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• 1663-45-2 1,2-bis-(diphenylphosphino)ethane 

Relevant academic research and scientific papers

Catalytic Enantioselective Hetero-dimerization of Acrylates and 1,3-Dienes

1,3-Dienes are ubiquitous and easily synthesized starting materials for organic synthesis, and alkyl acrylates are among the most abundant and cheapest feedstock carbon sources. A practical, highly enantioselective union of these two readily available pre

Synthesis of 1,4-Cyclohexadiene Carboxylates through a Formal [2+4]-Cycloaddition of Propiolates under Cobalt Catalysis

A low-valent cobalt(I) complex, formed from the reduction of CoBr2(dppe) with zinc, acts as catalyst for the efficient [2+4] cycloaddition of β-alkyl, cycloalkyl and aryl substituted propiolates to dienes. This transformation yields synthetical

Structure and properties of ionic fullerene complex Co+(dppe) 2·(C60-)·(C6H 4Cl2)2: Distortion of the ordered fullerene cage of C60- radical anions

New ionic complex {Co+(dppe)2}·(C 60-)·(C6H4Cl 2)2 (1) was obtained by the reduction of a Co(dppe)Br 2 and C60 mixture by TDAE in o-dichlorobenzene followed by precipitation of crystals by hexane. Optical and EPR spectra of 1 indicated the formation of C60- radical anions and diamagnetic Co +(dppe)2 cations. The structure of 1 solved at 100(2) K involves chains of C60- arranged along the lattice a-axis with a center-to-center distance of 10.271 A. The chains are separated by bulky Co+(dppe)2 cations and solvent molecules. All components of 1 are well ordered allowing the distortion of the C 60- radical anion to be analyzed. An elongation of the C60- sphere by 0.0254(2) was found. It is essentially smaller than those in the salts (Cp*2Ni+) ·(C60-)·CS2 and (PPN +)2·(C602-) with greater distortion of the fullerene cage. The calculation of the electronic structure of fullerene by the extended Hueckel method showed slight splitting of the C60 LUMO, due to the distortion, by three levels. Two levels are located 180 and 710 cm-1 higher than the ground level. The averaged 6-6 and 5-6 bonds in C60- with lengths of 1.397(2) and 1.449(2) A are close to those determined for the C60 2- dianions in (PPN+)2·(C 602-), but are slightly longer and shorter, respectively, than the length of these bonds in neutral C60.

α- And β-Functionalized Ketones from 1,3-Dienes and Aldehydes: Control of Regio- And Enantioselectivity in Hydroacylation of 1,3-Dienes

Ketones are among the most widely used intermediates in organic synthesis, and their synthesis from inexpensive feedstocks could be quite impactful. Regio- and enantioselective hydroacylation reactions of dienes provide facile entry into useful ketone-bearing chiral motifs with an additional latent functionality (alkene) suitable for further elaboration. Three classes of dienes, 2- or 4-monosubstituted and 2,4-disubstituted 1,3-dienes, undergo cobalt(I)-catalyzed regio- and enantioselective hydroacylation, giving products with high enantiomeric ratios (er). These reactions are highly dependent on the ligands, and we have identified the most useful ligands and reaction conditions for each class of dienes. 2-Substituted and 2,4-disubstituted dienes predominantly undergo 1,2-addition, whereas 4-substituted terminal dienes give highly enantioselective 4,1- or 4,3-hydroacylation depending on the aldehyde, aliphatic aldehydes giving 4,1-addition and aromatic aldehydes giving 4,3-addition. Included among the substrates are feedstock dienes, isoprene (US$1.4/kg) and myrcene (US$129/kg), and several common aldehydes. We propose an oxidative dimerization mechanism that involves a Co(I)/Co(III) redox cycle that appears to be initiated by a cationic Co(I) intermediate. Studies of reactions using isolated neutral and cationic Co(I) complexes confirm the critical role of the cationic intermediates in these reactions. Enantioselective 1,2-hydroacylation of 2-trimethylsiloxy-1,3-diene reveals a hitherto undisclosed route to chiral siloxy-protected aldols. Finally, facile syntheses of the anti-inflammatory drug (S)-Flobufen (2 steps, 92% yield, >99:1 er) and the food additive (S)-Dihydrotagetone (1 step, 83% yield; 96:4 er) from isoprene illustrate the power of this method for the preparation of commercially relevant compounds.

Catalytic Enantioselective Synthesis of Cyclobutenes from Alkynes and Alkenyl Derivatives

Discovery of enantioselective catalytic reactions for the preparation of chiral compounds from readily available precursors, using scalable and environmentally benign chemistry, can greatly impact their design, synthesis, and eventually manufacture on scale. Functionalized cyclobutanes and cyclobutenes are important structural motifs seen in many bioactive natural products and pharmaceutically relevant small molecules. They are also useful precursors for other classes of organic compounds such as other cycloalkane derivatives, heterocyclic compounds, stereodefined 1,3-dienes, and ligands for catalytic asymmetric synthesis. The simplest approach to make cyclobutenes is through an enantioselective [2 + 2]-cycloaddition between an alkyne and an alkenyl derivative, a reaction which has a long history. Yet known reactions of this class that give acceptable enantioselectivities are of very narrow scope and are strictly limited to activated alkynes and highly reactive alkenes. Here, we disclose a broadly applicable enantioselective [2 + 2]-cycloaddition between wide variety of alkynes and alkenyl derivatives, two of the most abundant classes of organic precursors. The key cycloaddition reaction employs catalysts derived from readily synthesized ligands and an earth-abundant metal, cobalt. Over 50 different cyclobutenes with enantioselectivities in the range of 86-97% ee are documented. With the diverse functional groups present in these compounds, further diastereoselective transformations are easily envisaged for synthesis of highly functionalized cyclobutanes and cyclobutenes. Some of the novel observations made during these studies including a key role of a cationic Co(I)-intermediate, ligand and counterion effects on the reactions, can be expected to have broad implications in homogeneous catalysis beyond the highly valuable synthetic intermediates that are accessible by this route.