ALKENES AS ALKYNE EQUIVALENTS IN RADICAL CASCADES TERMINATED BY FRAGMENTATIONS
申请人:The Florida State University Research Foundation, Inc.
公开号:US20160347778A1
公开(公告)日:2016-12-01
Disclosed are methods for rerouting radical cascade cyclizations by using alkenes as alkyne equivalents. The reaction sequence is initiated by a novel 1,2 stannyl shift which achieves chemo- and regioselectivity in the process. The radical “hopping” leads to the formation of the radical center necessary for the sequence of selective cyclizations and fragmentations to follow. In the last step of the cascade, the elimination of a rationally designed radical leaving group via β-C—C bond scission aromatizes the product without the need for external oxidant. The Bu
3
Sn moiety, which is installed during the reaction sequence, allows further functionalization of the product via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of enynes into extended polycyclic structures of tunable dimensions.
Design of Leaving Groups in Radical CC Fragmentations: Through-Bond 2c-3e Interactions in Self-Terminating Radical Cascades
作者:Sayantan Mondal、Brian Gold、Rana K. Mohamed、Igor V. Alabugin
DOI:10.1002/chem.201402843
日期:2014.7.7
Radicalcascades terminated by β‐scission of exocyclic CC bonds allow for the formation of aromatic products. Whereas β‐scission is common for weaker bonds, achieving this reactivity for carbon–carbon bonds requires careful design of radicalleavinggroups. It has now been found that the energetic penalty for breaking a strong σ‐bond can be compensated by the gain of aromaticity in the product and
Gold(<scp>i</scp>)-catalyzed nucleophilic cyclization of β-monosubstituted <i>o</i>-(alkynyl)styrenes: a combined experimental and computational study
作者:Cintia Virumbrales、Marta Solas、Samuel Suárez-Pantiga、Manuel A. Fernández-Rodríguez、Marta Marín-Luna、Carlos Silva López、Roberto Sanz
DOI:10.1039/c9ob02126d
日期:——
The stereospecific gold(I)-catalyzed nucleophilic cyclization of β-monosubstituted o-(alkynyl)styrenes to produce C-1 functionalized 1H-indenes including challenging substrates and nucleophiles, such as β-(cyclo)alkyl-substituted o-(alkynyl)styrenes and a variety of alcohols as well as selected electron-rich aromatics, is reported. DFT calculations support the stereochemical outcome of the process