Synthesis of 2-aryl-1,2-dihydronaphtho[1,2-f][1,4]oxazepin-3(4H)- ones. Part I

Oxazepines, which were synthesized in literature by means a variety of methods, are of great importance in heterocyclic chemistry along with biology and pharmacology. In this work we tried to synthesize naphthoxazepines by using a number of Schiff bases, which were synthesized from 2-hydroxy-1-napthaldehyde and anilines. The obtained imines were reduced to amines, acylated with chloroacetyl chloride and cyclised to give naphthoxazepinones in an overall yield of 20-49%. The identifications of the isolated and purified compounds were determined by IR, UV, 1 H-NMR, 13 C-NMR, mass spectra and elemental analysis.


Experimental Section
General.All melting points were taken in open capillaries and uncorrected.IR spectra in KBr were recorded on Mattson 1000 FTR spectrometer and JASCO ST / IR-420 machine and UV spectra were recorded on Unicam UV2-100/Visible spectrometer and 150-20 Hitachi spectrometer. 1 H-NMR and 13 C-NMR spectra were determined at Bruker AC 200L and Bruker 400 MHz spectrometer using CDCl 3 .Mass spectra were obtained in a (LS/MS-APCl) Agilent 1100 MSD Instrument.Elemental analyses were obtained LECO CHNS 932 Machine.Merck Kieselgel HF 254 type-60 and Kieselgel 40-60 µm type were used for TLC.For analytical work 0.25 mm, for preparative work 0.75 mm plates were used.All solvents and reagents used were analytical reagent grade.

Synthesis of Schiff bases 3a-c
Schiff bases 3a-c were synthesized according to the method of Sawich and his coworkers. 26The structures of the Schiff bases 3a-c substrates prepared were determined by IR, UV, 1 H-NMR, 13 C-NMR and mass spectra and compared with literature data.

Reductions of Schiff bases with NaBH 4
Schiff base 3a-c (4mmol) were dissolved in methanol-dioxane (1:1) (20 ml) and then 0.76 g (20 mmol) NaBH 4 was added slowly until the evolution of H 2 gase ceases and yellow color disappears.Ice water was added to the reaction mixture.Crude product was crystallized after preparative TLC (SiO 2 /toluene) purification.

Reactions of reduced Schiff bases 4a-c with chloroacetyl chloride
Chloroacetyl chloride (1.58 ml, 0.02 mole) was added to a vigorously stirred solution of 4a-c (0.01 mole) in dry benzene (50 ml).The reaction mixture was refluxed for 2 hours.The solvent was removed in vacuo and the gummy residue was crystallized from dry ethyl alcohol yielding white crystals 6a-c.

Ring closure reactions of of diacetyl derivatives 6a-c
Compound 6a-c (0.001 mole) was added to 5% NaOH solution (15 ml) and the mixture was stirred on water bath for 1 hour.The white solid obtained on cooling was filtered, washed with water and crystallized from alcohol to give the compounds 7a-c.