title: Lithium Hexamethyldisilazide-Mediated Enolization of Acylated Oxazolidinones: Solvent, Cosolvent, and Isotope Effects on Competing Monomer- and Dimer-Based Pathways.
abstract: Lithium hexamethyldisilazide (LiHMDS)-mediated enolization of (+)-4-benzyl-3-propionyl-2-oxazolidinone in THF-hydrocarbon mixtures shows unusual sensitivity to the choice of hydrocarbon cosolvent (hexane versus toluene) and to isotopic labeling. Four mechanisms corresponding to monosolvated monomers, trisolvated dimers, octasolvated monomers, and octasolvated dimers were identified. Even under conditions in which the LiHMDS monomer was the dominant observable form, dimer-based metalation was significant. The mechanism-dependent isotope and cosolvent effects are discussed in the context of ground-state stabilization and transition-state tunneling.
authors.affiliation: Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University , Ithaca, New York 14853-1301, United States.
authors.forename: Gabriel J
authors.initials: GJ
authors.lastname: Reyes-Rodríguez
authors.affiliation: Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University , Ithaca, New York 14853-1301, United States.
authors.forename: Russell F
authors.initials: RF
authors.lastname: Algera
authors.affiliation: Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University , Ithaca, New York 14853-1301, United States.
authors.forename: David B
authors.identifier: 0000-0001-6065-1655
authors.initials: DB
authors.lastname: Collum
mesh_terms: D000215:Acylation; D005663:Furans / Q000737:chemistry*; D006586:Hexanes / Q000737:chemistry*; D007553:Isotope Labeling; D018020:Lithium Compounds / Q000737:chemistry*; D015394:Molecular Structure; D023303:Oxazolidinones / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D014050:Toluene / Q000737:chemistry*
chemical_list: D005663:Furans; D006586:Hexanes; D018020:Lithium Compounds; D023303:Oxazolidinones; D012821:Silanes; D012997:Solvents; D014050:Toluene; C018674:tetrahydrofuran; C442341:lithium hexamethyldisilazide