77301-61-2Relevant academic research and scientific papers
Asymmetric Nazarov Cyclizations of Unactivated Dienones by Hydrogen-Bond-Donor/Lewis Acid Co–Catalyzed, Enantioselective Proton-Transfer
Metternich, Jan B.,Reiterer, Martin,Jacobsen, Eric N.
, p. 4092 - 4097 (2020/09/01)
We report an enantioselective Nazarov cyclization catalyzed by chiral hydrogen-bond-donors in concert with silyl Lewis acids. The developed transformation provides access to tri-substituted cyclopentenones in high levels of enantioselectivity (up to 95% e.e.) from a variety of simple unactivated dienones. Kinetic and mechanistic studies are consistent with a reversible 4π-electrocyclization C?C bond-forming step followed by rate- and enantio-determining proton-transfer as the mode of catalysis. (Figure presented.).
Mechanism of the Substitution at the Cyclopropane Ring
Huelskaemper, Ludwig,Weyerstahl, Peter
, p. 746 - 756 (2007/10/02)
Starting from 2a the bicyclic chlorolactone 14a is obtained via 3a and 11a.Reaction of 14a with KOtBu gives the lactone 17b which also is formed from 14b.These results can be explained by a mechanism via the intermediate E.Additional evidence is given by the failure of 15a and b to react with KOtBu and by the product distribution of the reaction of deuterated compound 16a.
