Ligand effects in the rhodium(II) catalysed reactions of diazoamides and diazoimides

Article abstract of DOI:10.1016/0040-4020(95)01070-X

A range of substituted α-diazoamides 1-8 and diazoimides 9-12 was prepared from the corresponding amines or amides. Rhodium(II) catalysed decomposition of the diazoamides resulted in attack on the aromatic ring to give oxindoles or attack on the alkyl group to give either β-lactams or cycloheptapyrrolones. The chemoselectivity of the rhodium carbenoid intermediate was dependent on the metal ligands, fluorinated carboxamides strongly promoting attack on aromatic rings in preference to other processes. Decomposition of the diazoimides resulted in intramolecular attack on the carbonyl group to give an ylide which could be trapped inter- or intramolecularly. X-Ray crystal structures are reported for the diazo compounds 2 and 4, the indoles 17 and 25, the β-lactam 20, the cycloheptapyrrolones 24 and 28, the dimer 29 and the Pictet Spengler product 39.