Distinction between linear and angular 1,2-alkylenedioxy-benzofurazans and -benzofuroxans by mass spectrometry

✍ Scribed by Takakis, Ioannis M.; Tsantali, Georgia G.; Haas, George W.; Giblin, Daryl; Gross, Michael L.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 241 KB
• Volume: 32
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199711)32:10<1133::aid-jms569>3.0.co;2-k

✦ Synopsis

Distinction between Linear and Angular 1,2-Alkylenedioxy-benzofurazans and -benzofuroxans by Mass Spectrometry Benzofurazans (2,1,3-benzoxadiazoles)1a,b and benzofuroxans (2,1,3-benzoxadiazole 1-oxides) are well known for their pharmacological properties.1c Considering that some of these compounds exhibit biological activity while others do not, we recognize the importance of distinguishing between related isomers. We present herein evidence from mass spectrometry that permits di †erentiation between the linear* benzofurazans 1 and the angular* isomers 2 on the basis of a single fragment ion, that of m/z 80. This ion may also serve to distinguish between the linear and the angular benzofuroxan isomeric pairs 3 and 4 respectively.

The synthesis of all the compounds 1È4 was previously reported.2 Low-resolution electron-ionization (EI) mass spectra were recorded at 70 eV with a Hitachi Perkin-Elmer RMU-6L or a VG Tritech TS-250 mass spectrometer. Highresolution EI mass spectra (HREI-MS) and tandem mass spectra (MS/MS) were acquired with a Kratos MS-50 threesector instrument under conditions similar to those described elsewhere.3 The pertinent ions are listed in Table and exact masses are given in Table . Clearly the angular derivatives * The compounds in which the alkylenedioxy heterocyclic ring is fused to the pseudoaromatic ring with an "f-Ï and "e-bondÏ are arbitrarily referred to as linear and angular, respectively.