Massenspektrometrie heterocyclischer Verbindungen, 2. Mitt.: Das Fragmentierungsverhalten einiger 2-Acylmethylbenzothia-,-selena-und-imid-azole

Product Class 4: Benzimidazoles

“…Another modification of this general approach has allowed the preparation of 1-acetyl-2methyl-1H-benzimidazole (47) in quantitative yield. Conversion of 44 (R 2 = Me) into the silyl derivative 46 is followed by cyclization by treating it for a minute at room temperature with triflic acid (Scheme 27).…”

“…There appears to be no band corresponding to interaction between the azole and fused benzene rings, a characteristic of benzazoles. [36,46,47] It is entirely typical of substituted benzimidazoles for substituents to leave before the stable aromatic system, so the method can be used as a probe in synthesis. [7] Although the UV spectra of benzimidazoles are of limited value in structural studies unless there are conjugated substituents, some use has been made of absorption and fluorescence spectra of 2-(halomethyl)-and 2-(cyanomethyl)benzimidazoles, [43] and 2,2¢-bisbenzimidazoles.…”

Selenium‐sulfur analogs. Mass spectrometric comparison of substituted selenazoles and thiazoles

“…Selenium-Sulfur Analogs 1339 Table 1 Type of Ions l a 194(14) 1 9 4 ( < l ) 2 3 2 ( < 1 ) 2 3 5 ( < l ) 1 9 3 ( < l ) 193(13) 231 ( < 1 ) 170 (12) 176 ( < 1) 176 (14) 212 ( < 1) 240 (6) 198 (24) 246 (12) 234 (7) 220 (17) (11) 43 (79) selenium heterocycles can be predicted by an examination of the corresponding sulfur analog. The analysis of the mass spectrum of the sulfur compound will therefore aid in the selection of a specific ion from the selenium fragmentation pattern for use in monitoring the levels of the compound in biological fluids.…”