Preparation, Properties, and Reactions of Metal‐Containing Heterocycles, XCII. Steric and Solvent Effects of the Different Reaction Patterns of Activated Alkynes with Diphosphamanganacyclopropanes

Abstract

The product pattern of the reaction of the alkynes ZCECZ (4-11) [Z = C02R: R = Me (4), Et (5), nPr (6), iPr (7), nBu (8), nPent (91, neo-Pent (lo), cyc-Hex (ll)] with the diphosphamanganacyclopropanes ( O C ) 4 M F P w 2 R 2 (1 -3) depends on the polarity of the employed solvent. With the exception of phosphaalkynes these reactions proceed via metallacyclopropanes and metallacyclopentadienes as intermediates. Depending on the kind of the alkyne, the products are metallacycloheptatrienes or metallabicycioheptadienes[15-181, Reductive elimination results in the formation of highly substituted benzene and pyridine derivatives, respectively. It is surprising that analogous cyclocotrimerizations with electron-poor alkynes are possible by introduction of the )=S group which stems from depro-

Intermolecular Insertion Reactions into the P−P Bond of Oligophosphorus Compounds

“…The mechanism of this reaction may be rationalized by a nucleophilic attack of the phosphorus atom at one carbon atom of the triple bond of the alkyne. [54] Thus, the complexes of d-block transition metals Fe, Ru, Os and Mn with ligands with a PÀ P bond proved to be useful for the activation of unsaturated organic substrates and small molecules leading to novel organometallic complexes.…”

“…Three‐membered heterocycles diphosphamanganacyclopropanes 109 react with alkynes at room temperature in n ‐hexane to give the 5‐membered heterocycle diphosphamangana‐bicyclo[3.3.0]octadienones ( 110 ) (Scheme 45). The mechanism of this reaction may be rationalized by a nucleophilic attack of the phosphorus atom at one carbon atom of the triple bond of the alkyne [54] …”