Acyclic quaternary centers from asymmetric conjugate addition of alkylzirconium reagents to linear trisubstituted enones. Issue 1 (15th September 2016)

• Record Type: Journal Article
• Authors: Gao, Zhenbo; Fletcher, Stephen P.
• Is Part Of: Chemical science. Volume 8:Issue 1(2017)
• Page Start: 641
• Page End: 646
• Publication Date: 2016-09-15
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6sc02811j
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Synthetic methods for the selective formation of all carbon quaternary centres in non-cyclic systems are rare. Here we report highly enantioselective Cu-catalytic asymmetric conjugate addition of alkylzirconium species to twelve different acyclic trisubstituted enones. Abstract : Synthetic methods for the selective formation of all carbon quaternary centres in non-cyclic systems are rare. Here we report highly enantioselective Cu-catalytic asymmetric conjugate addition of alkylzirconium species to twelve different acyclic trisubstituted enones. A variety of sp 3 -hybridized nucleophiles generated by in situ hydrozirconation of alkenes with the Schwartz reagent can be introduced, giving linear products bearing quaternary centres with up to 98% ee. The method is tolerant of several important functional groups and 27 total examples are reported. The method uses a new chiral nonracemic phosphoramidite ligand in a complex with copper triflate as the catalyst. This work allows the straightforward stereocontrolled formation of a valuable structural motif using only a catalytic amount of chiral reagent.