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The synthesis of P,N heterobidentate phosphine / palladium complexes has been realized from P‐stereogenic enantiopure ligands. Five, six or seven membered ring complexes have been fully characterized, notably by X‐ray diffraction, allowing the study of the chelation to a "palladium (II) dichloride" unit. The nature of nitrogen coordination site as well as the size of the ring modify the bite‐angle at the solid state. Five, six or seven membered ring P,N heterobidentate phosphine / palladium complexes has been synthesized from P‐stereogenic ligands. X‐ray diffraction allowed the effect study of the nature of nitrogen coordination site as well as the size of the ring on the bite‐angle at the solid state. [ABSTRACT FROM AUTHOR]

Palladium(II) acetate in association with secondary phosphine oxides provides an efficient catalytic system for [2+1] cycloadditions starting from oxanorbornene derivatives and tertiary propargyl esters giving rise to vinylidenecyclopropanes. This reaction is specific to bidentate phosphinito-phosphinous acid ligands generated from secondary phosphine oxides. The [2+1] cycloaddition was found broad in scope with a high tolerance to various functional groups. Moreover, vinylidenecyclopropanes were straightforwardly converted into oxabicyclo[3.2.1]oct-2-ene derivatives through a palladium-catalyzed ring-expansion. Finally, the oxa bridge cleavage of oxatricyclic compounds yields functionalized 7-membered carbocycles. [ABSTRACT FROM AUTHOR]

Whereas the reaction of norbornadiene with terminal alkynes in the presence of a phosphapalladacycle catalyst leads to the formation of hydroalkynation products, the use of phosphinous acid-phosphinito-containing palladium complexes gives rise to formal [2+1] cycloadducts. An experimental and computational approach was employed to study the mechanisms of the palladium-promoted hydroalkynation and [2+1] cycloaddition. On the one hand, experiments highlight the crucial role of acidolysis steps on the catalytic activities. On the other hand, DFT calculations demonstrate the specificity of the phosphinito-phosphinous acid ligands, that is, the non-equivalence of the two phosphorus atoms but the interchangeability of their properties. These results may have important implications for the mechanism of other palladium-catalyzed transformations especially those involving phosphapalladacycles and phosphinous acid-phosphinito-containing palladium complexes. [ABSTRACT FROM AUTHOR]

A new metal-catalyzed addition reaction of 1,3-diketones to ynamides, which provides access to unprecedented alkoxy-substituted enamides, is disclosed herein. A screening of catalytic systems showed that both a phosphapalladacycle and a cationic gold complex were capable of promoting this reaction rapidly and cleanly. The scope investigation revealed that variously substituted terminal ynamides and cyclic 1,3-diones were well tolerated. The use of internal ynamides led to the formation of both E and Z isomers with low to good selectivities. The proposed mechanism suggests that the phosphapalladacycle acts as a p Lewis acid to activate the ynamide. [ABSTRACT FROM AUTHOR]

An efficient palladium-catalyzed [2+1] cycloaddition between ynamides and norbornenes or norbornadienes is reported. Both phosphapalladacycles and palladium/secondary phosphine oxide catalytic systems were found to be competent for the transformation allowing the preparation of aminomethylenecyclopropanes. The reaction showed general applicability to various functionalized bicyclo[2.2.1]hept-2-enes and ynamides. A chiral phosphapalladacycle was tested to carry out this transformation in an enantioselective fashion. [ABSTRACT FROM AUTHOR]

The title compounds are prepared via a two step procedure involving a transesterification between a diol and diethyl phosphite followed by a palladium-catalyzed coupling of the so-obtained cyclic phosphite with vinyl bromide. Theoretical DFT calculations have been performed on phosphonate and phosphite anions models in order to estimate stereoelectronic effects in five-membered and six-membered ring compounds. [Copyright &y& Elsevier]

A correction to the article "Chemodivergent Palladium-Catalyzed Processes: Role of Versatile Ligands" that was published in the previous issue is presented.