14 (a) A. Basak, U. K. Khamrai and U. K. Mallick, Chem. Commun.,
1996, 749–750; (b) A. Basak and S. Mandal, Tetrahedron Lett., 2002, 43,
4241–4243; (c) A. Basak, U. K. Khamrai and J. C. Shain, Tetrahedron
Lett., 1997, 38, 6067–6070.
15 S. C. Ghosh and A. Basak, Tetrahedron Lett., 2005, 26, 7385–7389.
16 (a) K. Sonogashira, Y. Tohoda and N. Hagihara, Tetrahedron Lett.,
1975, 50, 4467–4470; (b) S. Takahashi, Y. Kuroyama, K. Sonogashira
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OH, undergoes elimination under the reaction conditions which
cannot happen for the major isomer 5.
In conclusion, we have successfully developed a general
synthetic route to b-lactam-fused enediynes by an intramolecular
Kinugasa reaction. The method has widened the scope of the
Kinugasa reaction in the synthesis of sensitive systems like the one
described in this communication. The mechanism of formation of
an elimination product was also successfully established.
A. B. thanks DST, Government of India for a research grant.
R. P. is grateful to CSIR, Government of India for a senior
research fellowship.
17 A. Basak, H. M. Bdour and G. Bhattacharya, Tetrahedron Lett., 1997,
38, 2535–2538.
1
18 Selected spectral data (all H and 13C NMR were recorded at 200 and
50 MHz, respectively, in CDCl3 unless mentioned otherwise). For 1: dH
(d6-acetone): 7.38–7.22 (9H, m), 4.63, 4.41 (2H, ABq, J = 15.6 Hz), 4.71,
4.52 (2H, ABq, J = 17.1 Hz), 4.27 (2H, d, J = 4.45 Hz), 3.86–3.70 (2H,
m), 2.63–2.12 (4H, m); dC 167.6, 135.8, 130.5, 130.1, 128.8, 128.0, 127.9,
127.7, 127.5, 126.3, 126.0, 94.2, 89.3, 86.7, 80.8, 64.2, 58.9, 55.4, 52.6,
44.3, 26.3, 16.2; HRMS: calc. for C24H21NO2 + H+ 356.1651, found
356.1653. For 2: dH 7.38–7.12 (9H, m), 4.60, 4.25 (2H, ABq, J =
16.9 Hz), 4.46, 4.36 (2H, ABq, J = 15.6 Hz), 4.17–4.14 (1H, m), 4.07–
4.03 (2H, m), 3.06–3.04 (1H, m), 2.58–2.43 (2H, m), 1.91–1.83 (2H, m);
dC 167.1, 136.0, 131.3, 130.7, 128.4, 127.8, 127.7, 127.5, 127.3, 125.4,
125.2, 91.1, 89.0, 85.0, 81.1, 64.2, 58.7, 54.9, 53.7, 44.6, 29.4, 16.0;
HRMS: calc. for C24H21NO2 + H+ 356.1651, found 356.1642. For 3: dH
7.38–7.19 (9H, m), 4.53, 4.22 (2H, ABq, J = 15.5 Hz), 4.45, 4.30 (2H, d,
J = 18.3 Hz), 3.96–3.81 (2H, m), 3.68–3.53 (2H, m), 2.67–2.50 (1H, m),
2.36–1.63 (5H, m); dC 169.1, 131.2, 130.9, 128.5, 128.4, 127.6, 127.6,
127.6, 127.3, 127.2, 125.4, 92.2, 89.1, 85.0, 81.1, 67.8, 58.8, 55.1, 50.1,
44.1, 26.9, 24.5, 16.9; HRMS: calc. for C25H23NO2 + H+ 370.1808,
found 370.1793. For 4: dH 7.39–7.20 (9H, m), 4.46, 4.30 (2H, ABq, J =
15.3 Hz), 4.44, 4.28 (2H, d, J = 16.3 Hz), 4.17–4.05 (2H, m), 3.85–3.79
(1H, m), 3.55–3.50 (1H, m), 2.90–2.82 (1H, m), 2.53–1.90 (6H, m); dC
169.7, 136.5, 131.7, 131.2, 128.8, 128.7, 128.1, 127.6, 127.0, 126.4, 125.4,
93.0, 92.2, 88.7, 66.8, 58.4, 57.5, 52.7, 44.9, 31.0, 27.6, 16.3; HRMS: calc.
for C25H23NO2 + H+ 370.1808, found 370.1821. For 5: dH 7.38–7.23
(9H, m), 4.89 ( 1H, d, J = 10 Hz), 4.71, 4.08 (2H, ABq, J = 15.0 Hz),
3.51 (1H, m), 3.36 (1H, dd, J = 2.5 Hz), 2.65–2.25 (4H, m); dC 168.2,
134.9, 129.7, 129.5, 129.1, 128.2, 128.1, 127.6, 127.3, 125.7, 93.5, 92.0,
81.0, 85.5, 63.6, 63.0, 55.5, 44.0, 30.00, 18.1; HRMS: calc. for
C23H19NO2 + H+ 342.1495, found 342.1526. For 6: dH 7.44–7.20 (9H,
m), 6.28 (1H, d, J = 1.5 Hz), 4.82, 4.20 (2H, ABq, J = 15.0 Hz), 3.98
(1H, m), 2.63–2.56 (2H, m), 2.19–1.97 (2H, m); dC 167.3, 154.6, 134.7,
130.0, 129.4, 130.0, 128.8, 128.4, 128.1, 127.6, 126.4, 104.0, 96.6, 96.3,
89.7, 80.9, 60.9, 44.3, 28.8, 19.9; HRMS: calc. for C23H17NO + H+
324.1389, found 324.1429.
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2994 | Chem. Commun., 2006, 2992–2994
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