A variety of prop-2-ynylamides have been carbonylated under oxidative conditions to give oxazolines, oxazolines with chelating groups, and bisoxazolines bearing an (alkoxycarbonyl)methylene chain at the 5 position in good yields. The cyclization-alkoxycarbonylation process was carried out in alcoholic media at 50-70 °C and under 24 bar pressure of 3:1 carbon monoxide/air in the presence of catalytic amounts of 10% Pd/C or PdI2 in conjunction with KI. Cyclization occurred by anti attack of an oxygen function on the palladium-coordinated triple bond, followed by stereospecific alkoxycarbonylation, strictly resulting in E-stereochemistry. The structures of representative oxazolines and bisoxazolines have been determined by X-ray diffraction analysis.
EFFICIENT AND GENERAL SYNTHESIS OF 5-(ALKOXYCARBONYL)METHYLENE-3-OXAZOLINES BY PALLADIUM-CATALYZED OXIDATIVE CARBONYLATION OF PROP-2-YNYLAMIDES
GABRIELE, Bartolo;
2002-01-01
Abstract
A variety of prop-2-ynylamides have been carbonylated under oxidative conditions to give oxazolines, oxazolines with chelating groups, and bisoxazolines bearing an (alkoxycarbonyl)methylene chain at the 5 position in good yields. The cyclization-alkoxycarbonylation process was carried out in alcoholic media at 50-70 °C and under 24 bar pressure of 3:1 carbon monoxide/air in the presence of catalytic amounts of 10% Pd/C or PdI2 in conjunction with KI. Cyclization occurred by anti attack of an oxygen function on the palladium-coordinated triple bond, followed by stereospecific alkoxycarbonylation, strictly resulting in E-stereochemistry. The structures of representative oxazolines and bisoxazolines have been determined by X-ray diffraction analysis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
