LETTER
Niobium Pentachloride-mediated Nucleophilic Additions to Cyclic N-Acyliminium Ions
1191
References
[C(O)-CH ], 58.9 [C(O)-CH-C(O)], 60.7 (-NCH), 62.3
3
(
O-CH ), 167.6 [-C(O)-O-CH ], 175.3 [C(O)-NCH ], 201.0
2
2
3
(
1) Speckamp, W. N.; Moolenaar, N. J. Tetrahedron 2000, 56,
827.
2) (a) Howarth, J.; Gillespie, K. Tetrahedron Lett. 1996, 37,
011. (b) Howarth, J.; Gillespie, K. Molecules 2000, 5, 993.
c) Constantino, M. G.; Júnior, V. L.; da Silva, G. V. J.
[
-C(O)-CH3].
3
1
Compound 12: H NMR (300 MHz, CDCl ): d = 2.13–2.69
[
3
(
m, 4 H, C(O)-CH -CH - and C(O)-CH -CH -], 2.93 (s, 3 H,
2 2 2 2
6
(
N-CH ), 4.90 (t, 1 H, -CH-NCH , J = 6.9 Hz), 7.13 (ddd, 1
3
3
H, aromatic, J = 1.1, 7.0, 8.0 Hz), 7.22 (ddd, 1 H, aromatic,
Molecules 2002, 7, 456.
J = 1.2, 7.3, 8.4 Hz), 7.44 (d, 1 H, aromatic, J = 8.0 Hz), 7.54
(
(
(
3) Constantino, M. G.; Júnior, V. L.; Aragão, V. Molecules
13
(
(
d, 1 H, aromatic, J = 7.8 Hz), 9.10 (br s, 1 H, NH). C NMR
75 MHz, CDCl ): d = 27.1 [-C(O)-CH -CH -CH], 28.1 (N-
2
001, 6, 770.
4) Kobayashi, S.; Busujima, T.; Nagayama, S. Chem.–Eur. J.
000, 6, 3491.
3
2
2
CH ), 29.8 [-C(O)-CH -CH ], 58.1 (-CH-NCH ), 111.9
3
2
2
3
2
(
CH, aromatic), 115.2 (C , aromatic), 118.8 (CH, aromatic),
0
5) (a) Andrade, C. K. Z.; Azevedo, N. R.; Oliveira, G. R.
Synthesis 2002, 928. (b) Andrade, C. K. Z.; Azevedo, N. R.
Tetrahedron Lett. 2001, 42, 6473.
120.0 (CH, aromatic), 122.5 (CH, aromatic), 122.8 (CH,
aromatic), 125.4 (C , aromatic), 137.2 (HN-C-CH), 175.4
0
(
N-C=O).
(
(
(
6) Andrade, C. K. Z.; Oliveira, G. R. Tetrahedron Lett. 2002,
1
Compound 13: H NMR (300 MHz, CDCl ): d = 1.60–1.87
(
3
43, 1935.
m, 4 H, CH -CH -CH -CH), 2.14–2.50 [m, 4 H, -C(O)-
2 2 2
7) Hubert, J. C.; Wijnberg, J. B. P. A.; Speckamp, W. N.
Tetrahedron 1975, 31, 1437.
8) Typical Experimental Procedure: To a NbCl (0.6 mmol)
CH -CH and -CH -CH=CH ], 2.91 (s, 3 H, N-CH ), 3.30–
2
2
2
2
3
3
.36 (m, 1 H, CH-NCH ), 5.04–5.13 (m, 2 H, -CH=CH ),
3
2
13
5
5.56–5.77 (m, 1 H, -CH=CH2). C NMR (75 MHz, CDCl3):
d = 5.7 (CH -CH -CH ), 14.5 (CH -CH -CH), 20.1 [-C(O)-
CH -CH ], 21.5 (N-CH ), 25.3 (CH -CH=CH ), 46.6 (N-
suspension in CH Cl (3 mL) at 0 °C, under an argon
atmosphere, was added substrate 1 or 2 (1.0 mmol), diluted
2
2
2
2
2
2
2
2
2
3
2
2
in CH Cl (2 mL). After 20 min, the nucleophile (2.0 mmol)
2
2
CH-CH -), 106.4 (CH=CH ), 122.0 (-CH=CH ), 158.7
2 2 2
was added. After 2 h, the reaction was quenched with sat.
NaHCO (4 mL), extracted with CH Cl (2 × 10 mL), dried
with Na SO and concentrated at reduced pressure to furnish
the crude products 9–15, which were purified by silica gel
(
C=O).
1
3
2
2
Compound 14: H NMR (300 MHz, CDCl ): d = 1.60–1.97
(m, 4 H, CH -CH -CH -CH), 2.17 [s, 3 H, C(O)-CH ], 2.34–
3
2
4
2
2
2
3
2
.40 [m, 2 H, C(O)-CH -CH ], 2.68–2.76 [m, 2 H, CH-CH -
2
2
2
chromatography (10% MeOH in EtOAc).
C(O)], 2.87 (s, 3 H, N-CH ), 3.80–3.94 (m, 1 H, CH-NCH ).
3
3
(
9) Selected spectroscopic data for compounds 9–15:
13
C NMR (75 MHz, CDCl ): d = 5.6 (CH -CH -CH ), 15.7
3
2
2
2
1
Compound 9: H NMR (300 MHz, CDCl ): d = 1.75–1.80
3
(CH -CH -CH), 17.8 [CH -C(O)-CH ], 18.9 [CH -C(O)-
2 2 3 2 2
(
m, 2 H, -CH -CH -CH), 2.10–2.20 (m, 2 H, -CH-CH -
2
2
2
NCH ], 20.0 [C(O)-CH ], 34.6 (N-CH ), 42.5 (N-CH-CH ),
3 3 3 2
CH=CH ), 2.75–2.79 [m, 2 H, -C(O)-CH -CH ], 2.78 (s, 3
H, N-CH ), 3.51–3.59 (m, 1 H, -CH-NCH ), 5.08–5.16 (m,
2
2
2
158.5 (C=O), 193.9 [C(O)-CH ].
3
1
3
3
Compound 15: H NMR (300 MHz, CDCl ): d = 1.63–1.94
(m, 2 H, CH -CH-NCH ), 2.09–2.60 [m, 4 H, C(O)-CH -
3
1
3
2
H, -CH=CH ), 5.60–5.80 (m, 1 H, -CH=CH ). C NMR
2
2
2
3
2
(
75 MHz, CDCl ): d = 23.4 [-C(O)-CH -CH -CH], 28.0 (N-
3
3
2
2
CH ], 2.94 (s, 3 H, N-CH ), 4.90 (t, 1 H, CH -CH-NCH ,
2 3 2 3
CH ), 30.1 [-C(O)-CH -CH ], 37.6 (CH-CH -CH=CH ),
2
2
2
2
J = 5.1 Hz), 7.01 (d, 1 H, CH-NH, J = 2.5 Hz), 7.10–7.27
59.5 (N-CH-CH -), 119.1 (-CH=CH ), 132.8 (-CH=CH ),
2 2 2
(m, 1 H, aromatic), 7.42 (d, 1 H, aromatic, J = 8.0 Hz), 7.55
175.5 (C=O).
13
(
d, 1 H, aromatic, J = 7.6 Hz), 8.83 (br s, N-H). C NMR (75
1
Compound 10: H NMR (300 MHz, CDCl ): d = 1.35–1.70
3
MHz, CDCl ): d = 17.9 (CH -CH -CH ), 30.4 (CH-CH -
3 2 2 2 2
(
m, 2 H, CH-CH -CH ), 1.90–2.10 [m, 2 H, CH-CH -C(O)],
2
2
2
CH ), 32.1 [C(O)-CH ], 34.3 (N-CH ), 56.9 (-CH-NCH ),
2 2 3 3
2.05 [s, 3 H, C(O)CH ], 2.30–2.70 [m, 2 H, -C(O)-CH -
3
2
111.8 (CH, aromatic), 116.2 (C , aromatic), 118.6 (CH,
0
CH ], 2.60 (s, 3 H, N-CH ), 3.50–3.80 (m, 1 H, -CH-NCH ).
2
3
3
aromatic), 119.9 (CH, aromatic), 122.4 (CH, aromatic),
1
Compound 11: H NMR (300 MHz, CDCl ): d = 1.28 (t,
major isomer, -O-CH -CH , J = 7.0 Hz), 1.32 (t, minor
isomer, -O-CH -CH , J = 8.0 Hz), 1.90–2.10 (m, 2 H, CH -
3
122.5 (CH, aromatic), 125.6 (C , aromatic), 137.0 (HN-C-
0
2
3
CH), 171.3 (N-C=O).
2
3
2
(10) (a) Lee, Y. S.; Kang, S. S.; Choi, J. H.; Park, H. Tetrahedron
1997, 53, 3045. (b) D’Oca, M. G. M.; Moraes, L. A. B.;
Pilli, R. A.; Eberlin, M. N. J. Org. Chem. 2001, 66, 3854.
(11) For an example, see: Ollero, L.; Mentink, G.; Rutjes, F. P. J.
T.; Speckamp, W. N.; Hiemstra, H. Org. Lett. 1999, 1, 1331.
CH -CH), 2.26 [s, minor isomer, -C(O)-CH ] 2.28–2.36 [m,
2
3
2
2
H, -C(O)CH -CH ], 2.29 [s, major isomer, -C(O)-CH ],
.79 (s, minor isomer, -NCH ), 2.80 (s, major isomer,
2
2
3
3
-
NCH ), 3.72 [d, minor isomer, -C(O)-CH-C(O), J = 2.5
3
Hz), 3.82 [d, major isomer, -C(O)-CH-C(O), J = 3.0 Hz],
(
12) Abraham, T. W.; Leete, E. J. Labelled Compd. Radiopharm.
1996, 38, 419.
1
3
4.18–4.28 (m, 2 H, -O-CH -CH ). C NMR (75 MHz,
2 3
CDCl ): d = 14.0 [C(O)-OCH -CH ], 22.7 [-C(O)-CH -
3
2
3
2
CH -CH], 28.4 (N-CH ), 29.4 [-C(O)-CH -CH ], 29.9
2
3
2
2
Synlett 2003, No. 8, 1189–1191 ISSN 1234-567-89 © Thieme Stuttgart · New York