Rhodium-Catalysed Intermolecular Alkyne Hydroacylation: The Enantioselective Synthesis of α- and β-Substituted Ketones by Kinetic Resolution
作者:Carlos González-Rodríguez、Scott R. Parsons、Amber L. Thompson、Michael C. Willis
DOI:10.1002/chem.201001748
日期:——
Cleared up! Intermolecularalkynehydroacylation represents a new addition to the range of transition‐metal‐catalysed hydroacylation reactions that can be performed in an enantioselective manner. By using a kineticresolution procedure, both racemic α‐ and β‐substituted aldehydes can be converted into the corresponding enantiomerically enriched substituted enone products (see scheme).
A catalytic asymmetric bromocyclization of trisubstituted olefinic amides that uses a C(2)-symmetric mannitol-derived cyclic selenium catalyst and a stoichiometric amount of N-bromophthalimide is reported. The resulting enantioenriched pyrrolidine products, which contain two stereogenic centers, can undergo rearrangement to yield 2,3-disubstituted piperidines with excellent diastereoselectivity and
we report that the [4 + 1] reaction of common dienes and CO cannot work, at least under the catalysis of [Rh(cod)Cl]2. However, using cyclopropyl-capped dienes (also named allylidenecyclopropanes) as substrates, the corresponding [4 + 1] reaction with CO proceeds smoothly in the presence of [Rh(cod)Cl]2. This [4 + 1] reaction, with a broad scope, provides efficient access to five-membered carbocyclic