title: Iterative stereospecific reagent-controlled homologation using a functionalized α-chloroalkyllithium: synthesis of cyclic targets related to epibatidine.
abstract: Enantioenriched 1-chloro-2-(1,3-dioxolan-2-yl)ethyllithium was generated by PhLi initiated sulfoxide-ligand exchange and deployed in situ for sequential double stereospecific reagent-controlled homologation (StReCH) of B-(2-chloro-pyrid-5-yl) pinacol boronate. This process afforded highly functionalized contiguous stereodiad motifs (typically, % ee ≥ 98%, dr ≥ 85:15) amenable to subsequent annulative transformations as demonstrated by the concise synthesis (5-7 steps) of cyclic adducts related to the analgesic alkaloid epibatidine.
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, United States.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Emerson
authors.forename: Lev N
authors.initials: LN
authors.lastname: Zakharov
authors.forename: Paul R
authors.initials: PR
authors.lastname: Blakemore