3 L. El Kaim, L. Grimaud, L. D. Miranda and E. Vieu, Tetrahedron
Lett., 2006, 47, 8259.
358.1385, found 358.1380. Typical experimental procedure given
for radical cyclization of 1b: to a degassed solution of xanthate
adduct 1b (0.5 mmol) in isopropanol (25 ml) heated at reflux under
argon was added dilauroyl peroxide (0.5 mmol) and the mixture
was heated for 16 h. Removal of the solvent and purification
by flash column chromatography on silica gel (petroleum
ether–diethyl ether, 30 : 70) gave 2b (88% yield) as a yellow oil.
1H NMR (CDCl3, 400 MHz) d 5.88 (br s, 1H), 5.13 (pent., 2H, J =
2.4 Hz), 4.39 (t, 1H, J = 7.5 Hz), 4.14 (dd, 1H, J = 2.4, 14.2 Hz),
4.02 (dd, 1H, J = 2.4, 14.2 Hz), 3.20–3.18 (m, 2H), 1.96–1.93 (m,
1H), 1.70–1.68 (m, 1H), 1.29 (s, 9H), 0.92 (t, 3H, J = 7.4 Hz).13C
NMR (CDCl3, 100.6 MHz) d 173.95, 169.26, 136.92, 110.05, 57.44,
51.81, 49.92, 37.97, 29.10, 21.54, 11.89. IR (thin film) 2945, 1678,
1543, 1456, 1230, 1012 cmÀ1. HRMS calcd. 238.1681, found
238.1678.
4 D. P. Curran, M. H. Chen and D. Kim, J. Am. Chem. Soc., 1989,
111, 6265; D. P. Curran and C.-T. Chang, J. Org. Chem., 1989, 54,
3140; R. Yanada, Y. Koh, N. Nishimori, A. Matsumura, S. Obika,
H. Mitsuya, N. Fujii and Y. Takemoto, J. Org. Chem., 2004, 69,
2417.
5 J. H. Udding, K. C. J. M. Tuijp, M. N. A. vanZenden, H. Hiemstra
and W. N. Speckamp, J. Org. Chem., 1994, 59, 1993; A. J. Clark,
G. M. Battle and A. Bridge, Tetrahedron Lett., 2001, 42, 1999.
6 L. Engman and V. Gupta, J. Org. Chem., 1997, 62, 157.
7 For some reactions of alkenyl radicals see: F. Denes, F. Beaufils
´
and P. Renaud, Org. Lett., 2007, 9, 4375; N. J. Bennett,
J. C. Prodger and G. Pattenden, Tetrahedron, 2007, 63, 6216;
D. Melandri, P. C. Montevecchi and M. L. Navacchia, Tetra-
hedron, 1999, 55, 12227; R. Andrukiewicz, R. Loska,
V. Prisyahnyuk and K. Stalinski, J. Org. Chem., 2003, 68, 1552.
8 A. Liard, B. Quiclet-Sire and S. Z. Zard, Tetrahedron Lett., 1996,
37, 5877.
10 M. S. M. Timmer, M. D. P. Risseeuw, M. Verdoes, D. V. Filipov,
J. R. Plaisier, G. A. van der Marel, H. S. Overkleeft and J. H. van
Boom, Tetrahedron: Asymmetry, 2005, 16, 177.
11 F. Gagosz and S. Z. Zard, Org. Lett., 2003, 5, 2655; F. Barbier,
F. Pautrat, B. Quiclet-Sire, B. Sortais and S. Z. Zard, Synlett, 2002,
811; B. Quiclet-Sire, B. Sortais and S. Z. Zard, Chem. Commun.,
2002, 1692; G. Binot and S. Z. Zard, Tetrahedron Lett., 2005, 46,
7503; N. Cholleton and S. Z. Zard, Tetrahedron Lett., 1998, 39,
9 Typical experimental procedure given for xanthate 1b: to
a
1 M solution of propionaldehyde (1 mmol) in methanol were
successively added propargylamine (1 mmol), chloroacetic acid
(1 mmol) and tert-butylisocyanide (1 mmol). The resulting mixture
was stirred at room temperature for 16 h. Then, potassium
O-ethylxanthogenate was added and the reaction mixture was
stirred at room temperature for 3 h. Extraction, removal of the
solvent, and purification by flash column chromatography on silica
gel (petroleum ether–diethyl ether, 30 : 70) gave 1b (70% yield) as a
yellow oil. 1H NMR (CDCl3, 400 MHz) d 5.98 (br s, 1H, NH), 4.82
(t, 1H, J = 8.1 Hz), 4.65 (q, 2H, J = 7.1 Hz), 4.31 (d, 1H, J =
16.1 Hz), 4.30 (dd, 2H, J = 2.4, 9.0 Hz), 4.11 (d, 1H, J = 16.1 Hz),
2.38 (t, 1H, J = 2.4 Hz), 1.98–1.95 (m, 1H), 1.76–1.74 (m, 1H),
1.38 (t, 3H, J = 7.1 Hz), 1.32 (s, 9H), 0.91 (t, 3H, J = 7.4 Hz).13C
NMR (CDCl3, 100.6 MHz) d 214.58, 169.43, 168.70, 79.37, 73.74,
70.83, 59.98, 52.01, 39.54, 35.05, 29.02, 21.90, 14.18, 11.07. IR (thin
film) 3267, 2964, 1645, 1382, 1187, 1086 cmÀ1. HRMS calcd.
7295; E. Bacque, M. El Qacemi and S. Z. Zard, Org. Lett., 2004, 6,
´
3671; A. Cordero-Vargas, B. Quiclet-Sire and S. Z. Zard, Org.
Biomol. Chem., 2005, 3, 4432; Y. M. Osornio, R. Cruz-Almanza,
V. Jimenez-Montano and L. D. Miranda, Chem. Commun., 2003,
2316.
12 For some reviews, see: A. Domling and I. Ugi, Angew. Chem., Int.
¨
Ed., 2000, 39, 3168; H. Bienayme
P. Schmitt, Chem.–Eur. J., 2000, 6, 3321; I. Ugi, B. Werner and
A. Domling, Molecules, 2003, 8, 53; A. Domling, Curr. Opin.
´
, C. Hulme, G. Oddon and
¨
¨
Chem. Biol., 2002, 6, 306; Multicomponent Reactions, ed. J. Zhu
and H. Bienayme, Wiley-VCH, Weinheim, 2005; A. Domling,
Chem. Rev., 2006, 106, 17–89.
´
¨
13 L. El Kaim, L. Grimaud and E. Vieu, Org. Lett., 2007, 9, 4171.
ꢁc
This journal is The Royal Society of Chemistry 2010
Chem. Commun., 2010, 46, 2489–2491 | 2491