Synthesis of carboxylic amides by ring-opening of oxazolidinones with Grignard reagents.
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.
Bensa
David
D
Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, S3 7HF, UK.
Coldham
Iain
I
Feinäugle
Pia
P
Pathak
Ravindra B
RB
Butlin
Roger J
RJ
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
D000577:Amides; D002264:Carboxylic Acids; D009942:Organometallic Compounds; D023303:Oxazolidinones