Bicyclic-Guanidine-Catalyzed Asymmetric Michael Addition of 3-Substituted Oxindoles to 2-Cyclopentenone

Asymmetric Synthesis of Arboduridine

The first asymmetric total synthesis of the monoterpenoid indole alkaloid arboduridine has been accomplished. The tricyclic A/B/D ring system was constructed by an enantioselective Michael reaction followed by intramolecular nucleophilic addition. Intramolecular α-amination of a ketone forged the piperidine ring, while a Horner-Wadsworth-Emmons (HWE) reaction was used to form the pyrrolidine ring. A reduction cyclization cascade led to formation of the tetrahydrofuran ring.

The chemistry and biology of guanidine natural products

The present review discusses the isolation, structure determination, synthesis, biosynthesis and biological activities of secondary metabolites bearing a guanidine group.

Organocatalytic asymmetric Michael addition of 3-substituted oxindoles to α,β-unsaturated acyl phosphonates for the synthesis of 3,3′-disubstituted oxindoles with chiral squaramides

The first Michael addition of 3-monosubstituted oxindoles to α,β-unsaturated acyl phosphonates is investigated to give 3,3′-disubstituted oxindoles with excellent results.

Catalyst free C–N bond formation by the reaction of amines with diimides: bulky guanidines

Catalyst free direct addition of cyclic secondary amines to various N,N′-bisaryl substituted carbodiimides led to the formation of bulky guanidines. Furthermore, two equivalents of N,N′-bisaryl substituted carbodiimides upon treatment with piperazine led to the formation of bis guanidines.