RSC Advances
Communication
J. S. Y. Ngiam, A. M. Seayad, D. T. Tuan, C. W. Johannes and
A. Chen, Tetrahedron Lett., 2013, 54, 4922–5492.
4 For selected articles for the transition metal-catalyzed
9 For carbene-catalyzed oxidation of aldehydes to carboxylic
acids, see: P.-C. Chiang and J. W. Bode, Org. Lett., 2011, 13,
2422–2425.
oxidative amidation of aldehydes, see: (a) A. Tillack, 10 For carbene-catalyzed oxidative esterication of aldehydes,
I. Rudloff and M. Beller, Eur. J. Org. Chem., 2001, 523–528;
(b) W.-J. Yoo and C.-J. Li, J. Am. Chem. Soc., 2006, 128,
13064–13065; (c) J. W. W. Chang and P. W. H. Chan,
Angew. Chem., Int. Ed., 2008, 47, 1138–1140; (d) S. Seo and
T. J. Marks, Org. Lett., 2008, 10, 317–319; (e) L. Wang,
H. Fu, Y. Jiang and Y. Zhao, Chem.–Eur. J., 2008, 14, 10722–
10726; (f) C. Qian, X. Zhang, J. Li, F. Xu, Y. Zhang and
Q. Shen, Organometallics, 2009, 28, 3856–3862; (g) J. Li,
F. Xu, Y. Zhang and Q. Shen, J. Org. Chem., 2009, 74, 2575–
2577; (h) S. C. Ghosh, J. S. Y. Ngiam, C. L. L. Chai,
A. M. Seayad, T. T. Dang and A. Chen, Adv. Synth. Catal.,
2012, 354, 1407–1412; (i) S. C. Ghosh, J. S. Y. Ngiam,
A. M. Seayad, D. T. Tuan, C. L. L. Chai and A. Chen, J. Org.
Chem., 2012, 77, 8007–8015; (j) C. Zhang, X. Zong, L. Zhang
and N. Jiao, Org. Lett., 2012, 14, 3280–3283; (k) H. Yao and
K. Yamamoto, Chem.–Asian J., 2012, 7, 1542–1545.
see: (a) J. Guin, S. De sarkar, S. Grimme and A. Studer,
Angew. Chem., Int. Ed., 2008, 47, 8727–8730; (b) B. E. Maki
and K. A. Scheidt, Org. Lett., 2008, 10, 4331–4334; (c)
C. Noonan, L. Baragwanath and S. J. Cannon, Tetrahedron
Lett., 2008, 49, 4003–4006; (d) B. E. Maki, A. Chan,
E. M. Phillips and K. A. Scheidt, Tetrahedron, 2009, 65,
3102–3109; (e) S. De Sarkar, S. Grimme and A. Studer,
J. Am. Chem. Soc., 2010, 132, 1190–1191; (f) C. A. Rose and
K. Zeitler, Org. Lett., 2010, 12, 4552–4555; (g) B. Maji,
S. Vedachalan, X. Ge, S. Cai and X.-W. Liu, J. Org. Chem.,
2011, 76, 3016–3023; (h) E. E. Finney, K. A. Ogawa and
A. J. Boydston, J. Am. Chem. Soc., 2012, 134, 12374–12377;
(i) P. Arde, B. T. Ramanjaneyulu, V. Reddy, A. Saxena and
R. V. Anand, Org. Biomol. Chem., 2012, 10, 848–851; (j)
T. Uno, T. Inokuma and Y. Takemoto, Chem. Commun.,
2012, 48, 1901–1903; (k) I. N. C. Kiran, K. Lalwani and
¨
5 For the oxidative amidation of aldehydes in the absence of
carbene catalysts, see: (a) K. Ekoue-Kovi and C. Wolf, Org.
Lett., 2007, 9, 3429–3432; (b) J.-J. Shie and J.-M. Fang,
J. Org. Chem., 2003, 68, 1158–1160; (c) K. Xu, Y. Hu,
A. Sudalai, RSC Adv., 2013, 3, 1695–1698; (l) L. Mohlmann,
S. Ludwig and S. Blechert, Beilstein J. Org. Chem., 2013, 9,
602–607; (m) J. Zhao, C. Muck-Lichtenfeld and A. Studer,
¨
Adv. Synth. Catal., 2013, 355, 1098–1106.
S. Zhang, Z. Zhan and Z. Wang, Chem. Eur. J., 2012, 18, 11 For carbene-catalyzed amidation of unactivated esters, see:
9793–9797.
M. Movassaghi and M. A. Schmidt, Org. Lett., 2005, 7,
2453–2456.
6 For carbene-catalyzed oxidative amidation of aldehydes, see:
(a) S. D. Sarkar and A. Studer, Org. Lett., 2010, 12, 1992–1995; 12 M. Ji, X. Wang, Y. N. Lim, Y.-W. Kang and H.-Y. Jang, Eur.
(b) S. Kuwano, S. Harada, R. Oriez and K.-i. Yamada, Chem.
Commun., 2012, 48, 145–147.
J. Org. Chem., 2013, 7881–7885.
13 For references presenting pKa values of alcohols, see: (a)
W. A. Sheppard, J. Am. Chem. Soc., 1970, 92, 5419–5422; (b)
L. Eberson, M. P. Hartshorn, O. Persson and F. Radner,
Chem. Commun., 1996, 2105–2112; (c) Y.-M. Shen,
W.-L. Duan and M. Shi, Adv. Synth. Catal., 2003, 345,
337–340.
7 For carbene-catalyzed redox amidation of aldehydes, see: (a)
H. U. Vora and T. Rovis, J. Am. Chem. Soc., 2007, 129, 13796–
13797; (b) J. W. Bode and S. S. Sohn, J. Am. Chem. Soc., 2007,
129, 13798–13799; (c) H. U. Vora, P. Wheeler and T. Rovis,
Adv. Synth. Catal., 2012, 354, 1617–1639.
8 For reviews of NHC-catalyzed reactions, see: (a) D. Enders 14 In our previous publication (ref. 12), the IPr carbene showed
and T. Balensiefer, Acc. Chem. Res., 2004, 37, 534–541; (b)
K. Zeitler, Angew. Chem., Int. Ed., 2005, 44, 7506–7510; (c)
D. Enders, O. Niemeier and A. Henseler, Chem. Rev., 2007,
better activitity than the IMes carbene in the oxidative
esterication of aldehydes. However, in the one-pot
reaction involving oxidation of allylic alcohols and
oxidative esterication, IMes showed better conversion
than IPr. The catalytic activity of carbenes seems different
depending on reaction conditions.
´
´
107, 5606–5655; (d) N. Marion, S. Dıez-Gonzalez and
S. P. Nolan, Angew. Chem., Int. Ed., 2007, 46, 2988–3000; (e)
H. U. Vora and T. Rovis, Aldrichimica Acta, 2011, 44, 3; (f)
J. Mahatthananchai and J. W. Bode, Chem. Sci., 2012, 3, 15 In the absence of TEMPO, redox esterication occurred to
192–197; (g) S. De Sarkar, A. Biswas, R. C. Samanta and
A. Studer, Chem.–Eur. J., 2013, 19, 4664–4678, Carbene-
catalyzed oxidation.
afford saturated amide 1d.
28228 | RSC Adv., 2014, 4, 28225–28228
This journal is © The Royal Society of Chemistry 2014