1654
Vol. 55, No. 11
166.88, 162.94, 142.89, 62.20, 25.69, 21.02, 14.11; IR (KBr) 1713, 1624,
1288, 1202 cmꢂ1; HR-MS (EI) Calcd for C7H10N2O3 (Mꢃ) 170.0691, Found
170.0692.
General Procedure for 1,3,4-Oxadiazine-6-ones To a stirred solution
of 5jꢀ (1.13 g, 4.0 mmol) in absolute benzene (20 ml) was added a solution
of DCC (1.07 g, 5.2 mmol) in absolute benzene (2 ml) under N2, and the
whole mixture was stirred at rt for 90 min and then filtered. The filtrate and
washings were evaporated to dryness to give a crystalline yellow solid,
which was triturated with absolute ether to give 6j (0.79 g, 2.98 mmol, 75%)
as light yellow needles.
Fig. 4. Synthesis of 6a
Spectral Data of 6j: 1H-NMR (CDCl3, 400 MHz) d: 8.20 (m, 2H), 7.54—
7.30 (m, 8H), 4.01 (s, 2H); 13C-NMR (CDCl3, 100 MHz) d: 161.34, 153.33,
148.11, 132.79, 132.06, 130.62, 129.31, 129.02, 129.00, 128.55, 127.93,
39.52; IR (KBr) 1766, 1578, 1135 cmꢂ1; HR-MS (EI) Calcd for C16H12N2O2
(Mꢃ) 264.0899, Found 264.0931.
must be stored in a freezer filled with nitrogen.
Conclusion
In summary, we presented here a novel synthetic route to
N-acylhydrazones, pyridazinone compounds, and 1,3,4-oxa-
diazin-6-ones from a-amino acid esters.
Spectral Data of 6a: 1H-NMR (CDCl3, 400 MHz) d: 7.37—7.24 (m, 10H),
4.07 (s, 2H), 3.89 (s, 2H); 13C-NMR (CDCl3, 100 MHz) d: 161.40, 157.58,
148.71, 134.16, 132.69, 129.52, 129.28, 128.93, 128.70, 127.86, 127.37,
39.48, 37.60; IR (KBr) 1766, 1606, 1494, 1453, 1419 cmꢂ1; HR-MS (EI)
Calcd for C17H14N2O2 (Mꢃ) 278.1055, Found 278.1066.
Experimental
1H and 13C spectra were recorded on a JEOL JNM-ECX-400 spectrome-
ter. Chemical shifts were expressed in d ppm with tetramethylsilane as an
1
internal reference for H-NMR and the carbon signal of the corresponding
Acknowledgements This study was supported by MEXT HAITEKU
solvent for 13C-NMR. IR spectra were recorded on a JASCO FT/IR-4100.
Mass spectra were recorded on a JEOL JMS-GCmateII. Melting points were
measured on a Yanaco MP-500P micro melting point apparatus and are not
corrected. THF was distilled from benzophenone ketyl just prior to use.
General Procedure for Reduction with L-Selectride® Diazo ester 1a
(204 mg, 1 mmol) was dissolved in THF (9 ml) and stirred at ꢂ68 °C under
nitrogen atmosphere. To this solution was slowly added L-selectride®
(1.0 ml, 1.0 M in THF). The reaction mixture was stirred for 20 min at the
same temperature, diluted with saturated NH4Cl solution and extracted three
times with ethyl acetate. The combined organic phase was washed with
brine, dried over Na2SO4, and concentrated in vacuo. The resulting residue
was purified by silica gel column chromatography (hexane/ethyl acetate:
2/1) to give 2a as pale yellow crystals (172.9 mg, 84%).
2006, 2007.
References
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General Procedure for Reduction with Tributylphosphine Diazo
ester 1a (427 mg, 2.09 mmol) was dissolved in i-Pr2O (2.1 ml) and stirred at
rt under nitrogen atmosphere. To this solution was added tributylphosphine
(1.57 ml, 6.27 mmol). The reaction mixture was stirred for 150 min at the
same temperature, diluted with ethyl acetate (30 ml) and washed with satu-
rated NaHCO3 solution and brine. The organic phase was dried over
Na2SO4, and concentrated in vacuo. The resulting residue was purified by
silica gel column chromatography (hexane/ethyl acetate: 10/1 to 1/1) to give
2a (401.5 mg, 93%) and 2aꢀ (10.1 mg, 2%).
Spectral Data of 2a and 2aꢀ: 2a: mp 49—50 °C; 1H-NMR (CDCl3,
400 MHz) d: 7.32—7.20 (m, 5H), 6.05 (s, 2H), 4.33 (q, Jꢁ7.2 Hz, 2H), 3.90
(s, 2H), 1.37 (t, Jꢁ7.2 Hz, 3H); 13C-NMR (CDCl3, 100 MHz) d: 165.16,
137.98, 134.82, 128.96, 128.00, 126.85, 61.40, 30.39, 14.29; IR (KBr) 3386,
1698, 1559 cmꢂ1; HR-MS (EI) Calcd for C11H14N2O2 (Mꢃ) 206.1055, Found
1
206.1053; 2aꢀ: mp 67—68 °C; H-NMR (CDCl3, 400 MHz) d: 8.17 (s, 2H),
7.29—7.18 (m, 5H), 4.14 (q, Jꢁ7.2 Hz, 2H), 3.70 (s, 2H), 1.22 (t, Jꢁ7.2 Hz,
3H); 13C-NMR (CDCl3, 100 MHz) d: 162.73, 139.23, 130.38, 128.84,
128.13, 126.07, 60.20, 39.48, 13.98; IR (KBr) 3455, 1693, 1676, 1576,
1540, 1211 cmꢂ1; HR-MS (EI) Calcd for C11H14N2O2 (Mꢃ) 206.1055, Found
206.1065.
Spectral Data of 3e: mp 133—134 °C; 1H-NMR (CDCl3, 400 MHz) d:
9.10 (s, 1H), 4.36 (q, Jꢁ7.2 Hz, 2H), 2.93 (t, Jꢁ8.4 Hz, 2H), 2.57 (t,
Jꢁ8.4 Hz, 2H), 1.38 (t, Jꢁ7.2 Hz, 3H); 13C-NMR (CDCl3, 100 MHz) d:
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