Elektrochemische Oxidation, VII. Synthese und Struktur von 7‐tert‐Butyl‐2‐methylbenzoxazolen

Abstract

Die anodische Oxidation von 15 tert‐butyl‐substituierten Phenolen 1a–o in wasserfreiem Acetonitril oder in Acetonitril/Perchlorsäure führt zu den entsprechenden 7‐tert‐Butyl‐2‐methylbenzoxazolen 3a–o. Der Strukturbeweis wurde durch unabhängige Synthese von 3k und 13C‐NMR‐Spektroskopie sowie durch Röntgenstrukturanalyse von 7‐tert‐Butyl‐2‐methyl‐5‐benzoxazolcarbaldehyd (3i) geführt. Der Einfluß des Elektrolytsystems auf die Produktbildung wird diskutiert.

Synthesis of Isomeric Isoxazolopyridinones

“…Actually, it differs by about 13 ppm. The signals for the 3-methyl groups in both compounds appear roughly at 11 ppm, which is also typical for fused 3-methyl-isoxazoles [17±22] and not for 2-methyl-oxazoles resonating usually at 14 ppm [16,23,24]. Moreover, an oxazolopyridinone structure is de®nitely ruled out by comparison with the corresponding shifts for the above-mentioned reference compounds in the 13 C NMR spectra, suggesting good correlations only between 8, 9 and 3-methyl-isoxazoloquinolones.…”

“…Some authors revealed confusion of previously published fused isoxazoles with the corresponding oxazoles or reported about remaining uncertainties concerning that isomer problem when structure elucidation was based solely on spectroscopic methods [8,16]. Evidence of structure was furnished by alternative syntheses, respectively [8,16].…”

“…Evidence of structure was furnished by alternative syntheses, respectively [8,16]. We investigated 8 and 9 by means of NMR measurements and ®nally compared the chemical shifts in 13 C NMR spectra to those of 2-methyloxazolo-and 3-methyl-isoxazoloquinolones with already con®rmed structures [8].…”

Synthesis and Electrochemical Behavior of Some New Pyridazine Derivatives

“…The accessible potential range depends upon the solvent and the supporting electrolyte that are used. Typical cyclic voltammogram (anodic oxidation followed by cathodic reduction) was performed [18][19][20][21].…”

2-Methyl-1,3-benzoxazol-4-yl diphenylphosphinate

“…For reference structural data, see: Bruno et al (2004). For related benzoxazole structures, see: Dreher et al (1982); Mrozek et al (1999); Qu et al (2008).…”