1072-19-1Relevant articles and documents
Unprecedented Spectroscopic and Computational Evidence for Allenyl and Propargyl Titanocene(IV) Complexes: Electrophilic Quenching of Their Metallotropic Equilibrium
Ruiz-Muelle, Ana Belén,O?a-Burgos, Pascual,Ortu?o, Manuel A.,Oltra, J. Enrique,Rodríguez-García, Ignacio,Fernández, Ignacio
, p. 2427 - 2439 (2016)
The synthesis and structural characterization of allenyl titanocene(IV) [TiClCp2(CH=C=CH2)] 3 and propargyl titanocene(IV) [TiClCp2(CH2-C≡C-(CH2)4CH3)] 9 have been described for the first time. Advanced NMR methods including diffusion NMR methods (diffusion pulsed field gradient stimulated spin echo (PFG-STE) and DOSY) have been applied and established that these organometallics are monomers in THF solution with hydrodynamic radii (from the Stokes-Einstein equation) of 3.5 and 4.1 ? for 3 and 9, respectively. Full 1H, 13C, Δ1H, and Δ13C NMR data are given, and through the analysis of the Ramsey equation, the first electronic insights into these derivatives are provided. In solution, they are involved in their respective metallotropic allenyl-propargyl equilibria that, after quenching experiments with aromatic and aliphatic aldehydes, ketones, and protonating agents, always give the propargyl products P (when carbonyls are employed), or allenyl products A (when a proton source is added) as the major isomers. In all the cases assayed, the ratio of products suggests that the metallotropic equilibrium should be faster than the reactions of 3 and 9 with electrophiles. Indeed, DFT calculations predict lower Gibbs energy barriers for the metallotropic equilibrium, thus confirming dynamic kinetic resolution.
REGIO ET STEREOCHIMIE DE LA REDUCTION DE DERIVES D'ALCOOLS PROPARGYLIQUES CATALYSEE PAR UN COMPLEXE DE PALLADIUM (O)
Colas, Yann,Cazes, Bernard,Gore, Jacques
, p. 845 - 848 (2007/10/02)
Regio and stereoselectivity of the palladium catalyzed reduction of propargylic halides and esters is greatly influenced by the nature of the hydride donor as by the leaving group.Best results in allene formation are observed in the reduction by lithium triethylborohydride of mesylates and phosphates.In the former case, reaction occurs with anti displacement of the sulfonyl group.