Electrophilic aromatic substitution with N-methoxy-N-acylnitrenium ions generated from N-chloro-N-methoxy amides: syntheses of nitrogen heterocyclic compounds bearing a N-methoxy amide group
Stereoselective Synthesis of Quaternary Center Bearing Azetines and Their β-Amino Acid Derivatives
作者:Christopher J. MacNevin、Rhonda L. Moore、Dennis C. Liotta
DOI:10.1021/jo7018202
日期:2008.2.1
We describe here the use of a stable, four-membered azetine heterocycle for the preparation of highly substituted β-amino acid derivatives. Imidazolidinone chiral auxiliaries were found to eliminate a competitive reaction pathway that had been present under previously reported conditions for azetine synthesis. The ephedrine derived imidazolidin-2-one 21 was allowed to react as its chlorotitanium enolate
Phenylacetaldehyde <i>O</i>-Methyloxime: A Volatile Compound Produced by Grapefruit Leaves Infected with the Citrus Canker Pathogen, <i>Xanthomonas axonopodis</i> pv. <i>citri</i>
作者:Aijun Zhang、John S. Hartung
DOI:10.1021/jf050533x
日期:2005.6.1
An aldehyde oxime amethyl ether, phenylacetalclehyde O-methyloxime, was detected using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) in the headspace above grapefruit leaves infected with Xanthomonas axonopodis pv. citri, the causal agent of citrus bacterial canker disease (CBCD). This disease is a major phytosanitary concern, and an eradication campaign against it is currently underway in Florida. Phenylacetalclehyde O-methyloxime has been reported to be produced by other plants and fragrant flowers, but it was not observed in the headspace above uninfected grapefruit leaves, the pathogenic bacterium X. axonopodis pv. citri itself, or grapefruit leaves infected with another closely related bacterial pathogen, X axonopodis pv. citrumelo, which causes citrus bacterial spot, a disease of no phytosanitary significance. It was also not detected from CBCD infected fruits, including orange, lemon, grapefruit, and lime. We conclude that phenylacetalclehyde O-methyloxime may potentially be used to identify CBCD infestations. However, more intensive studies will be required to fully evaluate the potential of phenylacetalclehyde O-methyloxime as a diagnostic compound for CBCD. Using SPME and GC-MS to measure phenylacetaldehyde O-methyloxime may provide an easy and feasible tool to complement current methods used to detect X axonopodis pv. citri in environmental samples.