P. Quadrelli, V. Fassardi, A. Cardarelli, P. Caramella
FULL PAPER
L. Boger, S. M. Weinreb, Hetero-DielsϪAlder Methodology in
Organic Synthesis, Academic Press: San Diego, 1987.
9.0 Hz, 1 H, 3a-H), 4.89 (t, J ϭ 6.0 Hz, 1 H, CHϪN), 5.20 (dd,
J ϭ 9, 1.5 Hz, 1 H, 6a-H), 5.53 (d, J ϭ 4.4 Hz, 1 H, CHϪO), 6.91
(br. d, J ϭ 8.4 Hz, 1 H, NH), 7.4Ϫ7.6 (m, 6 H, arom.), 7.80 (m, 2
H, arom.), 7.95 (m, 2 H, arom.) ppm. 13C NMR: δ ϭ 21.0
(CH3CO), 34.8 (CH2), 55.3 (3a-CH), 60.2 (CHϪN), 80.7 (CHϪO),
88.9 (6a-CH), 126.5, 127.4, 127.8, 128.7, 128.8, 130.3, 131.8, 133.9
(C-arom.), 156.2 (CϭN), 166.4, 168.4 (CϭO) ppm. C21H20N2O4
(364.4): calcd. C 69.21, H 5.53, N 7.69; found C 69.1, H 5.5, N 7.6.
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G. E. Keck, S. A. Fleming, Tetrahedron Lett. 1978,
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P. Quadrelli, M. Mella, P. Paganoni, P. Caramella, Eur. J. Org.
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P.Quadrelli, V. Fassardi, A. Cardarelli, P. Caramella, Proceed-
ings of the Pericyclic Reactions Symposium, Naples (Italy),
24Ϫ25th September 2001, p. 13.
Compound 10b: M.p. 134Ϫ135 °C from ethyl acetate. IR: ν˜ ϭ 1640
1
(NCϭO), 1740 (CϭO), 3331 (NH) cmϪ1. H NMR: δ ϭ 2.05 (m,
[5] [5a]
M. Cowart, M. J. Bennett, J. F. Kerwin Jr., J. Org. Chem.
1 H, CH2), 2.19 (m, 1 H, CH2), 2.20 (s, 1 H, COCH3), 4.31 (dd,
J ϭ 9, 1 Hz, 1 H, 3a-H), 4.99 (dd, J ϭ 8.4, 7.3 Hz, 1 H, CHϪN),
5.26 (d, J ϭ 9.0 Hz, 1 H, 6a-H), 5.49 (d, J ϭ 4.5 Hz, 1 H, CHϪO),
6.78 (br. d, J ϭ 8.4 Hz, 1 H, NH), 7.4Ϫ7.6 (m, 6 H, arom.), 7.79
(m, 2 H, arom.), 7.90 (m, 2 H, arom.) ppm. 13C NMR: δ ϭ 21.1
(CH3CO), 34.9 (CH2), 57.2 (3a-CH), 58.9 (CHϪN), 79.5 (CHϪO),
90.7 (6a-CH), 126.5, 127.0, 127.9, 128.6, 128.7, 130.2, 131.6, 134.0
(C-arom.), 154.6 (CϭN), 166.0, 169.0 (CϭO) ppm. C21H20N2O4
(364.4): calcd. C 69.21, H 5.53, N 7.69; found C 69.2, H 5.5, N 7.7.
[5b]
1999, 64, 2240Ϫ2249.
M. T. Crimmins, Tetrahedron 1998,
54, 9229Ϫ9272. [5c] L. Agrofoglio, E. Suhas, A. Farese, R. Con-
dom, S. R. Challand, R. A. Earl, R. Guedj, Tetrahedron 1994,
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ron 1992, 48, 571Ϫ623.
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A. H. Hoveyda, D. A. Evans, G. C. Fu, Chem. Rev. 1993, 93,
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P. Caramella, P. Grünanger, 1,3-Dipolar Cycloaddition Chem-
istry (Ed.: A. Padwa); John Wiley and Sons, Inc. New York,
1984; vol. 1, pp. 291Ϫ392.
Compound 10d: M.p. 175Ϫ176 °C from ethanol. IR: ν˜ ϭ 1632
Allylic OH directive effects: [8a] P. Caramella, G. Cellerino, Tet-
[8]
1
(NCϭO), 1745 (CϭO), 3335 (NH) cmϪ1. H NMR: δ ϭ 1.34 (s, 1
[8b]
rahedron Lett. 1974, 229Ϫ232.
C. De Micheli, A. Gamba,
[8c]
H, COCH3), 1.88 (m, 1 H, CH2), 2.49 (m, 1 H, CH2), 4.46 (t, J ϭ
8.0 Hz, 1 H, 3a-H), 4.79 (m, 1 H, CHϪN), 5.19 (dd, J ϭ 8, 5 Hz,
1 H, 6a-H), 5.48 (m, 1 H, CHϪO), 6.74 (br. d, J ϭ 8.0 Hz, 1 H,
NH), 7.4Ϫ7.7 (m, 8 H, arom.), 7.85 (m, 2 H, arom.) ppm. 13C
NMR: δ ϭ 19.8 (CH3CO), 33.4 (CH2), 50.3 (3a-CH), 52.6
(CHϪN), 72.0 (CHϪO), 86.1 (6a-CH), 126.9, 127.0, 128.5, 129.7,
129.8, 131.7, 133.8, (C-arom.), 157.4 (CϭN), 167.1, 170.2 (CϭO)
ppm. C21H20N2O4 (364.4): calcd. C 69.21, H 5.53, N 7.69; found
C 69.1, H 5.6, N 7.7.
R. Gandolfi, L. Scevola, Chem. Commun. 1976, 246Ϫ247.
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1875Ϫ1818.
[9]
[9a]
Allylic NHCOR directive effects:
F. Marinone Albini, D.
Vitali, R. Oberti, P. Caramella, J. Chem. Res. (S) 1980, 348;
F. Marinone Albini, D. Vitali, R. Oberti, P. Caramella, J.
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Chem. Res. (M) 1980, 4355Ϫ4384.
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21, 949Ϫ952.
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D. P.
Acylation of cycloadducts 3a/3b/3d by the same procedure (Ac2O,
Et3N, DMAP, room temp. 2 h) as used for the preparation of 9
provided samples of compounds 10a/10b/10d identical to the prod-
ucts described above.
[9e]
55, 3710Ϫ3712.
D. P. Curran, S. A. Gothe, S. M. Choi,
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C. Reichardt, Solvents and Solvent Effects in Organic
Chemistry, VCH-Verlagsgesellschaft, Weinheim, 1988, p. 392.
A sample of 10d was quantitatively cleaved to afford 3d by addition
of solid NaOH (0.1 g) to a solution of 10d (0.05 g) in methanol
(20 mL). After the mixture had been stirred for 2 h at room temp.,
the solvent was evaporated and the residue was taken up with water
and chloroform. The organic phase was dried with Na2SO4, and
the solvents were evaporated to leave 3d, identical to the product
described above.
[10b]
C. Reichardt, Chem. Rev. 1994, 94, 2319Ϫ2358, and refer-
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O. Exner, Correlation Analysis in Chemistry (Eds.: N. B. Chap-
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Solvent Effect and HPLC Determinations: The dipolarophiles 2 and
8 (1.2 equiv.) were dissolved in the desired solvent (25 mL) and
benzhydroximoyl chloride (1 equiv.), the precursor of BNO, was
added to the solution, followed by Et3N (1.2 equiv.). The mixtures
were stirred for 2 days until complete consume of the 1,3-dipole.
The reaction mixtures were evaporated to dryness, taken up with
acetonitrile and submitted to HPLC analyses for quantitative deter-
mination. Yields and regioisomeric ratios were determined by suit-
able internal standard methods.
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Acknowledgments
Financial support by University of Pavia (FAR), the MURST
(PRIN 2000) and the CNR is gratefully acknowledged.
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