title: Rhodium carbene routes to oxazoles and thiazoles. Catalyst effects in the synthesis of oxazole and thiazole carboxylates, phosphonates, and sulfones.
abstract: Dirhodium tetraacetate catalyzed reaction of alpha-diazo-beta-keto-carboxylates and -phosphonates with arenecarboxamides gives 2-aryloxazole-4-carboxylates and 4-phosphonates by carbene N-H insertion and cyclodehydration. In stark contrast, dirhodium tetrakis(heptafluorobutyramide) catalysis results in a dramatic change of regioselectivity to give oxazole-5-carboxylates and 5-phosphonates. Alpha-diazo-beta-ketosulfones behave similarly and give 5-sulfonyloxazoles upon dirhodium tetrakis(heptafluorobutyramide) catalyzed reaction with carboxamides. The analogous reactions of thiocarboxamides give the corresponding thiazole-5-carboxylates, -phosphonates, and -sulfones.
authors: School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors: Baolu
authors: B
authors: Shi
authors: Alexander J
authors: AJ
authors: Blake
authors: William
authors: W
authors: Lewis
authors: Ian B
authors: IB
authors: Campbell
authors: Brian D
authors: BD
authors: Judkins
authors: Christopher J
authors: CJ
authors: Moody
mesh_terms: D002264:Carboxylic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D063065:Organophosphonates / Q000138:chemical synthesis* / Q000737:chemistry; D010080:Oxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013450:Sulfones / Q000138:chemical synthesis* / Q000737:chemistry; D013844:Thiazoles / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D002264:Carboxylic Acids; D063065:Organophosphonates; D010080:Oxazoles; D013450:Sulfones; D013844:Thiazoles; C030011:carbene; D012238:Rhodium; D008697:Methane