title: Enantioselective carbolithiation of S-alkenyl-N-aryl thiocarbamates: kinetic and thermodynamic control.
abstract: The addition of n-butyllithium to alkenylthiocarbamates in the presence of (-)-sparteine or the (+)-sparteine surrogate leads to asymmetric carbolithiation, and returns enantiomerically enriched thiocarbamate derivatives of secondary thiols. In THF, with the (+)-sparteine surrogate, in situ aryl migration leads to an enantiomerically enriched tertiary thiol derivative. Remarkably, the two pseudoenantiomeric chiral ligands do not always give enantiomeric products, probably as a result of a complex interplay of kinetic and thermodynamic control. In situ IR and NMR studies of a stable, hindered lithiated thiocarbamate demonstrated its chemical and configurational stability over a period of hours at 0 °C.
authors.affiliation: School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. clayden@man.ac.uk.
authors.forename: Daniele
authors.initials: D
authors.lastname: Castagnolo
authors.forename: Leonardo
authors.initials: L
authors.lastname: Degennaro
authors.forename: Renzo
authors.initials: R
authors.lastname: Luisi
authors.forename: Jonathan
authors.initials: J
authors.lastname: Clayden
mesh_terms: D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D013034:Sparteine / Q000737:chemistry; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013816:Thermodynamics; D013859:Thiocarbamates / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D013859:Thiocarbamates; C046771:butyllithium; D013034:Sparteine