868701-07-9Relevant academic research and scientific papers
Bronsted acid-promoted cyclizations of 1-siloxy-1,5-diynes
Sun, Jianwei,Kozmin, Sergey A.
, p. 13512 - 13513 (2005)
We have developed the first HNTf2-promoted 5-endo-dig cyclizations of 1-siloxy-1,5-diynes, which proceed with concomitant formation of C-Hal bonds as a result of halide abstraction from a halocarbon by the intermediate alkenyl cation. This process is enabled by a chemoselective activation of the more electron-rich siloxy alkyne moiety of the diyne cyclization precursor and represents an efficient and highly diastereoselective method for assembly of a range of β-halo enones. Copyright
Br?nsted acid-promoted cyclizations of siloxy alkynes with unactivated arenes, alkenes, and alkynes
Zhang, Liming,Sun, Jianwei,Kozmin, Sergey A.
, p. 11371 - 11380 (2007/10/03)
In this article, we describe the development of a general concept for the development of new carbon-carbon bond-forming processes, which is based on Br?nsted acid-mediated activation of a siloxy alkyne, followed by efficient interception of the resulting highly reactive ketenium ion by unactivated arenes, alkenes or alkynes. We found that trifluoromethane sulfonimide (HNTf2) proved to be a superior promoter of these reactions compared to a range of other Br?nsted acids. This finding could be attributed to a high acidity of HNTf2 in aprotic organic solvents combined with a low nucleophilicity of the NTf2- anion. Depending on the nature of the nucleophile, the carbocyclizations proceeded either via 6-endo-dig or 5-endo-dig manifolds. In the case of 1-siloxy-1,5-diynes, the cyclizations occurred with a concomitant halide abstraction or arylation.
