LETTER
Chem. 2008, 51, 6110. (f) Gaumont, A.-C.; Gulea, M.;
Ethyl Z-2-(2-substituted-thiazol-4-yl)pent-2-enoates
1403
in CH2Cl2 (15 mL). To the solution was added a solution of
3 (5.0 mmol) in DMF (15 mL) at 0 °C, and then the mixture
was stirred at the same temperature for the specified reaction
time (t, see text). Thereafter, aq NaHCO3 (8%, 20 mL) was
rapidly added to the mixture. The organic layer was
separated, and the aq phase was extracted with CH2Cl2 (2 ×
25 mL). The combined organic phase was washed with sat.
brine (60 mL), dried over anhyd Na2SO4. The filtrate was
concentrated to give the crude product, which was purified
by column chromatography to give 4 and 5 in corresponding
yields.
Levillain, J. Chem. Rev. 2009, 109, 1371. (g) Quin, L. D.;
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P.; Sreedhar, G.; Kamma, R. IN 2007CH00299A, 2008;
Chem. Abstr. 2008, 150, 329477 (g) Gedi, S.; Ramakrishna,
K.; Udayampalayam, P. S. WO 2008155615A2, 2008;
Chem. Abstr. 2008, 150, 77403
Analytical Data for Representative Compounds 4a and
5a
Compound 4a: yellow solid, mp 74–76 °C, 0.53 g (47%,
neutralizing treatment at 30 min), 0.48 g (42%, t = 2 h). 1H
NMR (400 MHz, CDCl3): δ = 1.07 (t, J = 7.6 Hz, 3 H), 1.34
(t, J = 7.2 Hz, 3 H), 2.35 (quint, J = 7.6 Hz, 2 H), 4.30 (q, J
= 7.2 Hz, 2 H), 5.26 (br s, 2 H), 6.50 (s, 1 H), 6.69 (t, J = 7.6
Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 13.8, 14.3,
23.3, 60.8, 104.9, 128.2, 140.6, 147.2, 166.9, 167.6 ppm.
ESI-HRMS: m/z [M + H+] calcd for C10H15N2O2S: 227.0854;
found: 227.0854.
Compound 5a: yellow solid, mp 107–109 °C, 0.32 g (28%,
neutralizing treatment at 30 min), 0.41 g (36%, t = 2 h). 1H
NMR (400 MHz, CDCl3): δ = 1.04 (t, J = 7.6 Hz, 3 H), 1.27
(t, J = 7.2 Hz, 3 H), 2.31 (quint, J = 7.6 Hz, 2 H), 4.21 (q, J
= 7.2 Hz, 2 H), 5.22 (br s, 2 H), 6.42 (s, 1 H), 6.98 (t, J = 7.6
Hz, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 13.4, 14.2,
23.2, 60.9, 108.0, 127.7, 145.0, 148.4, 166.7, 166.8 ppm.
ESI-HRMS: m/z [M + H+] calcd for C10H15N2O2S: 227.0854;
found: 227.0854.
(12) The configurations of all compounds 4 and 5 were
determined by 1H-1H NOESY except 4b, 4c, and 5c for their
unstability.
(13) (a) Arakawa, K.; Miyasaka, T.; Ohtsuka, H. Chem. Pharm.
Bull. 1972, 20, 1041. (b) Challacombe, K.; Plackett, S. J.;
Meakins, G. D. Tetrahedron Lett. 1987, 28, 5767. (c) Qiao,
Q.; So, S.-S.; Goodnow, R. A. Jr. Org. Lett. 2001, 3, 3655.
(d) Ochiai, M.; Nishi, Y.; Hashimoto, S.; Tsuchimoto, Y.;
Chen, D.-W. J. Org. Chem. 2003, 68, 7887. (e) Yavari, I.;
Sayyed-Alangi, S. Z.; Hajinasiri, R.; Sajjadi-Ghotbabadi, H.
Monatsh. Chem. 2009, 140, 209.
(14) Preparation Procedure for the New Route to 6
Firstly, the material (E/Z)-2 (2.49 g, 10.0 mmol) were
dissolved in CH2Cl2 (20 mL). To the solution was added a
solution of N-tert-butoxycarbonylthiourea (3e, 1.76 g, 10.0
mmol) in DMF (20 mL) at 0 °C, and then stirred for 30 min
at 0 °C. Then, aq NaHCO3 (8%, 40 mL) was rapidly added
to the mixture. The organic layer was separated, and the
aqueous phase was extracted with CH2Cl2 (2 × 50 mL). The
combined organic phase was washed with sat. brine (100
mL), and dried over anhyd Na2SO4. The filtrate was
concentrated to afford the crude product, which was purified
by column chromatography on silica gel (EtOAc–PE, 1:25)
to give 4e and 5e.
(5) Ishikura, K.; Kubota, T.; Minami, K.; Hamashima, Y.;
Nakashimizu, H.; Motokawa, K.; Kimura, Y.; Miwa, H.;
Yoshida, T. J. Antibiotics 1994, 47, 466.
(6) Jiang, J.-A.; Zhai, J.-J.; Yu, X.-H.; Teng, X.; Ji, Y.-F.
Synthesis 2012, 44, 207.
(7) Kubota, T.; Kume, M. EP 0467647, 1992; Chem. Abstr.
1992, 116, 235340
(8) (a) Bhatia, S. H.; Buckley, D. M.; Mccabe, R. W.; Avent, A.;
Brown, R. G.; Hitchcock, P. B. J. Chem. Soc., Perkin Trans.
1 1998, 569. (b) Anselmi, E.; Blazejewski, J.-C.;
Wakselman, C. J. Fluorine Chem. 2001, 107, 315.
(c) Antonioletti, R.; Bovicelli, P.; Malancona, S.
Tetrahedron 2002, 58, 589.
(9) 1H NMR analysis indicated the obtained (E/Z)-2 in a 1.0:1.4
ratio under the reaction temperature of –30 °C.
(10) It was shown that the reaction could be immediately stopped
by acid-binding agent. The reaction pathway was commonly
considered via a hydroxythiazoline intermediate. For the
hydroxythiazoline intermediates and their acid-promoted
dehydrations in Hantzsch thiazole synthesis, see:
(a) Lepeshkin, A. Y.; Turchin, K. F.; Sedov, A. L.;
Velezheva, V. S. Russ. Chem. Bull., Int. Ed. 2007, 56, 1441.
(b) Lepeshkin, A. Y.; Turchin, K. F.; Galpern, E. G.;
Stankevich, I. V.; Lyssenko, K. A.; Velezheva, V. S. Russ.
Chem. Bull., Int. Ed. 2007, 56, 1447.
Analytical Data for Compounds 4e and 5e
Compound 4e: pale yellow oil; yield: 2.77 g (85%). 1H NMR
(400 MHz, CDCl3): δ = 1.09 (t, J = 7.6 Hz, 3 H), 1.34 (t, J =
7.2 Hz, 3 H), 1.49 (s, 9 H), 2.41 (quint, J = 7.6 Hz, 2 H), 4.32
(q, J = 7.2 Hz, 2 H), 6.75 (t, J = 7.6 Hz, 1 H), 6.89 (s, 1 H),
9.06 (br s, 1 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 13.7,
14.3, 23.3, 28.1 (3 C), 60.8, 82.9 (w), 108.8, 127.8, 141.5,
146.1, 151.9 (w) 159.3, 167.3 ppm. ESI-HRMS: m/z [M +
H+] calcd for C15H23N2O4S: 327.1379; found: 327.1373.
Compound 5e: pale yellow solid; mp 69–71 °C; yield: 0.10
g (3%). 1H NMR (400 MHz, CDCl3): δ = 1.02 (t, J = 7.6 Hz,
3 H), 1.23 (t, J = 7.2 Hz, 3 H), 1.51 (s, 9 H), 2.30 (quint, J =
(11) General Procedure for the Synthesis of 4 and 5
The material (E/Z)-2 (1.25 g, 5.0 mmol) were first dissolved
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Synlett 2013, 24, 1399–1404