Ethyl 11a,12-Dihydrobenzo[b]benzo[5,6][1,4]oxazino[2,3-e][1,4]oxazine-5a(6H)-carboxylate

The 11a,12-dihydrobenzo[b]benzo[5,6][1,4]oxazino[2,3-e][1,4]oxazine heterocyclic system has been used in the construction of heteropropellanes, which attracted much attention not only on the possible modification of drugs, but also for novel materials with unusual and important physical properties. In this communication, the reaction of ethyl 2-(hydroxyimino)propanoate 1 with disulfur dichloride and o-aminophenol, which gave ethyl 11a,12-dihydrobenzo[b]benzo[5,6][1,4]oxazino[2,3-e][1,4]oxazine-5a(6H)-carboxylate in moderate yield, was described. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR and IR spectroscopy, mass-spectrometry and X-ray analysis.


Results and Discussion
Continuing the study of ethyl 2-(hydroxyimino)propanoate reactivity, it was treated with S 2 Cl 2 , pyridine in MeCN followed by addition of o-aminophenol.
The structure of oxazinooxazine 1 was confirmed by means of elemental analysis, high resolution mass-spectrometry, 1 H, 13 C NMR and IR spectroscopy, mass-spectrometry and X-ray analysis ( Figure 1)  We checked this possibility and found that ethyl 2-oxopropanoate did not react with S 2 Cl 2 and o-aminophenol. Therefore, the role of ethyl 2-(hydroxyimino)propanoate is crucial for the formation of oxazinooxazine 1, and it is necessary to find another mechanistic explanation for this reaction. So, the mechanism of this transformation is still unclear and requires further investigation.
The structure of oxazinooxazine 1 was confirmed by means of elemental analysis, high resolution mass-spectrometry, 1 H, 13 C NMR and IR spectroscopy, mass-spectrometry and X-ray analysis ( Figure 1 [1,4]oxazine-5a(6H)-carboxylate 1 from ethyl 2-(hydroxyimino)propanoate and disulfur dichloride was developed. The described experimental procedure may serve as an efficient basis for the synthesis of other fused oxazinooxazines. Fused with benzene rings, oxazinooxazines are important heterocyclic scaffold in the construction of heteropropellanes: structurally interesting propeller-like molecules with application in material sciences and medicinal chemistry [7]. Molbank 2020, 2020,  [1,4]oxazine-5a(6H)-carboxylate 1 from ethyl 2-(hydroxyimino)propanoate and disulfur dichloride was developed. The described experimental procedure may serve as an efficient basis for the synthesis of other fused oxazinooxazines. Fused with benzene rings, oxazinooxazines are important heterocyclic scaffold in the construction of heteropropellanes: structurally interesting propeller-like molecules with application in material sciences and medicinal chemistry [7].

General Information
The solvents and reagents were purchased from commercial sources and used as received. Elemental analysis was performed on a 2400 Elemental Analyzer (Perkin Elmer Inc., Waltham, MA, USA). Melting point was determined on a Kofler hot-stage apparatus and is uncorrected. 1 H were taken with a Bruker AM-300 machine (Bruker AXS Handheld Inc., Kennewick, WA, USA) (at frequencies of 300.1) and 13 C NMR spectra were taken with a Bruker DRX-500 machine (Bruker AXS Handheld Inc., Kennewick, WA, USA) (125.8 MHz) in DMSO-d6 solution, with TMS as the standard. J values are given in Hz. MS spectrum (EI, 70 eV) was obtained with a Finnigan MAT INCOS 50 instrument (Hazlet, NJ, USA). IR spectrum was measured with a Bruker "Alpha-T" instrument in KBr pellet. High-resolution MS spectrum was measured on a Bruker micrOTOF II instrument (Bruker Daltonik Gmbh, Bremen, Germany) using electrospray ionization (ESI). The measurement was performed in a positive ion mode (interface capillary voltage: 4500 V) or in a negative ion mode (3200 V); mass range was from m/z 50 to m/z 3000 Da; external or internal calibration was performed with Electrospray Calibrant Solution (Fluka). Syringe injection was used for solutions in acetonitrile, methanol, or water (flow rate 3 L/min -1 ). Nitrogen was applied as a dry gas; interface temperature was set at 180 °C.
Crystal structure determination was performed in the Department of Structural Studies of Zelinsky Institute of Organic Chemistry, Moscow. X-ray diffraction data were collected at 100 K on a Bruker Quest D8 diffractometer (Bruker Corporation, Germany) equipped with a Photon-III area-detector (graphite monochromator, shutterless φ-and ω-scan technique), using Mo Kα-radiation (0.71073 Å). The intensity data were integrated by the SAINT program and were

General Information
The solvents and reagents were purchased from commercial sources and used as received. Elemental analysis was performed on a 2400 Elemental Analyzer (Perkin Elmer Inc., Waltham, MA, USA). Melting point was determined on a Kofler hot-stage apparatus and is uncorrected. 1 H were taken with a Bruker AM-300 machine (Bruker AXS Handheld Inc., Kennewick, WA, USA) (at frequencies of 300.1) and 13 C NMR spectra were taken with a Bruker DRX-500 machine (Bruker AXS Handheld Inc., Kennewick, WA, USA) (125.8 MHz) in DMSO-d 6 solution, with TMS as the standard. J values are given in Hz. MS spectrum (EI, 70 eV) was obtained with a Finnigan MAT INCOS 50 instrument (Hazlet, NJ, USA). IR spectrum was measured with a Bruker "Alpha-T" instrument in KBr pellet. High-resolution MS spectrum was measured on a Bruker micrOTOF II instrument (Bruker Daltonik Gmbh, Bremen, Germany) using electrospray ionization (ESI). The measurement was performed in a positive ion mode (interface capillary voltage: 4500 V) or in a negative ion mode (3200 V); mass range was from m/z 50 to m/z 3000 Da; external or internal calibration was performed with Electrospray Calibrant Solution (Fluka). Syringe injection was used for solutions in acetonitrile, methanol, or water (flow rate 3 L/min -1 ). Nitrogen was applied as a dry gas; interface temperature was set at 180 • C.