Carboxamides stereoisomers

Structural studies have been described for a large number of lanthanide (Eu, Gd, Tb and Yb) and Y complexes with macrocychc ligands containing three phosphinate and one carboxamide arms [93,111-115]. Among the 32 possible isomers which may exist, one stereoisomer predominates in aqueous solution, as verified by H, and P NMR spectroscopy. Luminescence studies with the... 

S. Ito et al. utilized the aza-Claisen rearrangement of carboxamide enolates for the enantioselective total synthesis of (-)-isoiridomyrmecin, which is a constituent of Actinidia polygama and exhibits unique bioactivity. The rearrangement of the (S,S) stereoisomer was conducted under standard conditions, and the product was isolated as a single [R,R) stereoisomer in 77% yield. 

The full details of a convenient synthesis of muscarine-type compounds (see Vol. 5, p. 265) have now appeared the use of a transition-metal carbonyl to aid the cyclocondensation of aa-dibromo-ketones with MV-dimethyl-carboxamides gives good yields of 3(2i/)-furanones, which can be converted into the appropriate muscarine. In this way 4-methylmuscarine iodide (1), as a mixture of its two stereoisomers, was synthesised in 17% overall yield. 

---