Hydroxylamine catalyzed Nazarov cyclizations of divinyl ketones
摘要:
The first examples of iminium catalyzed Nazarov cyclizations of divinyl ketones are presented. Experiments describing hydroxylamine catalysis of the cyclization of eight alpha-alkoxy divinyl ketones (60-79% yield) and one unactivated divinyl ketone (38% yield) are reported. Phenyl substitution at the beta-position of the divinyl ketone inhibits cyclization, whereas beta-alkyl substituted beta-alkoxy divinyl ketones readily cyclize. (C) 2015 Elsevier Ltd. All rights reserved.
New Annulations via Platinum-Catalyzed Enyne Cyclization and Cyclopropane Cleavage
作者:Cristina Nevado、Catalina Ferrer、Antonio M. Echavarren
DOI:10.1021/ol0486573
日期:2004.9.1
[reaction: see text] Oxidative ringopening of 3-oxabicyclo[4.1.0]hept-4-enes, formed by the intramolecular Pt(II)-catalyzed cyclopropanation of enol ethers by alkynes, gives oxepane derivatives. Alternatively, the acid-catalyzedopening of the cyclopropane ring leads to dihydrobenzofurans or 3,4-dihydro-2H-chromenes.