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.
Asymmetric Synthesis of Alkylzincs by Rhodium‐Catalyzed Enantioselective Arylative Cyclization of 1,6‐Enynes with Arylzincs
作者:Jiahua Chen、Tamio Hayashi
DOI:10.1002/anie.202008770
日期:2020.10.12
A chiral diene‐rhodium complex was found to catalyze the reaction of 1,6‐enynes with ArZnCl to give high yields of 2‐(alkylidene)cyclopentylmethylzincs with high enantioselectivity (95–99 % ee). The enantioenriched alkylzincs were readily converted in a one‐pot approach into a wide variety of functionalized products by taking advantage of their unique reactivity. The catalytic cylcle involves arylrhodation
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
An Intramolecular Titanium-Catalyzed Asymmetric Pauson−Khand Type Reaction<sup>1</sup>
作者:Frederick A. Hicks、Stephen L. Buchwald
DOI:10.1021/ja990683m
日期:1999.8.1
The development of the first catalytic asymmetric Pauson−Khandtype cyclization of enynes is described. The active catalyst, (S,S)-(EBTHI)Ti(CO)2 (1), is generated in situ from (S,S)-(EBTHI)TiMe2 (2). A variety of 1,6-enynes can be converted to the corresponding cyclopentenones in high yield (70−94%) with excellent ee's (87−96%). Limitations of the catalyst with respect to substrate structure are discussed