Gold(I) catalysed cycloisomerisation of β-hydroxy propargylic esters to dihydropyrans/2H-pyrans via allene intermediates
作者:Ramesh Kotikalapudi、K.C. Kumara Swamy
DOI:10.1016/j.tet.2013.07.003
日期:2013.9
Efficient cycloisomerisation of β-hydroxy propargylic esters to dihydropyrans/2H-pyrans via 1,3-carboxylate migration followed by regioselective hydroxyl addition to the transient allene intermediate catalysed by Ph3PAuCl/AgSbF6 is presented. Similar reactions on phosphorylated precursors led to phosphono-furans and phosphono-pyrans. In a few cases, self-condensation of β-hydroxy propargylic esters
A heterogeneous palladium-catalyzed oxidative cyclization of enallenols has been developed for the construction of highly substituted furan and oxaborole derivatives. The heterogeneous catalyst (Pd-AmP-MCF) exhibits high activity, high site- and stereoselectivity, and efficient palladium recyclability in the transformations.
AbstractHerein, we report an electrochemical oxidative palladium‐catalyzed carbonylation‐carbocyclization of enallenols to afford γ‐lactones and spirolactones, which proceeds with excellent chemoselectivity. Interestingly, electrocatalysis was found to have an accelerating effect on the rate of the tandem process, leading to a more efficient reaction than that under chemical redox conditions.