title: Synthesis of cyclopentenimines from N-allyl ynamides via a tandem aza-Claisen rearrangement-carbocyclization sequence.
abstract: We describe here details of our investigations into Pd-catalyzed and thermal aza-Claisen-carbocyclizations of N-allyl ynamides to prepare a variety of α,β-unsaturated cyclopentenimines. The nature of the ynamide electron-withdrawing group and β-substituent plays critical roles in the success of this tandem cascade. With N-sulfonyl ynamides, the use of palladium catalysis is required, as facile 1,3-sulfonyl shifts dominate under thermal conditions. However, since no analogous 1,3-phosphoryl shift is operational, N-phosphoryl ynamides could be used to prepare similar cyclopentenimines under thermal conditions through zwitter ionic intermediates that undergo N-promoted H-shifts. Alternatively, by employing ynamides bearing tethered carbon nucleophiles, the zwitter ionic intermediates could be intercepted, giving rise rapidly to more complex fused bi- and tricyclic scaffolds.
authors.affiliation: Division of Pharmaceutical Sciences and Department of Chemistry, 777 Highland Avenue, University of Wisconsin, Madison, Wisconsin 53705-2222, United States.
authors.forename: Xiao-Na
authors.initials: XN
authors.lastname: Wang
authors.forename: Gabrielle N
authors.initials: GN
authors.lastname: Winston-McPherson
authors.forename: Mary C
authors.initials: MC
authors.lastname: Walton
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Richard P
authors.initials: RP
authors.lastname: Hsung
authors.forename: Kyle A
authors.initials: KA
authors.lastname: DeKorver
mesh_terms: D000577:Amides / Q000737:chemistry*; D001372:Aza Compounds / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis*; D007097:Imines / Q000138:chemical synthesis*; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000577:Amides; D001372:Aza Compounds; D003517:Cyclopentanes; D007097:Imines; D010165:Palladium