Asymmetric Conjugate Addition of Alkylzirconium Reagents to α,β-Unsaturated Lactones
作者:Eleanor E. Maciver、Rebecca M. Maksymowicz、Nancy Wilkinson、Philippe M. C. Roth、Stephen P. Fletcher
DOI:10.1021/ol501292x
日期:2014.6.20
The asymmetric synthesis of β-substituted lactones by catalytic asymmetric conjugate addition of alkyl groups to α,β-unsaturatedlactones is reported. The method uses alkylzirconium nucleophiles prepared in situ from alkenes and the Schwartz reagent. Enantioselective additions to 6- and 7-membered lactones proceed at rt, tolerate a wide variety of functional groups, and are readily scalable. The method
Enantioselective Copper(I)-Phosphoramidite Catalyzed Addition of Alkylzirconium Species to Acyclic Enones
作者:Philippe M. C. Roth、Stephen P. Fletcher
DOI:10.1021/acs.orglett.5b00021
日期:2015.2.20
asymmetric conjugate addition reactions of alkylzirconium species to acyclic enones are reported. The alkylzirconium nucleophiles are generated in situ by hydrozirconation of alkenes with the Schwartz reagent. The reaction proceeds under mild and convenient conditions. A variety of functionalized nucleophiles can be used, and the method tolerates some variation in enone scope. The method uses a new chiral
According to the present invention, there is provided a catalytic complex comprising a metal, one or more ligands and one or more counterions, wherein said one or more ligands include a non-racemic chiral ligand and wherein said one or more counterions include a triflimide counterion. Also provided are methods of making said catalytic complex and processes for producing chiral compounds which involve the use of said catalytic complex. In addition, the present invention provides compounds of the formula (2) as defined herein. The compounds of formula (2) may be useful as ligands in catalytic complexes.
Asymmetric Conjugate Addition of Alkylzirconocenes to Cyclopent-4-ene-1,3-dione Monoacetals
作者:Stephen Fletcher、Emeline Rideau、Florian Mäsing
DOI:10.1055/s-0034-1379928
日期:——
Copper-catalyzed asymmetric conjugate additions are powerful reactions that allow the formation of single-enantiomer building blocks in a few steps. However, highly enantioselective conjugate addition to five-membered-ring substrates is more challenging and is often neglected. Here, we report catalytic asymmetric 1,4-addition of alkylzirconocenes, formed in situ from readily available alkenes, to cyclopent-4-ene-1,3-dione monoacetals. Good to high enantioselectivities are observed and the procedure tolerates various functional groups.