2.52–2.35 (m, 2H), 2.15–2.03 (m, 2H), 1.26–1.15 (9H). Data are
in agreement with those reported in the literature.8b
Experimental section
General methods
Acknowledgements
All manipulations were carried out under a nitrogen atmosphere
using standard Schlenk techniques. Ethyl diazoacetate and tert-
butyl diazoacetate were purchased and employed without further
purification. The complexes [TpXCu]12,13 and diazocompounds16
were prepared according to literature procedures. Reagents and
solvents were dried and degassed before use. NMR spectra were
recorded on a 400 MHz spectrometer (13C NMR at 100 MHz)
using CDCl3 as the solvent.
We thank the MEC (Proyecto CTQ2008-00042/BQU) and the
Junta de Andaluc´ıa (Proyecto P07-FQM-02794) for financial
support. CM thanks the Universidad de Huelva (Plan Propio de
Investigacio´n) for a research fellowship.
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A solution of the corresponding diazocompound (1 mmol) in
20 mL of CH2Cl2 was added either in one portion or with the
aid of a syringe pump over the desired time to a solution of TpxCu
(0.0125 mmol) in 20 mL of CH2Cl2. After addition, the consump-
tion of the diazocompound (diazoacetates or diazocetamides) was
monitored by IR. When no diazo was observed, volatiles were
removed under vacuum and the reaction crude was analyzed by
1H NMR spectroscopy. All the products have been previously
described and their identification was straightforward from com-
parison with the data reported. Conversions were determined by
1H NMR spectroscopy using 1,4-dimethoxybenzene as an internal
standard. Isolated yields of representative examples were obtained
upon purification of products by column chromatography with
neutral silica gel or basic alumina following previously described
procedures.8b,10,17,18,19
5,5-Dimethyl-dihydrofuran-2-one (5). 1H NMR (400 MHz,
CDCl3) d 2.6 (t, J = 8.3 Hz, 2H), 2.0 (t, J = 8.3, Hz, 2H), 1.4 (s,
1H). Data are in agreement with those reported in the literature.17
4,4-Dimethyloxetan-2-one (6). 1H NMR (400 MHz, CDCl3)
d 3.18 (s, 2H), 1.52 (s, 6H). Data are in agreement with those
reported in the literature.18
5-Methyl-dihydrofuran-2-one (7). 1H NMR (400 MHz,
CDCl3) d 4.6 (tq, J = 7.8, 6.2 Hz, 1H), 2.6–2.5 (m, 2H), 2.5–
2.3 (m, 1H), 1.9–1.7 (m, 1H), 1.4 (d, J = 6.2 Hz, 3H). Data are in
agreement with those reported in the literature.17
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Pe´rez, Dalton Trans., 2006, 5999.
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14 For excellent works on the regioselectivity of this reactions see
references 4c and 7c and: A. Padwa, D. J. Austin, A. T. Price, M. A.
Semones, M. P. Doyle, M. N. Protopopova, W. R. Winchester and A.
Trans, J. Am. Chem. Soc., 1993, 115, 8669–8680.
1-Ethyl-4-methylazetidin-2-one (8). 1H NMR (400 MHz,
CDCl3) d 3.56 (m, 1H), 3.33 (m, J = 2H), 2.95 (m, 1H), 2.88
(dd, J = 14.3, 4.8 Hz, 1H), 2.35 (dd, J = 14.3, 2.1 Hz, 1H), 1.23
(d, J = 6.1 Hz, 3H), 1.1 (t, J = 7.2 Hz, 3H). Data are in agreement
with those reported in the literature.19
1-Ethylpyrrolidin-2-one (9). 1H NMR (400 MHz, CDCl3) d
3.32 (m, 2H), 3.25 (q, J = 7.6 Hz, 2H), 2.31 (t, J = 8.2 Hz, 2H),
1.95 (m, 2H), 1.05 (t, J = 7.4 Hz, 3H). Data are in agreement with
those reported in the literature.10
1-Isopropyl-4,4-dimethylazetidin-2-one
(10). 1H
NMR
15 J. Adams, M.-A. Poupart, L. Grenier, C. Schaller, N. Ouimet and R.
Frenette, Tetrahedron Lett., 1989, 30, 1749.
(400 MHz, CDCl3) d 3.58 (hept, J = 6.4 Hz, 1H), 2.66 (s, 2H),
1.41 (s, 6H), 1.31 (d, J = 6.9 Hz, 6H). Data are in agreement with
those reported in the literature.8b
16 Diazoacetates and diazoacetamides were prepared as described in: T.
Toma, J. Shimokawa and T. Fukuyama, Org. Lett., 2007, 9, 3195.
17 L. Coulombel and E. Dun˜ach, Synth. Commun., 2005, 35, 153–160.
18 J. K. Crandall, W. H. Machleder and S. A. Sojka, J. Org. Chem., 1973,
38, 1149–1154.
1-Isopropyl-5-methylpyrrolidin-2-one
(11). 1H
NMR
(400 MHz, CDCl3) d 4.22–4.10 (m, 1H), 4.09–4.00 (m, 1H),
19 R. R. Rando, J. Am. Chem. Soc., 1970, 92, 6706–6797.
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