All aldehydes, amines, and solvents were pre-dried, redis-
tilled or recrystallized before use. The lanthanide chlorides were
prepared according to references.17
13. (a) Sung, Y. S.; Tobin, J. M. Org. Lett. 2008, 10, 317–319; (b) Li, J.; Xu, F.; Zhang, Y.;
Shen, Q. J. Org. Chem. 2009, 74, 2575–2577; (c) Qian, C.; Zhang, X.; Li, J.; Xu, F.;
Zhang, Y.; Shen, Q. Organometallics 2009, 28, 3856–3862.
14. (a) Xu, F.; Luo, Y.; Wu, J.; Shen, Q.; Chen, H. Heteroat. Chem. 2006, 17, 389–392;
(b) Feng, S.; Xu, F.; Shen, Q. Chin. J. Chem. 2008, 26, 1163–1167; (c) Bulgakov, R. G.;
Karamzina, D. S.; Kuleshov, S. P.; Dzhemilev, U. M. Russ. J. Org. Chem. 2008, 44,
470–471; (d) Denise, B. B.; Brachais, C. H.; Adina, C.; Ander, L.; Dider, S. Macromol.
Rapid Commun. 2002, 23, 200–204.
15. Mikami, K.; Terada, M.; Matsuzawa, H. Angew. Chem., Int. Ed. 2002, 41,
3554–3572.
16. Zhu, X.; Fan, J.; Wu, Y.; Wang, S.; Zhang, L.; Yang, G.; Wei, Y.; Yin, C.; Zhu, H.;
Wu, S.; Zhang, H. Organometallics 2009, 28, 3882–3888.
4.2. General procedure for the synthesis of amides from the
reaction of aldehydes with lithium amides catalyzed by
lanthanide chlorides
Under dried argon, to a THF solution PhNH2 (0.093 g, 1.0 mmol)
at ꢁ78 ꢀC in a 30-mL Schlenk tube was slowly added an n-hexane
solution of n-BuLi (0.8 mL, 1 mmol). The temperature of the re-
action mixture was then gradually raised to room temperature after
the addition. The mixture was stirred at room temperature for
17. Taylor, M. D.; Carter, C. P. J. Inorg. Nucl. Chem. 1962, 24, 387–391.