R. Varala et al. / Tetrahedron Letters 47 (2006) 877–880
879
M.; Adapa, S. R. Chem. Lett. 2004, 33, 1614; (c) Varala,
R.; Ramu, E.; Adapa, S. R. Bull. Chem. Soc. Jpn. 2006, 79,
1; (d) Varala, R.; Alam, M. M.; Adapa, S. R. Synlett 2003,
720; (e) Alam, M. M.; Varala, R.; Adapa, S. R. Tetra-
hedron Lett. 2003, 5115.
O
R
R
+ _
N
OEt
10. Representative procedure. To a solution of TBAOH
(1.0 M solution in water, 0.3 equiv) in DMSO (1 mL)
was added EDA (1 mmol) at room temperature. Then, the
aldehyde component (1.2 mmol) was added over 15 min to
the reaction mixture, which was stirred at room temper-
ature for the specified time (see Table 3). To the reaction
mixture, saturated ammonium chloride solution (5 mL)
was added and the mixture was extracted with ethyl
acetate. The combined organic layers were dried over
anhydrous Na2SO4, concentrated and further purification
by flash column chromatography using ethyl acetate–
hexane (1:3), gave the corresponding b-hydroxy-a-diazo
carbonyl compound. Most of the products are known and
were determined by comparison of their physical data and
spectral data with those reported in the literature. All new
compounds gave satisfactory spectral data in accordance
with their proposed structures.
R
R
N2
R = n-C4H9
Scheme 2. Possible reactive intermediate.
may be developed into a synthetically useful process,
although further work is needed to expand the scope
of the reaction.
Acknowledgements
V.R. thanks the Council of Scientific Industrial
Research (CSIR, India) for financial support.
Spectral data for new compounds:
Ethyl-3-hydroxy-2-diazo-3-(2-nitrophenyl)-propanoate
(entry 2): Yellow oil: 1H NMR (300 MHz, CDCl3):
d = 1.24 (t, J = 7.2 Hz, 3H), 4.22 (q, J = 7.2 Hz, 2H),
6.36 (s, 1H), 7.42–8.01 (m, 4H); Mass (EI): m/z (%) = 237
(MÀN2)+; Anal. Calcd for C11H11N3O5: C, 49.82; H, 4.18;
N, 15.84. Found: C, 49.75; H, 4.09; N, 15.93.
Ethyl-3-hydroxy-2-diazo-3-(4-cyanophenyl)-propanoate
(entry 4): oil: 1H NMR (300 MHz, CDCl3): d = 1.22
(t, J = 7.2 Hz, 3H), 4.25 (q, J = 7.2 Hz, 2H), 5.95
(s, 1H), 7.42–8.10 (m, 4H); Mass (EI): m/z (%) = 217
(MÀN2)+; Anal. Calcd for C12H11N3O3: C, 58.77; H, 4.52;
N, 17.13. Found: C, 58.61; H, 4.58; N, 17.21.
Ethyl-3-hydroxy-2-diazo-3-(4-fluorophenyl)-propanoate
(entry 5): Yellow oil: 1H NMR (300 MHz, CDCl3):
d = 1.27 (t, J = 7.2 Hz, 3H), 4.25 (q, J = 7.2 Hz, 2H),
6.05 (s, 1H), 6.98–7.66 (m, 4H); Mass (EI): m/z (%) = 238
(M+); Anal. Calcd for C11H11FN2O3: C, 55.46; H, 4.65; N,
11.76. Found: C, 55.38; H, 4.71; N, 11.81.
Ethyl-3-hydroxy-2-diazo-3-(4-bromophenyl)-propanoate
(entry 6): Yellow oil: FT IR (neat, cmÀ1): m 3452, 2985,
2102, 1749, 1698, 1371, 1219, 1021, 749; 1H NMR
(300 MHz, CDCl3): d = 1.21 (t, J = 7.2 Hz, 3H), 4.22
(q, J = 7.2 Hz,2H), 4.61 (s, 1H,), 5.82 (s, 1H), 7.22–7.78
(m, 4H). Mass (EI): m/z (%) = 271 (MÀN2)+; Anal. Calcd
for C11H11BrN2O3: C, 44.17; H, 3.71; N, 9.37. Found: C,
44.10; H, 3.55; N, 9.48.
Ethyl-3-hydroxy-2-diazo-3-(4-methoxyphenyl)-propanoate
(entry 8): oil; FT IR (neat, cmÀ1): m 3435, 2981, 2107, 1757,
1696, 1327, 1217, 1168, 748; 1H NMR (300 MHz, CDCl3):
d = 1.32 (t, J = 7.2 Hz, 3H), 3.88 (s, 3H), 4.24
(q, J = 7.2 Hz, 2H), 5.79 (s, 1H), 6.94–6.98 (m, 2H),
7.76–7.79 (m, 2H). Mass (EI): m/z (%) = 250 (M+); Anal.
Calcd for C12H14N2O4: C, 57.59; H, 5.64; N, 11.19.
Found: C, 57.64; H, 5.59; N, 11.07.
Ethyl-3-hydroxy-2-diazo-3-(2,6-dichlorophenyl)-propano-
ate (entry 9): Yellow oil: FT IR (neat, cmÀ1): m 3387, 2978,
2100, 1749, 1697, 1215, 1016, 752; 1H NMR (300 MHz,
CDCl3): d = 1.25 (t, J = 7.2 Hz, 3H), 3.45 (br s, 1H), 4.21
(q, J = 7.2 Hz, 2H), 6.45 (s, 1H), 7.15–7.38 (m, 3H). Mass
(EI): m/z (%) = 261(MÀN2)+; Anal. Calcd for
C11H10Cl2N2O3: C, 45.70; H, 3.49; N, 9.69. Found: C,
45.58; H, 3.54; N, 9.85.
References and notes
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Am. Chem. Soc. 1989, 111, 2353; (b) Arai, S.; Shirai, Y.;
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13000; (d) Ooi, T.; Takeuchi, M.; Kameda, M.; Maruoka,
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metal organo-catalytic processes, see: (e) Hajos, Z. G.;
Parrish, D. R. J. Org. Chem. 1974, 39, 1615; (f) List, B.;
Lerner, R. A., III; Barbas, C. F. J. Am. Chem. Soc. 2000,
122, 2395; (g) Paras, N. A.; MacMillan, D. W. C. J. Am.
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Chem. Soc., Chem Commun. 1990, 1045.
Ethyl-3-hydroxy-2-diazo-3-(3,4,5-trimethoxyphenyl)-pro-
panoate (entry 10): oil: FT IR (neat, cmÀ1): m 3455, 2985,
2946, 2101, 1741, 1698, 1607, 1435, 1372, 1217, 1171, 745;
1H NMR (300 MHz, CDCl3): d = 1.22 (t, J = 7.2 Hz, 3H),
9. (a) Varala, R.; Ramu, E.; Alam, M. M.; Adapa, S. R.
Synlett 2004, 1747; (b) Varala, R.; Ramu, E.; Alam, M.