Cycloadditions of Nonstabilized2-Azaallyllithiums (2-Azaallyl Anions) and Azomethine Ylides withAlkenes: [3+2] Approaches to Pyrrolidinesand Application to Alkaloid Total Synthesis

• DOI: 10.1055/s-2003-39285
• Publication Date: 2003-05-20T10:34:35Z
• Authors: William H. Pearson; Patrick Stoy
• Keywords: Pyrrolidine; Azomethine ylide

The [3+2] cycloaddition of 2-azaallyl anions with al­kenes represents an attractive strategy for the synthesis substituted pyrrolidines. Although cycloadditions stabilized by aryl and ester groups have been known more than three decades, only recently versions bearing simply hydrogen or alkyl discovered. These nonstabilized are generated low temperature transmetalation (2-azaallyl)stannanes alkyllithiums. resulting 2-azaallyllithiums undergo certain alkenes alkynes in both intra- intermolecular modes to yield pyrrolidine pyrroline cycloadducts. methodology has extended 2-azapentadienyllithiums, heteroatom-substituted 2-azaallyllithiums, polymer-supported 2-azaallyllithiums. Asymmetric anion also investigated. Nonstabilized azomethine ylides may be from via N-alkylation/destannylation N-protonation/destannylation sequence. Together, allows access a broader range pyrrolidines, since these species complimentary reactivity profiles.