Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXX. Insertions- und Additions-Reaktionen an Diphosphamanganacyclopropanen mit aktivierten Alkinen

Metal-;Containing Heterocycles: Preparation, Properties, Reactions, LXXX. — Insertion and Addition Reactions on Diphosphamanganacyclopropanes with Activated Alkynes The thermally and kinetically stable diphosphamanganabicyclooctadienones 3a — e [R2 = tBu: R1 = iPr (a), nPr (b), Ph (c); R2 = Cy: R1 = nPr (d), Ph (e)] are obtained by the reaction of the alkyne (CCO2Me)2 with the diphosphamanganacyclopropanes (OC)4Mn-PR=PR2 (2a — e). Depending on steric factors the formation of 3a — e occurs in two different ways. In a first step the alkyne is inserted into the P — P bond of 2a — e to give the kinetically labile five-membered rings 1a — e. Subsequently another alkyne is added to the PR2 and a CO group of 1a — e to give 3a — e. In an alternative way the alkyne is added first to the PR2 and a CO group of 2a with formation of the diphosphamanganabicyclohexenone 4a. Insertion of a second alkyne into the P — P bond of 4a affords the bicyclooctadienone 3a. Compound 2a, 3c, and 4a have been characterized by X-ray structural analyses.