Cyclotrimerization Reactions with First Row Transition Metals
Sprache des Vortragstitels:
21st International Symposium on Organometallic Chemistry Directed Toward Organic Synthesis
Sprache des Tagungstitel:
Transition metal-catalyzed cycloaddition reactions have become particularly successful examples for high versatile and atom-efficient transformations with [2+2+2] cycloaddition reactions as a particular versatile representative. This reaction stands out as a large number of transition metals are capable to mediate or catalyze this reaction.1 The late(r) metals of the first row of the transition metals have been among the first, from which successful examples of catalytic cyclotrimerizations have been reported.2 These metals, especially nickel and cobalt, exhibit interesting and unique catalytic features compared to the heavier congeners. Most recently our studies led to the discovery of a Co(II)-based catalytic process for the synthesis of phosphinines from diynes and phosphaalkynes, featuring a large substrate scope including even tolerance to nitrile groups in the substrates.3 While our interest is focusing on developing new catalysts and exploiting different oxidation states, we are also interested in discovering the catalytic features of other 3d metals like iron and especially manganese. Except for a few (formal) examples, manganese complexes were not known to catalyze cyclotrimerization reactions so far, although the Cp (cyclopentadienyl) and CO complexes share structural similarities to those of cobalt. The presentation will discuss the development and investigation of cobalt, iron and novel manganese catalysts for [2+2+2] cycloadditions, their catalytic features and scope of substrates.