Electron-Impact Induced and Thermal Decomposition of Dithranol Derivatives, III: Fragmentations of 10-Alkoxy- and 10-Benzyloxydithranol Radical Cations

✍ Scribed by Hsu-Shan Huang; Klaus K. Mayer; Wolfgang Wiegrebe

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 229 KB
• Volume: 328
• Category: Article
• ISSN: 0365-6233
• DOI: 10.1002/ardp.19953280319

✦ Synopsis

Derivatives of dithranol [anthralin; 1,8-dihydroxy-9( 1OH)anthracenone] with substituents at C-10 are of interest in the search for antipsoriatic remedies 'I. While a wealth of compounds with a C-10 carbon bond was tested 3), only little is known about substituted anthralins with side-chains bound by hetero-atoms directly to C-10 -'I. Our studies on 1 0 4kylthio-and 10-arylthio-1,8-dihydroxy-9( 10H)-anthracenones 6* 8, caused us to synthesize i.a. the dithranol ethers 1-3 and their deuterium-labelled analogues l a and 3a-3c.

Under standard electron-impact ionization conditions (70/12 eV). @so-cleavage 9, processes dominate dissociations in the ion source, in the case of 1 -3 giving rise to strong ions at m/z 241 (M -%) and m/z 225 (M -'OR), while in particular molecular ions of 3 additionally decompose to rearrangement ions at d z 240,226, and 92 (Table ).

In the spectra of 1, la, and 2 d z 240 ions arise by loss of H' from m/z 241; m/z 226 ions come directly from the molecular ions by ejecting C H 2 0 (la: CD20, --i, m/z 227) or CH3CH0, respectively, as confirmed for metastable M+' (BE = const. linked scans). a-Cleavage (M -'CH3) and