598-23-2Relevant articles and documents
Synthesis of the complete carbocyclic skeleton of vinigrol
Gentric, Lionel,Hanna, Issam,Ricard, Louis
, p. 1139 - 1142 (2003)
(Matrix presented) An efficient entry to the fully elaborated skeleton of vinigrol is described. The installation of the desired stereochemistry at C(12) and the construction of the eight-membered ring were achieved in one operation by a remarkably facile anionic oxy-Cope rearrangement of Z-isopropenyl isomer 24.
From the lindlar catalyst to supported ligand-modified palladium nanoparticles: Selectivity patterns and accessibility constraints in the continuous-flow three-phase hydrogenation of acetylenic compounds
Vile, Gianvito,Almora-Barrios, Neyvis,Mitchell, Sharon,Lopez, Nuria,Perez-Ramirez, Javier
, p. 5926 - 5937 (2014/05/20)
Site modification and isolation through selective poisoning comprise an effective strategy to enhance the selectivity of palladium catalysts in the partial hydrogenation of triple bonds in acetylenic compounds. The recent emergence of supported hybrid materials matching the stereo- and chemoselectivity of the classical Lindlar catalyst holds promise to revolutionize palladium-catalyzed hydrogenations, and will benefit from an in-depth understanding of these new materials. In this work, we compare the performance of bare, lead-poisoned, and ligand-modified palladium catalysts in the hydrogenation of diverse alkynes. Catalytic tests, conducted in a continuous-flow three-phase reactor, coupled with theoretical calculations and characterization methods, enable elucidation of the structural origins of the observed selectivity patterns. Distinctions in the catalytic performance are correlated with the relative accessibility of the active site to the organic substrate, and with the adsorption configuration and strength, depending on the ensemble size and surface potentials. This explains the role of the ligand in the colloidally prepared catalysts in promoting superior performance in the hydrogenation of terminal and internal alkynes, and short-chain alkynols. In contrast, the greater accessibility of the active surface of the Pd-Pb alloy and the absence of polar groups are shown to be favorable in the conversion of alkynes containing long aliphatic chains and/or ketone groups. These findings provide detailed insights for the advanced design of supported nanostructured catalysts. Hybrid nanocatalysts: The classical Lindlar and the newly developed NanoSelectTM catalysts are confronted in the semi-hydrogenation of alkynes (see figure). Systematic testing under continuous-flow three-phase conditions, coupled with detailed characterization analyses and molecular simulations, enable the understanding of the structure of the catalysts and the associated activity and selectivity patterns for a wide range of acetylenic compounds.
A general and versatile method for C-C cross-coupling synthesis of conjugated enynes: One-pot sequence starting from carbonyl compounds
Lyapkalo, Ilya M.,Vogel, Michael A. K.
, p. 4019 - 4023 (2007/10/03)
(Chemical Equation Presented) Ultimate coupling partners: Widely available enolizable aldehydes and ketones undergo Sonogashira cross-coupling with other carbonyl compounds to give conjugated enynes in a newly devised general method (see scheme; NfF = nonafluorobutane-1-sulfonyl fluoride). The synthetic protocol comprises at least four operating steps, which are carried out in one pot using common reagents, catalysts, and additives.
