A new pyrrolizidine alkaloid N-oxide and the revised structure of sceleratine

✍ Scribed by Martin W. Bredenkamp; Adriaan Wiechers; Petrus H. van Rooyen

• Publisher: Elsevier Science
• Year: 1985
• Tongue: French
• Weight: 225 KB
• Volume: 26
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)80930-8

✦ Synopsis

Sceleratine [l] and its N-oxide [Z] have been isolated from Senecio ZatifoZius DC and their structures determined by spectroscopic and chemical methods and X-ray crystal= lography. Recently we isolated the N-oxide of merenskine [3],' a new pyrrolizidine alkaloid N-oxide from Senecio Zatifolius DC.' We have subsequently isolated sceleratine [l] and its N-oxide [Z] from the same source. Sceleratine [l] was first isolated in 19413 but its structure was incorrectly assigned.4 We herein present its correct structure. Freshly collected plants of Senecio %atifoZius DC yielded, after extraction and extensive chromatography, sceleratine N-oxide [2], mp 152°C (dec.; from EtOH), [a];' t48.4 tO.5" (c 1.27; MeOH) and analysed for C1aH2,N0s. The IR (KBr) spectrum of [2] suggested an N-oxide (broad band from 2900 to 3500 cm-*) and a diester (1717 and 1747 cm-l) . The electron impact mass spectrum (EIMS) (70 eV: 151°C) of [2] showed peaks at m/e 369 (M-O; 0.06%), 170 (6.3%), 142 (34%), 125 (12%), 120 (5.2%), 119 (12%), 117 (ll%), 99 (13%), 85 (4.5%), 83 (36%), 81 (ll%), 72 (15%), 55 (45%) and 43 (100%) dalton. In the 'H NMR spectrum of [2] (500 MHz;