5106
G. B. Dharma Rao, M. P. Kaushik / Tetrahedron Letters 52 (2011) 5104–5106
9. Chavan, S. P.; Shivasankar, K.; Sivappa, R.; Kale, R. Tertrahedron Lett. 2002, 43,
MeO
8583.
O
O
O
O
10. Chavan, S. P.; Subbarao, Y. T.; Dantale, S. W.; Sivappa, R. Synth. Commun. 2001,
31, 289.
Yb3+
Yb3+
+
MeO
O
O
11. Sairre, M. I.; Bronze-Uhle, E. S.; Donate, P. M. Tetrahedron Lett. 2005, 46, 2705.
12. Bandgar, B. P.; Sadavarte, V. S.; Uppalla, L. S. Synlett 2001, 1715.
13. Nottingham, W. D.; Witzeman, J. S. J. Org. Chem. 1991, 56, 1713.
14. Hanamoto, T.; Sugimoto, Y.; Yokoyama, Y.; Inanaga, J. J. Org. Chem. 1996, 61,
4491.
OMe
OH
R'CH2
R'
15. Zhu, X.; Zhu, Du; Fan, Xu; Qi, Shen J. Org. Chem. 2009, 74, 6347.
16. Kumar, A.; Ahmed, I.; Sudershanrao, M. Can. J. Chem. 2008, 86, 899.
17. Dharma Rao, G. B.; Achrya, B. N.; Verma, S. K.; Kaushik, M. P. Tetrahedron Lett.
2011, 52, 809.
R'
O
O
O
O
O
O
MeO
O
O
- MeOH
18. Typical experimental procedure:
A
homogeneous mixture of methyl
Yb3+
Yb3+
acetoacetate (1 mmol) and alcohol (1 mmol) was taken in a round bottomed
flask attached to reflux and a distillation condenser to remove methanol. A
catalytic amount of Yb(OTf)3 (0.3 mmol) was added and the reaction was
heated at 110 °C (oil bath) with constant stirring under solvent-free condition
for a certain period of time as required, and the reaction was monitored by TLC.
After completion of the reaction, the mixture was cooled and the crude b-
ketoester was separated by column chromatography using light petroleum
ether and ethylacetate (80:20) to afford the pure desired product.
OMe
O
O
O
O
R'
R'
2-(dimethylamino) ethyl 3-oxobutanoate (5): IR (mMax): 854, 1175, 1719, 1748,
O
O
2861. 1H NMR (400 MHz, CDCl3) d = 2.289 (s, 9H), 2.569–2.598 (t, J = 5.6 Hz,
2H), 3.495 (s, 2H), 4.233–4.261 (t, J = 5.6 Hz, 2H). 13C NMR (CDCl3) d = 29.706,
45.383, 45.608, 50.059, 58.444, 69.195, 167.212, 200.517. ESI-MS: m/z = 174.21
[M+1].
R'
O
Scheme 2.
Cyclopentyl 3-oxobutanoate (6): IR (mMax): 803, 968, 1151, 1323, 1718, 1740,
2874, 2966. 1H NMR (400 MHz, CDCl3) d = 1.590–1.603 (2H, m), 1.613–1.626
(5H, m), 1.842–1.856 (2H, m), 2.260 (s, 3H), 3.411 (s, 2H). 13C NMR (CDCl3)
d = 23.603, 29.933, 32.592, 50.320, 78.171, 166.809, 200.575. ESI-MS: m/
z = 193.03 [M+23].
Acknowledgments
Phenethyl 3-oxobutanoate (11): IR (mMax): 701, 749, 995, 1031, 1150, 1316,
1717, 1743, 2960. 1H NMR (400 MHz, CDCl3) d = 2.199 (s, 3H), 2.965–2.982 (t,
J = 6.8 Hz, 2H), 3.423 (s, 2H), 4.353–4.370 (t, J = 6.8 Hz, 2H), 7.307 (s, 5H). 13C
NMR (CDCl3) d = 29.858, 34.808, 49.883, 65.576, 126.541, 128.426, 128.736,
137.336, 166.865, 200.618. ESI-MS: m/z = 229.03 [M+23].
The authors are thankful to Mr. A. N. Rao for providing alcohols
and Mr. Ajay Pratap for NMR spectral data. The authors express
special thanks to Dr. R. Vijayaraghavan, Director, DRDE, Gwalior
for his keen interest and encouragement.
3,7-dimethylocta-2,6-dienyl 3-oxobutanoate (12): IR (mMax): 802, 958, 1150,
1233, 1314, 1378, 1446, 1648, 1719, 2929, 2968. 1H NMR (400 MHz, CDCl3)
d = 1.602 (s, 3H), 1.682 (s, 3H), 1.769 (s, 3H), 2.119–2.144 (m, 4H), 2.263 (s, 3H),
References and notes
3.438 (s, 2H), 4.612–4.643 (d, 2H), 5.088–5.072 (t, 1H), 5.335–5.370 (t, 1H). 13
C
NMR (CDCl3) d = 17.601, 23.433, 25.622, 26.578, 30.022, 32.143, 50.102,
61.950, 118.557, 132.209, 143.228, 167.068, 200.433. ESI-MS: m/z = 261.09
[M+23].
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3. Grasa, G. A.; Singh, R.; Nolan, S. P. Synthesis 2004, 7, 971.
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Ravindranathan, T. Tetrahedron Lett. 1996, 37, 233.
3-methylbut-3-enyl 3-oxobutanoate (14): IR (mMax): 803, 895, 1040, 1151, 1317,
1451, 1719, 1744, 2970, 3079. 1H NMR (400 MHz, CDCl3) d = 1.755 (s, 3H),
2.264 (s, 3H), 2.346–2.381 (t, J = 6.8 Hz, 2H), 3.445 (s, 2H), 4.248–4.282 (t,
J = 6.8 Hz, 2H), 4.739–4.814 (d/d, 1H). 13C NMR (CDCl3) d = 22.191, 29.889,
36.398, 49.891, 63.288, 112.303, 141.164, 166.898, 200.232. ESI-MS: m/
z = 193.06 [M+23].
8. (a) Jin, T. S.; Zhang, S. L.; Li, T. S. Green Chem. 2002, 4, 32; (b) Bandgar, B. P.;
Pandit, S. S.; Sadavarte, V. S. Green Chem. 2001, 3, 247.