Development of a Titanocene-Catalyzed Enyne Cyclization/Isocyanide Insertion Reaction
摘要:
The first early transition metal-catalyzed enyne cyclization reaction is described. The system converts enyne substrates to bicyclic iminocyclopentenes through the use of 10 mol % of Cp(2)Ti(PMe(3))(2) in the presence of a silyl cyanide. Subsequent hydrolysis produces the corresponding bicyclic cyclopentenones in good overall yield. The cyclization reaction is tolerant of polar functional groups such as ethers, amines, and esters and is diastereoselective with certain chiral enyne substrates.
Scope of the Intramolecular Titanocene-Catalyzed Pauson−Khand Type Reaction<sup>1</sup>
作者:Frederick A. Hicks、Natasha M. Kablaoui、Stephen L. Buchwald
DOI:10.1021/ja990682u
日期:1999.6.1
A Pauson−Khandtype conversion of enynes to bicycliccyclopentenones employing the commercially available precatalyst titanocene dicarbonyl is described. This methodology shows excellent functional group tolerance for a group 4 metallocene-catalyzed process. The scope and limitations of this cyclization with respect to 1,6-, 1,7- and 1,8-enynes with a variety of terminal alkyne substituents, chiral