Herstellung und reaktivität von alkoxy‐1‐azafulvenen

Abstract

Die Titelverbindungen 7‐9 reagieren mit Nucleophilen an der Lactimethergruppe, während bei 6 Umsetzungen in 4‐Stellung, bei der bromierten Verbindung 14 in 4‐ wie auch in 6‐Stellung möglich sind.

Triethyloxonium Tetrafluoroborate/1,2-Dimethoxyethane – a Versatile Substitute for Trimethyloxonium Tetrafluoroborate in O-Methylation Reactions

“…As expected, we obtained the methoxy derivatives 8a/b exclusively (Scheme 2). The products were identified by comparison with authentic samples, which had been prepared by alternative routes [8].…”

“…Purification by flash column chromatography (EtOAc -cyclohexane, 1 : 3) gave 8b (0.35 g, 50 %) as yellow plates; m. p. 111 • C (MeOH) (lit. [8]: 105 • C). The spectroscopic data are in full accordance with those reported in literature [8].…”

Metal Complexes of Functionalized Sulfur‐Containing Ligands. Part XIX

“…From compound 8 and HClO 4 in AcOH, the crystalline perchlorate 15 was obtained, which hydrolyzed immediately upon contact with H 2 O. Analogously, reaction of 8 with methyl fluorosulfonate gave the pyrroloisothiazolium salt 16, the hydrolysis of which (NaHCO 3 ) led to the imino ester 17, which may be regarded as an −azafulvene× [8], and which was also obtained by reacting 8 with diazomethane in nearly quantitative yield. The preferential O-methylation of lactams is usually interpreted as a hint of the weakened double-bond character of the CO group due to resonance [9].…”