关键词:
Cyclization
Substituents
Mixtures
Aromatic compounds
Molecular structure
摘要:
Cyclization of (S,S)-alpha-[(1-phenylethyl)amino]-alpha-(2-iodophenyl)acetonitrile with (COCl)(2) in toluene or chlorobenzene afforded the atropisomeric pyrazinone (aS,S) 6-(2-alpha-iodophenyl)-3,5-dichloro-1-(1-phenylethyl)-2-(1H)-pyrazinone in 57% yield. With smaller ortho substituents (F, Cl, CH3, CF3, OCH3) on the aromatic ring, mixtures of atropisomers were obtained from the cyclization reaction. All of the individual atropisomers prepared were stable at room temperature. All but the o-fluoro-substituted atropisomers were stable at elevated temperatures. This paper describes a stereoselective synthesis of pyrazinones and suggests a mechanism for formation via an interesting transfer of chirality.