Addition of 1,3-dicarbonyl compounds to terminal alkynes catalyzed by a cationic cobalt(iii) complex

Abstract

The Nakamura reaction using the complex, [Cp*Co(CH3CN)3][SbF6]2 as the catalyst has been described. Alkynes on reaction with β-ketoesters afford tetrasubstituted benzenes.

Regio- and Stereoselective Intermolecular Oxysulfonylation of Alkynes with 1,3-Diketones to Access (Z)-β-Sulfonated Enethers

“…Finally, this enolate ( VI ) undergoes a base mediated nucleophilic reaction with the β-iodovinylsulfone ( IV ) and furnishes the corresponding product ( 4 ) with Z-geometry via the elimination of iodide. Similarly, carbanion ( V ) undergoes nucleophilic reaction, when R 3 = Ph, with the β-iodovinylsulfone ( IV ) to give intermediate ( VIII ) which involves a subsequent isomerization of formed diene ( IX ) to the alkene ( 4aq – 4at ) either via stepwise or through [1,5] hydride shift (Scheme ).…”

Synthesis of 4-aryl-3,4-dihydrocoumarins and 4-aryl-4H-chromenes via Er(OTf)3-catalyzed cascade reactions of p-quinone methides with 1,3-dicarbonyl compounds

“…20 1,3-Dicarbonyl compounds have been widely used as versatile and highly active building blocks in organic synthesis because of their intrinsic reactivities. 21 Based on these discoveries, we envisioned that the simultaneous synthesis of 4-aryl-3,4-dihydrocoumarin and 4-aryl-4 H -chromene could be realized through the union of p -QMs and different 1,3-dicarbonyl compounds via a Er(OTf) 3 -catalyzed cascade reaction (Scheme 1, eqn (3)).…”