Catalytic Dicyanative 5-exo- and 6-endo-Cyclization Triggered by Cyanopalladation of Alkynes
作者:Shigeru Arai、Yuka Koike、Atsushi Nishida
DOI:10.1002/adsc.200900813
日期:2010.3.22
A stereoselective dicyanative 5‐exo‐ and 6‐endo‐cyclization using various enynes has been investigated. The mode of cyclization is critically controlled by the structure of the substrates. For example, N‐allyl derivatives prefer 5‐exo‐cyclization, while methacryloyl amides are transformed to the corresponding lactams with tetra‐substituted carbons at the alpha‐position via 6‐endo‐cyclization. Both
An air‐stable cationic AuI complex featuring a Z‐type ligand (boron atom) as a σ‐acceptor was developed for elucidating the effect of B on catalytic reactions. An enynecyclization in the presence of either [Au→B]+ or [Au]+ showed that [Au→B]+ promotes the reactivity, which enabled the effective construction of not only five‐ and six‐membered rings, but also seven‐membered rings.
On the Mechanism of the Puzzling “Endocyclic” Skeletal Rearrangement of 1,6-Enynes
作者:Noemí Cabello、Eloísa Jiménez-Núñez、Elena Buñuel、Diego J. Cárdenas、Antonio M. Echavarren
DOI:10.1002/ejoc.200700402
日期:2007.9
presence of gold(I) catalysts, whereas increasing electron-withdrawing character of substituents at C-4 leads to five-membered rings. Reactions of these simple enynes in the presence of PtCl4 as catalyst give exclusively exo-double skeletal rearrangements. Enynes substituted at the alkyne also react with AuI catalysts to give exclusively products of exo-double rearrangement. The different mechanisms