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LETTER
(4) (a) Shachat, N.; Bagnell, J. J. Org. Chem. 1963, 28, 991.
It is noteworthy that while most reactions proceeded with
virtually perfect regioselectivity and stereoselectivity, a
byproduct (iso-9b) resulting from a 6-endo cyclization
was formed (to an extent of ca. 17%) only in the case of
9b (Table 3; entries 3 and 4). In the case of 9f (see
Table 3, entry 12) a byproduct was observed (ca. 10%)
which was tentatively assigned as the corresponding E
isomer. We have no explanation why the selectivity is in-
complete in this case; however, we could at least exclude
a secondary isomerization of the initially formed Z-prod-
uct 9f under the reaction conditions.
(b) Stoffel, P. J.; Speziale, A. J. J. Org. Chem. 1963, 28,
2814.
(5) Müller, T. E.; Beller, M. Chem. Rev. 1998, 98, 675.
(6) (a) Kimura, M.; Kure, S.; Yoshida, Z.; Tanaka, S.; Fugami,
K.; Tamaru, Y. Tetrahedron Lett. 1990, 31, 4887.
(b) Tamaru, Y.; Kimura, M.; Tanaka, S.; Kure, S.; Yoshida,
Z. Bull. Chem. Soc. Jpn. 1994, 67, 2383. (c) Ohe, K.;
Matsuda, H.; Ishihara, T.; Chatani, N.; Kawasaki, Y.; Murai,
S. J. Org. Chem. 1991, 56, 2267. (d) For a related Pd-
catalyzed transformation, see: Lei, A.; Lu, X. Org. Lett.
2000, 2, 2699.
(7) For recent reviews on Au-catalysis, see: (a) Hashmi, A. S.
K. Gold Bull. 2004, 37, 51. (b) Hashmi, A. S. K. Angew.
Chem. Int. Ed. 2004, 44, 6990; Angew. Chem. 2005, 117,
7150. (c) Hoffmann-Röder, A.; Krause, N. Org. Biomol.
Chem. 2005, 3, 387.
(8) (a) Mizushima, E.; Hayashi, T.; Tanaka, M. Org. Lett. 2003,
5, 3349. (b) Alfonsi, M.; Arcadi, A.; Aschi, M.; Bianchi, G.;
Marinelli, F. J. Org. Chem. 2005, 70, 2265. (c) Gorin, D. J.;
Davis, N. R.; Toste, D. J. Am. Chem. Soc. 2005, 127, 11260.
(9) Braunstein, P.; Lehner, H.; Matt, D. Inorg. Synth. 1990, 27,
218.
(10) For the Au(III)-catalyzed intramolecular hydroamination of
simple aminoalkynes, see: (a) Fukuda, Y.; Utimoto, K.;
Nozaki, H. Heterocycles 1987, 25, 297. (b) Fukuda, Y.;
Utimoto, K. Synthesis 1991, 975. (c) For the first use of
AuCl3 in homogeneous catalysis, see: Hashmi, A. S. K.;
Schwarz, L.; Choi, J.-H.; Frost, T. M. Angew. Chem. Int. Ed.
2000, 39, 2285; Angew. Chem. 2000, 112, 2382.
To probe the proposed mechanism (Scheme 2) and its ste-
reochemical course (anti addition to the triple bond), the
AuCl-catalyzed cyclization of 6 to 7 was carried out in
deuterated methanol (CD3OD) as a solvent. Indeed, as
Equation 3 indicates, deuterium was incorporated only in
the E-position of the product 7¢ as determined by 1H NMR
analysis.
O
O
AuCl (5 mol%)
Et3N (5 mol%)
Ts
Ts
O
N
O
N
H
CD3OD, r.t., 1 h
93%
H (0% D)
D (76% D)
H
6
7'
Equation 3
(11) Crystal data for compound 9a: colorless crystals (from
cyclohexane); mp 87–88 °C; C16H19NO4S, FW = 321.10,
triclinic, space group P-1; a = 7.2854 (2) Å, b = 8.7222 (3)
Å, c = 12.7763 (4) Å; a = 96.866 (2)°, b = 100.075 (2)°, g =
99.598 (2)°; V = 778.85 (4) Å3; Z = 2; dcalc = 1.370 g/cm3;
R = 0.0391, Rw = 0.0837 for 2517 reflections having I >
2s(I). Further crystallographic data have been deposited at
the Cambridge Crystallographic Data Centre. Copies of the
data (CCDC 613241) can be obtained free of charge from
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax:
+44 (1223)336033; e-mail: deposit@ccdc.cam.ac.uk].
(12) Such a mechanism was previously proposed for a related
gold-catalyzed transformation (oxazole synthesis): Hashmi,
A. S. K.; Weyrauch, J. P.; Frey, W.; Bats, J. W. Org. Lett.
2004, 6, 4391.
(13) General Procedure for the AuCl-Catalyzed Cyclization
of O-Propargyl Carbamates: To a solution of an O-
propargyl carbamate (6 or 8a–8f; 0.5 mmol) and a base co-
catalyst (0.025 mol, 5 mol%) in solvent (2 mL) was added
AuCl (0.025 mol, 5 mol%). The mixture was stirred at r.t. or
60 °C for the time specified in Tables 2 and 3. Conversion
was monitored by TLC and/or GLC analyses. The reaction
mixture was filtered through a small pad of Celite® (elution
with CH2Cl2). Removal of the solvent under reduced
pressure and purification of the residue by flash chromatog-
raphy on SiO2 (cyclohexane–EtOAc, 3:1) afforded the
products (7 or 9) as colorless oils or solids.
In conclusion, a gold(I)-catalyzed method for the synthe-
sis of 4-alkylidene-2-oxazolidinones has been developed
which offers a convenient (and modular) access to a vari-
ety of new oxazolidinone derivatives.14 We are currently
investigating applications of this methodology in the syn-
thesis of pharmacologically relevant compounds.
Acknowledgment
This work was supported by the Volkswagenstiftung and the Japa-
nese Society for the Promotion of Science (JSPS postdoctoral fel-
lowship to Y.H.). The authors would like to thank Dr. Matthias
Schäfer for MS measurements and Dr. Nils Schlörer for assistance
in NMR spectroscopy.
References and Notes
(1) For some leading references, see: (a) Reck, F.; Zhou, F.;
Girardot, M.; Kern, G.; Eyermann, C. J.; Hales, N. J.;
Ramsay, R. R.; Gravestock, M. B. J. Med. Chem. 2005, 48,
499. (b) Barbachyn, M. R.; Ford, C. W. Angew. Chem. Int.
Ed. 2003, 42, 2010; Angew. Chem. 2003, 115, 2056.
(c) Kakeya, H.; Morishita, M.; Koshino, H.; Morita, T.;
Kobayashi, K.; Osada, H. J. Org. Chem. 1999, 64, 1052.
(2) (a) Ager, D. J.; Prakash, I.; Schaad, D. R. Chem. Rev. 1996,
96, 835. (b) Gage, J. R.; Evans, D. A. Org. Synth. 1990, 68,
83; Org. Synth., Coll. Vol. VIII; Wiley: New York, 1993,
339. (c) Evans, D. A.; Johnson, J. S. In Comprehensive
Asymmetric Catalysis, Vol. III; Jacobsen, E. N.; Pfaltz, A.;
Yamamoto, H., Eds.; Springer: Berlin, Heidelberg, 1999,
1177.
4-Methylene-3-(toluene-4-sulfonyl)-1-oxa-3-
azaspiro[4.5]decan-2-one (9a): 1H NMR (300 MHz,
CDCl3): d = 1.34–1.74 (m, 10 H), 2.41 (s, 3 H), 4.39 (d, 2J =
3 Hz, 1 H, C=CH), 5.46 (d, 2J = 3 Hz, 1 H, C=CH), 7.31 (d,
3J = 8.3 Hz, 2 H), 7.89 (d, 3J = 8.3 Hz, 2 H). 13C NMR (75
MHz, CDCl3): d = 21.36 (t), 21.65 (q), 24.28 (t), 36.64 (t),
84.83 (s), 90.14 (t), 127.92 (d), 129.75 (d), 134.31 (s),
144.96 (s), 145.94 (s), 150.26 (s). IR (ATR): 1782 (ss, C=O),
1660 (s, C=C) cm–1. MS (DIP–EI, 70 eV): m/z (%) = 321
[M+], 166 (14), 155 (24), 105 (12), 94 (23), 91 (100), 81 (16),
(3) Shibata, I.; Kato, H.; Kanazawa, N.; Yasuda, M.; Baba, A. J.
Am. Chem. Soc. 2004, 126, 466.
Synlett 2006, No. 19, 3309–3313 © Thieme Stuttgart · New York