Platinum-Catalyzed Cycloisomerization Reactions of Enynes

• Published in: Journal of the American Chemical Society Vol. 123; no. 48; pp. 11863 - 11869
• Main Authors: Fürstner, Alois, Stelzer, Frank, Szillat, Hauke
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 05.12.2001; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Physical Sciences; Science & Technology; UNACTIVATED ALKYNES; SKELETAL REORGANIZATION; METACYCLOPRODIGIOSIN; INTERCEPTION; ENOLATE COMPLEXES; SYSTEMS; 1-VINYLCYCLOALKENES; BOND; METATHESIS; ALLYLSILYLATION
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0109343

PtCl2 constitutes an efficient and practical catalyst for a set of different atom economical rearrangement reactions of enynes. This includes (i) a formal enyne metathesis reaction delivering 1,3-dienes, (ii) the formation of polycyclic vinylcyclopropane derivatives, and (iii) an unprecedented O→C allyl shift reaction if unsaturated ethers are employed. Although these transformations produce significantly different structural motifs, they share a common mechanism comprising a cationic manifold triggered by the π-complexation of Pt(II) onto the alkyne unit of the substrates. Strong experimental support for the proposed mechanism comes from deuterium-labeling studies, a careful analysis of the product distribution pattern, and the fact that in some cases PtCl2 can be replaced by simple Lewis or Brønsted acids as the catalysts.