C−C-Bond Formation by the Palladium-Catalyzed Cycloisomerization/Dimerization of Terminal Allenyl Ketones: Selectivity and Mechanistic Aspects
作者:A. Stephen K. Hashmi、Thorsten L. Ruppert、Thomas Knöfel、Jan W. Bats
DOI:10.1021/jo970837l
日期:1997.10.1
conditions, besides the normal functional group tolerance known for palladium-catalyzed reactions, an interesting selectivity was observed with functional groups that are known to react either in palladium-catalyzed reactions or reactions catalyzed by other transition-metals. Thus aryl halides, terminal alkynes, 1,6-enynes, and alpha-allenic alcohols were tolerated. In the latter example the selective reaction
Treatment of 1-allenyl-1-diethynyl acetates in the presence of a Au or Pt catalyst (5 mol%) in toluene at room temperature, followed by methanolysis, gave 4-methylene-2-cyclopentenones. The new cationic bisoxazoline (box)-Au(III) complex (S,S)-Phbox- or [(R,R)-Bnbox AuCl2]SbF6} accelerated the reaction, providing the products in moderate yield (60-69%).