acceptable results. According to this approach an efficient formation of Schiff bases was achieved in the presence of TiCl(4). Substances were isolated by reversed phase chromatography; in some cases isomers were additionally separated by chiral chromatography on Chirobiotic T. When tested on human recombinant melanocortin receptors all the tertiaryamides showed some binding affinities; for the highest affinity
The oxadi-π-methane rearrangement of 2,4-cyclohexadienones to bicyclic ketones was found to proceed with high enantioselectivity (92–97% ee) in the presence of catalytic amounts of a chiral Lewisacid (15 examples, 52–80% yield). A notable feature of the transformation is the fact that it proceeds on the singlet hypersurface and that no triplet intermediates are involved. Rapid racemic background reactions
A sequential carbo-formylation cascade has been developed, involving a free-radical carbo-oximation process, followed by the hydrolysis of the oxime ether. For this purpose, we designed a new SEM O-protected sulfonyl oxime, which enable both rapid radical addition and hydrolysis under mild conditions. The resulting aldehyde-esters were then engaged in various nucleophilic cascades, such as Sakurai
An Efficient Butenolide Annulation via α′-Chloroacetoxylation of Enones Using Manganese(III) Acetate and Chloroacetic Acid
作者:Ayhan S. Demir、Hülya Akgün、Cihangir Tanyeli、Tugmac Sayrac、David S. Watt
DOI:10.1055/s-1991-26555
日期:——
The α′ -chloroacetoxylation of α,β-unsaturated ketones using manganese(III) acetate and chloroacetic acid followed by Arbuzov reaction and intramolecular Horner-Emmons olefination provided a convenient synthesis of annulated 2-buten-4-olides.