4862
S. Gowrisankar et al. / Tetrahedron Letters 46 (2005) 4859–4863
3. For the usefulness of 2,5-dihydrofurans and 2,5-dihydro-
pyrroles as synthetic intermediates, see (a) Morita, N.;
Krause, N. Org. Lett. 2004, 6, 4121; (b) Ajamian, A.;
Gleason, J. L. Org. Lett. 2001, 3, 4161.
Compound 5c: 56%; viscous oil; IR (neat) 2958, 2850, 1489,
1
1092 cmÀ1; H NMR (CDCl3) d 3.47 (s, 2H), 4.09 (s, 2H),
4.45–4.49 (m, 2H), 4.77–4.81 (m, 2H), 7.11 (d, J = 8.4 Hz,
2H), 7.27 (d, J = 8.4 Hz, 2H); 13C NMR (CDCl3) d 22.99,
30.90, 77.20, 78.03, 128.88, 129.52, 129.76, 132.58, 135.78,
136.53.
4. For the synthesis of 2,5-dihydrofuran and 2,5-dihydropyr-
role derivatives by ring-closing metathesis reaction, see (a)
Furstner, A.; Ackermann, L.; Gabor, B.; Goddard, R.;
Lehmann, C. W.; Mynott, R.; Stelzer, F.; Thiel, O. R.
Chem. Eur. J. 2001, 3236; (b) Terada, Y.; Arisawa, M.;
Nishida, A. Angew. Chem., Int. Ed. 2004, 43, 4063; (c)
Kitamura, T.; Sato, Y.; Mori, M. Adv. Synth. Catal. 2002,
344, 678; (d) Kitamura, T.; Kuzuba, Y.; Sato, Y.;
Wakamatsu, H.; Fujita, P.; Mori, M. Tetrahedron 2004,
60, 7375; (e) Michrowska, A.; Bujok, R.; Harutyunyan, S.;
Sashuk, V.; Dolgonos, G.; Grela, K. J. Am. Chem. Soc.
2004, 126, 9318; (f) Balan, D.; Adolfsson, H. Tetrahedron
Lett. 2004, 45, 3089; (g) Yang, C.; Murray, W. V.; Wilson,
L. J. Tetrahedron Lett. 2003, 44, 1783; (h) Wakamatsu, H.;
Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 2403.
5. For the synthesis of 2,5-dihydrofuran or 2,5-dihydropyrrole
derivatives by other means, see (a) Chou, W.-N.; White, J.
B. Tetrahedron Lett. 1991, 32, 7637; (b) Garsten, G.;
Mattay, J. Tetrahedron 1997, 53, 14297; (c) DeShong, P.;
Kell, D. A.; Sidler, D. R. J. Org. Chem. 1985, 50, 2309; (d)
Kang, S.-K.; Ko, B.-S.; Lee, D.-M. Tetrahedron Lett. 2002,
43, 6693; (e) Ma, S.; Yu, F.; Gao, W. J. Org. Chem. 2003,
68, 5943; (f) Ma, S.; Gao, W. J. Org. Chem. 2002, 67, 6104;
(g) Trost, B. M.; Rudd, M. T. J. Am. Chem. Soc. 2003, 125,
11516; (h) Duffy, M. G.; Grayson, D. H. J. Chem. Soc.,
Perkin Trans. 1 2002, 1555; (i) Donohoe, T. J.; Calabrese,
A. A.; Guillermin, J.-B.; Frampton, C. S.; Walter, D. J.
Chem. Soc., Perkin Trans. 1 2002, 1748; (j) Krause, N.;
Hoffmann-Roder, A.; Canisius, J. Synthesis 2002, 1759; (k)
Tiecco, M.; Testaferri, L.; Santi, C. Eur. J. Org. Chem.
1999, 797; (l) Xu, Z.; Lu, X. Tetrahedron Lett. 1997, 38,
3461; (m) Xu, Z.; Lu, X. J. Org. Chem. 1998, 63, 5031; (n)
Hoffmann-Roder, A.; Krause, N. Org. Lett. 2001, 3, 2537;
(o) Madhushaw, R. J.; Li, C.-L.; Su, H.-L.; Hu, C.-C.;
Lush, S.-F.; Liu, R.-S. J. Org. Chem. 2003, 68, 1872, and
further references cited therein.
Compound 5d: 56%; viscous oil; IR (neat) 2966, 2839, 1670,
1
1493, 1072 cmÀ1; H NMR (CDCl3) d 1.32 (d, J = 6.6 Hz,
3H), 3.39 (d, J = 15.3 Hz, 1H), 3.47 (d, J = 15.3 Hz, 1H),
3.82 (d, J = 9.9 Hz, 1H), 4.09 (d, J = 9.9 Hz, 1H), 4.19–4.37
(m, 2H), 5.02–5.14 (m, 1H), 7.16–7.33 (m, 5H); 13C NMR
(CDCl3) d À4.54, 20.48, 32.07, 76.54, 83.24, 126.62, 128.47,
128.71, 133.57, 135.97, 137.28.
Compound 5e: 65%; viscous oil; IR (neat) 2920, 2854, 1342,
1
1161 cmÀ1; H NMR (CDCl3) d 2.43 (s, 3H), 3.31 (s, 2H),
3.79 (s, 2H), 3.89 (s, 2H), 4.30 (s, 2H), 7.00–7.03 (m, 2H),
7.23–7.29 (m, 5H), 7.63 (d, J = 8.1 Hz, 2H); 13C NMR
(CDCl3) d À4.29, 21.52, 32.77, 56.77, 57.71, 126.77, 127.39,
128.42, 128.74, 129.22, 129.78, 133.83, 134.50, 136.57,
143.50.
Compound 5f: 70%; viscous oil; IR (neat) 2920, 1597, 1342,
1
1160 cmÀ1; H NMR (CDCl3) d 2.42 (s, 3H), 3.36 (s, 2H),
3.93 (s, 2H), 3.99 (s, 2H), 4.27 (s, 2H), 6.98–7.02 (m, 2H),
7.21–7.28 (m, 5H), 7.62 (d, J = 8.1 Hz, 2H); 13C NMR
(CDCl3) d 21.47, 23.86, 32.54, 56.33, 57.33, 126.76, 127.32,
128.18, 128.30, 128.70, 129.74, 133.74, 136.08, 136.58,
143.48.
1
Compound 4a: viscous oil; IR (neat) 3032, 1701 cmÀ1; H
NMR (CDCl3) d 2.92 (d, J = 13.8 Hz, 1H), 3.37 (d,
J = 13.8 Hz, 1H), 3.90 (d, J = 9.3 Hz, 1H), 4.22 (d, J =
9.3 Hz, 1H), 4.40 (d, J = 2.4 Hz, 1H), 4.42 (d, J = 2.4 Hz,
1H), 5.19 (t, J = 1.8 Hz, 1H), 5.40 (t, J = 2.1 Hz, 1H), 7.18–
7.27 (m, 5H), 10.67 (br s, 1H); 13C NMR (CDCl3) d 42.25,
57.90, 71.82, 73.89, 107.58, 127.18, 128.63, 129.93, 137.02,
149.73, 178.51.
Compound 4b: white solid, mp 72–75 °C; IR (neat) 2993,
1
1701 cmÀ1; H NMR (CDCl3) d 2.90 (d, J = 13.8 Hz, 1H),
3.31 (d, J = 13.8 Hz, 1H), 3.88 (d, J = 9.6 Hz, 1H), 4.22 (d,
J = 9.6 Hz, 1H), 4.40 (d, J = 2.4 Hz, 1H), 4.42 (d, J =
2.4 Hz, 1H), 5.20 (t, J = 2.0 Hz, 1H), 5.37 (t, J = 2.2 Hz,
1H), 7.14 (d, J = 8.4 Hz, 2H), 7.24 (d, J = 8.4 Hz, 2H),
11.33 (br s, 1H); 13C NMR (CDCl3) d 41.24, 57.56, 71.56,
73.59, 107.55, 128.54, 131.09, 132.94, 135.19, 149.20,
178.10.
6. (a) Shanmugam, P.; Rajasingh, P. Tetrahedron 2004, 60,
9283; (b) Shanmugam, P.; Rajasingh, P. Chem. Lett. 2002,
1212; (c) Shanmugam, P.; Rajasingh, P. Synlett 2005, 939;
(d) Shanmugam, P.; Rajasingh, P. Tetrahedron Lett. 2005,
46, 3369; Recently, Roy and co-workers reported the
synthesis of methylene tetrahydrofurans via radical cycli-
zation: please see Jana, S.; Guin, C.; Roy, S. C. Tetrahedron
Lett. 2005, 46, 1155.
7. Starting materials 2b,c and e were synthesized similarly.6
Synthesis of 2d was carried out via two steps: introduction
of tosylamide by the reaction of the corresponding Baylis–
Hillman acetate and tosylamide in the presence of K2CO3
in DMF, propargylation with propargyl bromide with
K2CO3 in DMF.1
1
Compound 4c: viscous oil; IR (neat) 2978, 1697 cmÀ1; H
NMR (CDCl3) d 1.35 (d, J = 6.3 Hz, 3H), 2.91 (d,
J = 13.8 Hz, 1H), 3.28 (d, J = 13.8 Hz, 1H), 4.01 (d,
J = 9.6 Hz, 1H), 4.08 (d, J = 9.6 Hz, 1H), 4.42–4.50 (m,
1H), 5.08 (d, J = 2.4 Hz, 1H), 5.36 (d, J = 2.1 Hz, 1H),
7.20–7.30 (m, 5H), 9.86 (br s, 1H); 13C NMR (CDCl3) d
19.95, 42.77, 58.22, 71.02, 77.85, 107.35, 126.94, 128.33,
130.03, 136.88, 154.45, 178.35.
Compound 4d: white solid, mp 51–53 °C; IR (neat) 3032,
1705, 1161 cmÀ1; 1H NMR (CDCl3) d 2.42 (s, 3H), 2.92 (d,
J = 13.8 Hz, 1H), 3.28 (d, J = 13.8 Hz, 1H), 3.37 (d, J =
9.9 Hz, 1H), 3.44 (d, J = 9.9 Hz, 1H), 3.70 (d, J = 13.8 Hz,
1H), 4.02 (d, J = 13.8 Hz, 1H), 5.18 (s, 1H), 5.41 (s, 1H),
7.14–7.32 (m, 7H), 7.67 (d, J = 7.8 Hz, 2H), 10.15 (br s,
1H); 13C NMR(CDCl3) d 21.74, 42.67, 52.21, 53.03, 57.42,
110.52, 127.42, 128.15, 128.76, 129.90, 129.99, 132.13,
136.24, 144.15, 145.62, 177.67.
8. Synthesis of 3 was carried out according to the reported
method.6 Hydrolysis of 3 to 4 and halolactonization of 4
was carried out according to the general procedures as
shown in the footnotes of Table 1. Selected spectroscopic
data of 5a–f, 4a–d, and 7–11 are as follows:
Compound 5a: 41%; viscous oil; 1H NMR (CDCl3) d
3.44 (s, 2H), 4.00 (s, 2H), 4.32–4.36 (m, 2H), 4.78–4.83
(m, 2H), 7.16–7.33 (m, 5H); 13C NMR (CDCl3) d À4.92,
31.77, 77.20, 78.55, 126.66, 128.50, 128.73, 129.87, 135.58,
137.28.
Compound 7: 70%; viscous oil; 1H NMR (CDCl3) d 1.85 (d,
J = 0.9 Hz, 3H), 2.41 (s, 3H), 3.66 (s, 2H), 6.80 (s, 1H), 6.90
(d, J = 0.9 Hz, 1 H), 7.10 (d, J = 8.4 Hz, 2H), 7.18–7.31 (m,
5H), 7.70 (d, J = 8.4 Hz, 2H).
Compound 5b: 48%; viscous oil; IR (neat) 2846, 1061 cmÀ1
;
1H NMR (CDCl3) d 3.50 (s, 2H), 4.11 (s, 2H), 4.47–4.51 (m,
2H), 4.77–4.81 (m, 2H), 7.15–7.33 (m, 5H); 13C NMR
(CDCl3) d 23.29, 31.56, 77.05, 78.20, 126.69, 128.41, 128.73,
128.97, 137.15, 137.34.
Compound 8: 80%; viscous oil; 1H NMR (CDCl3) d 3.85 (s,
2H), 4.18 (s, 2H), 7.14 (s, 1H), 7.19–7.33 (m, 5H), 7.45 (s,
1H); 13C NMR (CDCl3) d 22.82, 29.53, 121.97, 123.87,
126.41, 128.53, 128.59, 139.11, 141.46, 142.11.