Complexes of PdCl2 with phosphoryl- and thiophosphoryl-substituted phosphines as catalysts for the hydrocarboxylation of olefins

The influence of the ligands Ph₂P(CH₂)_mP(X)Ph₂ (L), where m=1, 2 and X=O, S, on the rate and regional selectivity of the hydrocarboxylation of -olefins has been investigated, catalyzed by PdCl₂, in a series of organic solvents. A high regional selectivity of the process (>80%) for products with normal structure has been achieved by using L with m=2, X=O. The influence of the ligand used and of triphenylphosphine on the properties of the catalytic system in the given reaction has been compared.L. Ya. Karpov Scientific-Research Physicochemical Institute, Russian Academy of Sciences, 103064 Moscow. Institute of Chemical Reagents and High-Purity Chemicals, 107258 Moscow. Institute of Physiologically Active Substances, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2003–2007, September, 1992.     

CO2‐Activation for γ‐Butyrolactones and Its Application in the Total Synthesis of (±)‐Heteroplexisolide E

An efficient nickel(0)‐catalyzed highly regio‐ and stereoselective hydrocarboxylation of homopropargylic alcohols with ZnEt₂ in the presence of CO₂ (1 atm, balloon) to synthesize α‐alkylidene‐γ‐butyrolactones is described. The catalyst is highly active and can be applied for the synthesis of (optically active) mono‐ or bicyclic α‐alkylidene‐γ‐butyrolactones with excellent regio‐ and stereoselectivity and good functional group tolerance. The potential of the reaction has been demonstrated in the first synthesis of (±)‐heteroplexisolide E.