title: Synthesis of enantiomerically enriched allenes by (-)-sparteine-mediated lithiation of alkynyl carbamates.
abstract: [reaction: see text]. The alpha-deprotonation of alkynyl carbamates 3 with the chiral base (-)-sparteine (4)/n-butyllithium, transmetalation with ClTi(O(i)()Pr)3, and subsequent substitution with an aldehyde results in the formation of enantioenriched 4-hydroxyallenyl carbamates 11. Stereoselection is determined by dynamic resolution of the lithium/(-)-sparteine complexes by selective crystallization.
authors.affiliation: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, D-48149 Münster, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Schultz-Fademrecht
authors.forename: B
authors.initials: B
authors.lastname: Wibbeling
authors.forename: R
authors.initials: R
authors.lastname: Fröhlich
authors.forename: D
authors.initials: D
authors.lastname: Hoppe
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000466:Alkadienes / Q000138:chemical synthesis*; D008094:Lithium / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D013034:Sparteine / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D000466:Alkadienes; D013034:Sparteine; C025947:propadiene; D008094:Lithium