title: Synthesis of carboxylic amides by ring-opening of oxazolidinones with Grignard reagents.
abstract: Treatment of N-alkyl-oxazolidin-2-ones with Grignard reagents gives tertiary carboxylic amide products. Various substituted oxazolidinones can be used as illustrated with phenyl, benzyl or isopropyl groups on the 4-position, and methyl, benzyl or p-methoxybenzyl groups on the 3-position (the nitrogen atom). A selection of Grignard reagents were successful, including allyl, benzyl, alkyl and phenyl magnesium halides. The organomagnesium species attacks the carbonyl group and promotes ring-opening of the oxazolidinone. The product tertiary amides are useful substrates for stereoselective transformations and were applied to a highly selective enolate alkylation and to a ring-closing metathesis reaction to a six-membered lactam and hence a formal synthesis of the alkaloids (-)-coniine and (+)-stenusine.
authors.affiliation: Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, S3 7HF, UK.
authors.forename: David
authors.initials: D
authors.lastname: Bensa
authors.forename: Iain
authors.initials: I
authors.lastname: Coldham
authors.forename: Pia
authors.initials: P
authors.lastname: Feinäugle
authors.forename: Ravindra B
authors.initials: RB
authors.lastname: Pathak
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Butlin
mesh_terms: D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry; D002264:Carboxylic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D023303:Oxazolidinones / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000577:Amides; D002264:Carboxylic Acids; D009942:Organometallic Compounds; D023303:Oxazolidinones