946523-96-2Relevant academic research and scientific papers
Palladium-Catalyzed Long-Range Deconjugative Isomerization of Highly Substituted α,β-Unsaturated Carbonyl Compounds
Lin, Luqing,Romano, Ciro,Mazet, Clément
supporting information, p. 10344 - 10350 (2016/08/31)
The long-range deconjugative isomerization of a broad range of α,β-unsaturated amides, esters, and ketones by an in situ generated palladium hydride catalyst is described. This redox-economical process is triggered by a hydrometalation event and is thermodynamically driven by the refunctionalization of a primary or a secondary alcohol into an aldehyde or a ketone. Di-, tri-, and tetrasubstituted carbon-carbon double bonds react with similar efficiency; the system is tolerant toward a variety of functional groups, and olefin migration can be sustained over 30 carbon atoms. The refunctionalized products are usually isolated in good to excellent yield. Mechanistic investigations are in support of a chain-walking process consisting of repeated migratory insertions and β-H eliminations. The bidirectionality of the isomerization reaction was established by isotopic labeling experiments using a substrate with a double bond isolated from both terminal functions. The palladium hydride was also found to be directly involved in the product-forming tautomerization step. The ambiphilic character of the in situ generated [Pd-H] was demonstrated using isomeric trisubstituted α,β-unsaturated esters. Finally, the high levels of enantioselectivity obtained in the isomerization of a small set of α-substituted α,β-unsaturated ketones augur well for the successful development of an enantioselective version of this unconventional isomerization.
Organocatalytic Asymmetric Synthesis of Chiral Dioxazinanes and Dioxazepanes with in Situ Generated Nitrones via a Tandem Reaction Pathway Using a Cooperative Cation Binding Catalyst
Liu, Yidong,Ao, Jun,Paladhi, Sushovan,Song, Choong Eui,Yan, Hailong
supporting information, p. 16486 - 16492 (2016/12/27)
Heterocyclic skeletons play major roles in pharmaceuticals and biological processes. Cycloaddition reactions are most suitable synthetic tools to efficiently construct chemically diverse sets of heterocycles with great structural complexity owing to the s
A chiral phosphoric acid catalyst for asymmetric construction of 1,3-dioxanes
Matsumoto, Akira,Asano, Keisuke,Matsubara, Seijiro
supporting information, p. 11693 - 11696 (2015/07/15)
A novel method of enantioselective 1,3-dioxane construction via a hemiacetalization/intramolecular oxy-Michael addition cascade by a chiral phosphoric acid catalyst was developed. The product was successfully transformed into an optically active 1,3-polyo
Enantioselective, organocatalytic oxy-Michael addition to γ/δ-hydroxy-α,β-enones: Boronate-amine complexes as chiral hydroxide synthons
De, Run Li,Murugan, Andiappan,Falck
, p. 46 - 48 (2008/09/20)
An organocatalytic, enantioselective oxy-Michael addition to achiral γ- and δ-hydroxy-α,β-enones was developed. The key transformation is an unprecedented, asymmetric conjugate addition triggered by complexation between an in situ generated boronic acid hemiester and a chiral amine catalyst. Functionally, the intermediate amine-boronate complex acts as a chiral hydroxide surrogate or synthon. The resultant chiral β-hydroxy-ketones are obtained in good to excellent yields and high ee following mild oxidative removal of the cyclic boronate. Natural products (R,12Z,15Z)-2-hydroxy-4-oxohenicosa-12,15-dienyl acetate and (+)-(S)-streptenol A were synthesized to demonstrate the utility of this reaction. Copyright
