Tandem Enamine Michael Additions to 4-(Mesyloxy)cyclopentenones:  Bridged Tricyclic Skeletons via a Net [3 + 2] Construction¹

Progress in the Construction of Cyclooctanoid Systems: New Approaches and Applications to Natural Product Syntheses

“…A tandem intramolecular enamine−Michael addition and intramolecular enamine alkylation was employed by West and co-workers to create an eight-membered ring, Scheme . Thus, cycloheptanone enamine 299 , on reaction with the preformed synthon 300 underwent a series of reactions to furnish the tricyclic dione 301 .…”

Concerted Conjugate Addition of Nucleophiles to Alkenoates. Part I: Mechanism of N-Alkylhydroxylamine Additions

“…and subsequent coupling of the resulting intermediate 2 with an electrophile (Scheme ). The stereochemistry of conjugate additions can be efficiently controlled by the use of Lewis acids or chiral auxiliaries in starting materials, , often producing anti addition products 3a . , Unactivated olefins 1b ( Y = hydrogen and alkyl group) are electron-rich species and rarely accept nucleophiles. One known exception is the reverse-Cope elimination, which is viewed as the intramolecular addition of a hydroxylamine nucleophile to an olefin to produce a syn addition product .…”

Tandem transformations initiated and determined by the Michael reaction

“…A new procedure for the stereoselective preparation of tricyclo[5.3.1.0 2,6 ]undecane-4,11-diones (49a) and tricyclo-[5.4.1.0 2,6 ]dodecane-4,12-diones (49b) is based on the inter-and intramolecular Michael reactions of 1-pyrrolidinocyclohexene (50a) and -cycloheptene (50b), respectively, with the mesylate 51. 25 Organolithium compounds initiate Michael cyclisation of a,b,c,o-unsaturated bisphosphonates 52. 26 Thus the addition of PhLi to a solution of tetraester 52 afforded cyclic bisphosphonate 53, which is a product of the tandem Michael reaction.…”