The Journal of Organic Chemistry
Article
(dimethylamino)pyridine (105 mg) in 20 mL of anhydrous CH2Cl2
under N2 was cooled to 0 °C, and dicyclohexylcarbodiimide (20 mL,
1.0 M in CH2Cl2, 20 mmol) was added over a period of 1 min. After
the reaction mixture was stirred for 5 min at 0 °C, the ice bath was
removed for 25 min, and the mixture was gravity-filtered. The filtrate
was washed with 2 × 10 mL aqueous 0.5 M HCl and 20 mL of
aqueous 5% NaHCO3. Drying over MgSO4 and removal of solvent
under reduced pressure gave 3.94 g of crude product as a yellow-
orange viscous oil. Recrystallization from 30 mL of 33% EtOAc/
hexane gave 1.77 g (40% yield) product as a beige powder: mp 71−72
°C; 1H NMR (CDCl3, 500 MHz) δ 2.47 (s, 3H), 5.32 (s, 2H), 7.54 (d,
J = 8.7 Hz, 2H), 8.19 (d, J = 8.7 Hz, 2H); 13C NMR (CDCl3, 125
MHz) δ 26.7, 66.3, 124.1, 128.8, 141.4, 147.9, 160.0, 190.9; HRMS
(CI/TOF-Q) m/z [M]+ calcd for C10H9NO5+H 224.0553, found
spectra).
ACKNOWLEDGMENTS
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The Professional Staff Congress of the City University of New
York is acknowledged for financial support. E.M.G. acknowl-
edges support from the donors of the Petroleum Research
Fund of the American Chemical Society Grant No. 54244-UR4,
and the Eugene Lange Foundation. Computational support was
provided by the Extreme Science and Engineering Discovery
Environment (XSEDE), which is supported by National
Science Foundation Grant No. ACI01053575 as well as the
College of Staten Island CUNY High Performance Computing
Facility. Professor Xin Cui and Ms. Olga Lavinda are thanked
for helpful discussions. Dr. E. Fujita of Brookhaven National
Laboratory is thanked for the use of the Bruker Kappa Apex II
diffractometer for X-ray data collection.
Bis(4-nitrobenzyl) 1H-Benzo[b]azepine-2,4-dicarboxylate
(6). A solution of 2-fluoroaniline (260 μL, 2.67 mmol), p-nitrobenzyl
pyruvate (598 mg, 2.68 mmol), and p-toluenesulfonic acid
monohydrate (5 mg) in 12 mL of o-xylene was heated at reflux
under N2 for 1 h in a Dean−Stark apparatus. After being cooled to rt,
the solution was washed with 2 × 15 mL of aqueous 5% NaHCO3
solution and dried over MgSO4. Removal of the solvent under reduced
pressure at a maximum temperature of 45 °C gave 871 mg of crude
product as a dark brown semisolid. This was stirred with 6 mL of a
mixture of 10% EtOAc/33% CH2Cl2/hexane, causing precipitation of
146 mg dark-brown solid, which was dissolved in approximately 1 mL
of CH2Cl2 and passed through a plug of silica gel. After removal of the
CH2Cl2 by evaporation, recrystallization from 12 mL of 60% EtOAc/
hexane gave 69 mg (10% yield) of product as a dark crystalline solid:
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ASSOCIATED CONTENT
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S
* Supporting Information
The Supporting Information is available free of charge on the
Copies of the crystallographic data (excluding structure factors)
for compound 6 can be obtained, free of charge, on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, (fax:
1
X-ray crystal data for compound 6 and discussion, H
NMR spectrum of compound 4, 1H and 13C NMR
spectra with detailed structural assignments for com-
pounds 5 and 6, variable-temperature NMR spectra for
compounds 4 and 6, and detailed computational data for
compounds 2a−d, 4, 6, and 7 (PDF)
AUTHOR INFORMATION
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Corresponding Authors
Notes
The authors declare no competing financial interest.
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J. Org. Chem. 2016, 81, 3313−3320