SPECIAL TOPIC
1-Aza-2-siloxybutadiene: Structure and Synthetic Application
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1H NMR (400 MHz, CDCl3): d = 8.82 (br s, 1 H), 7.60–7.07 (m, 10
H), 6.41 (dd, J = 16.6, 1.7 Hz, 1 H), 6.00 (dd, J = 16.6, 10.2 Hz, 1
H), 5.57 (dd, J = 10.2, 1.7 Hz, 1 H), 4.19 (t, J = 6.7 Hz, 2 H), 2.73
(t, J = 6.7 Hz, 2 H).
13C NMR (100 MHz, CDCl3): d = 168.4, 166.5, 140.9, 138.1, 129.8,
128.8, 128.6, 128.3, 128.2, 128.0, 124.0, 119.8, 46.0, 36.6.
Acknowledgment
This work was financially supported by the Fujisawa Foundation
and a Grant-in-Aid from the Ministry of Education, Culture, Sports,
Science and Technology, Japan.
HRMS: m/z [M+] calcd for C18H18N2O2: 294.1368; found:
References
294.1367.
(1) (a) Carruthers, W. Cycloaddition Reactions in Organic
Synthesis; Pergamon Press: Oxford, 1990.
Compound 3a* (98% 15N-enriched)
(b) Cycloaddition Reactions in Organic Synthesis;
Kobayashi, S.; Jørgensen, K. A., Eds.; Wiley-VCH:
Weinheim, 2002.
IR (neat): 2939, 1652, 1598 cm–1.
1H NMR (600 MHz, CDCl3): d = 7.26 (t, J = 7.7 Hz, 2 H), 7.03 (t,
J = 7.7 Hz, 1 H), 6.76 (d, J = 7.7 Hz, 2 H), 6.09 (d, J = 4.0 Hz, 1 H),
6.08 (d, J = 8.4 Hz, 1 H), 5.53 (dd, J = 8.4, 4.0 Hz, 1 H), 1.01 (s, 9
H), 0.35 (s, 6 H).
13C NMR (150 MHz, CDCl3): d = 156.3 (d, JC-N = 12.9 Hz), 148.0
(d, JC-N = 2.9 Hz), 128.8, 125.4, 125.2, 122.9, 121.3, 25.9, 18.1,
–4.6.
(2) (a) Boger, D. L.; Weinreb, S. M. Hetero Diels–Alder
Methodology in Organic Synthesis; Academic Press: San
Diego, 1987. (b) Jayakumar, S.; Ishar, M. P. S.; Mahajan, M.
P. Tetrahedron 2002, 58, 379.
(3) Synthesis of piperidines by intermolecular
cyclodimerization of acrylamide equivalents: (a) Lorente,
A.; Navio, J. L. G.; Perez, J. C. L.; Soto, J. L. Synthesis 1985,
89. (b) Elliott, M. C.; Galea, N. M.; Long, M. S.; Willock, D.
J. Tetrahedron Lett. 2001, 42, 4937.
15N NMR (60 MHz, CDCl3): d = 258.1.
29Si NMR (120 MHz): d = 23.5.
(4) Synthesis of piperidines by intramolecular cycloaddition of
a,b-unsaturated amides: (a) Ihara, M.; Ishida, Y.; Tokunaga,
Y.; Kabuto, C.; Fukumoto, K. J. Chem. Soc., Chem.
Commun. 1995, 2085. (b) Toyota, M.; Komori, C.; Ihara, M.
J. Org. Chem. 2000, 65, 7110. (c) Mekouar, K.; Genisson,
Y.; Leue, S.; Greene, A. E. J. Org. Chem. 2000, 65, 5212.
(5) Takasu, K.; Nishida, N.; Ihara, M. Tetrahedron Lett. 2003,
44, 7429.
UV–Vis (CH3CN): lmax = 297 nm.
Compound 3b* (98% 15N-enriched)
IR (KBr): 1661, 1626, 1595 cm–1.
1H NMR (600 MHz, CDCl3): d = 7.42 (d, J = 15.3 Hz, 1 H), 7.36–
7.30 (m, 7 H), 7.08 (t, J = 7.8 Hz, 1 H), 6.84 (t, J = 7.7 Hz, 2 H),
6.43 (d, J = 15.3 Hz, 1 H), 1.07 (s, 9 H), 0.41 (s, 6 H).
(6) Jones, K.; Wilkinson, J.; Ewin, R. Tetrahedron Lett. 1994,
35, 7673.
(7) For comparable examples, structural analysis of silylated
benzamides: (a) Klebe, J. F. Acc. Chem. Res. 1970, 3, 299.
(b) Misaki, T.; Kurihara, M.; Tanabe, Y. Chem. Commun.
2001, 2478.
(8) Levy, G. C.; Lichter, R. L. Nitrogen-15 Nuclear Magnetic
Resonance Spectroscopy; John Wiley & Sons: New York,
1979.
13C NMR (150 MHz, CDCl3): d = 156.7 (d, JC-N = 13.0 Hz), 148.2,
139.4, 135.5, 129.0, 128.8, 128.6, 127.7, 122.9, 121.6, 115.7, 26.0,
–4.5.
15N NMR (60 MHz, CDCl3): d = 259.0.
29Si NMR (120 MHz, CDCl3): d = 23.6.
UV–Vis (CH3CN): lmax = 326 nm.
(9) Jancke, H.; Engelhardt, G.; Wagner, S.; Dirnens, W.;
Herzog, G.; Tieme, E.; Rühlmann, K. J. Organomet. Chem.
1977, 134, 21.
Synthesis 2004, No. 13, 2222–2225 © Thieme Stuttgart · New York