The first one‐pot tandem Michael addition/enantioselective Conia‐ene cyclization of N‐protected prop‐2‐yn‐1‐amines with 2‐methylene‐3‐oxoalkanoates promoted by chiral iron(III)/silver(I) cooperative catalysts has been developed. Alkyl 4‐methylenepyrrolidine‐3‐acyl‐3‐carboxylates, which can be transformed into β‐proline derivatives, are obtained in high yield with high enantioselectivity.
A General Organocatalyzed Michael–Michael Cascade Reaction Generates Functionalized Cyclohexenes
作者:Patrick G. McGarraugh、Joshua H. Jones、Stacey E. Brenner-Moyer
DOI:10.1021/jo201140a
日期:2011.8.5
to α,β-unsaturatedaldehydes are susceptible to multiple subsequent reaction pathways. We designed cyclic unsaturated β-ketoester substrates that enabled the development of the first diphenyl prolinol silyl ether catalyzed Michael–Michael cascadereaction initiated by a β-dicarbonyl Michael donor to form cyclohexene products. The reaction conditions we developed for this Michael–Michael cascade reaction
Synthèse du «Propylure», phéromone sexuelle de<i>Pectinophora gossypiella</i>S<scp>AUNDERS</scp>
作者:M. Stoll、I. Flament
DOI:10.1002/hlca.19690520724
日期:——
Abstract10‐Propyl‐trans‐trideca‐5, 9‐dien‐1‐yl acetate (propylure), the sex pheromone of the female pink bollworm moth, has been synthesized by an original procedure. The spectroscopic and physiological properties of the material are identical to that of the natural attractant.
Organocatalytic Sequential Michael Reactions: Stereoselective Synthesis of Multifunctionalized Tetrahydroindan Derivatives
Multifunctionalized tetrahydroindan derivatives with four stereocenters were constructed via two sequential Michael reactions between cyclic gamma,delta-unsaturated-beta-ketoester and nitroalkenes initiated with 0.5-2 mol % of cinchona alkaloid based bifunctional organocatalysts and then with 1 equiv of tetramethylguanidine for cyclization. The desired products could be obtained in high yields (up to 99% yield) with excellent enantioselectivities (95-99% ee) as well as diastereoselectivities (up to >99:1 dr) even on a gram scale.
Cationic Vanadium(IV) Complexes as Efficient Catalysts for Nazarov Cyclizations
作者:Irene Walz、Andreas Bertogg、Antonio Togni
DOI:10.1002/ejoc.200700156
日期:2007.6
Vanadium(IV) species generated in situ from V(salen)Cl2 complexes (1) by reaction with 2 equiv. of AgSbF6 are effective catalysts for Nazarovcyclizations. Thus, dialkenyl ketones bearing α-ester groups are efficiently converted to corresponding cyclopentenones in good yields at room temperature, in the presence of 2 mol-% catalyst. Under such conditions full conversion takes place within minutes for