β-Olefination of 2-Alkynoates Leading to Trisubstituted 1,3-Dienes
摘要:
A phosphine-mediated olefination of 2-alkynoates with aldehydes forming 1,3-dienes with high E-selectivity and up to 88% yield is described. Reaction conditions are optimized and reactions are demonstrated for,various aryl, alkyl, and alkenyl aldehydes and for ethyl 2-alkynoates with different substituents in the delta-position. Proof of concept is shown for the generation of a beta,gamma-unsaturated lactone by intramolecular olefination, and furthermore the use of the generated 1,3-dienes in the Diels-Alder reaction has been demonstrated.
Examination of the olefin–olefin ring closing metathesis to prepare Latrunculin B
作者:Jin She、John W. Lampe、Alexandra B. Polianski、Paul S. Watson
DOI:10.1016/j.tetlet.2008.10.144
日期:2009.1
Three subunits of the potent actin polymerization inhibitor Latrunculin B were synthesized and assembled using olefin-olefin ring closing metathesis chemistry to close the 14-membered macrocycle, Metathesis reactions of substrates with various remote protecting group patterns were examined and gave 6,7-E-lactones as the preferred products. (C 2008 Elsevier Ltd. All rights reserved.
Catalytic Dicyanative [4 + 2] Cycloaddition Triggered by Cyanopalladation Using Ene−Enynes and Cyclic Enynes with Methyl Acrylate
Palladium-catalyzed dicyanative [4 + 2] cycloaddition using various ene−enynes was investigated. The key species in this process is a cyanoallene intermediate that is obtained by the cyanopalladation of conjugated enynes followed by 5-exo-cyclization. To achieve an efficient [4 + 2] cycloaddition reaction, both the smooth generation of this species and critical control of regioselectivity in the 6-endo-cyclization
β-Olefination of 2-Alkynoates Leading to Trisubstituted 1,3-Dienes
作者:Mathias J. Jacobsen、Erik Daa Funder、Jacob R. Cramer、Kurt V. Gothelf
DOI:10.1021/ol2011677
日期:2011.7.1
A phosphine-mediated olefination of 2-alkynoates with aldehydes forming 1,3-dienes with high E-selectivity and up to 88% yield is described. Reaction conditions are optimized and reactions are demonstrated for,various aryl, alkyl, and alkenyl aldehydes and for ethyl 2-alkynoates with different substituents in the delta-position. Proof of concept is shown for the generation of a beta,gamma-unsaturated lactone by intramolecular olefination, and furthermore the use of the generated 1,3-dienes in the Diels-Alder reaction has been demonstrated.