In the presence of copper(I) iodide, heteroaromatic β-iodo-α,β-unsaturated carboxylic acid systems opposed to terminal alkyne afford selectively 6-endo-dig cyclization products via a tandem coupling oxacyclization reaction.

An original and convenient domino route to natural nostoclides I and II has been developed using a two‐step sequence consisting of a copper‐catalyzed tandem reaction associated with Suzuki cross‐coupling. The methodology employed for this total synthesis appeared to be an interesting and sufficiently flexible tool to allow the synthesis of numerous analogues of these nostoclides.magnified image

An easy and mild copper(I)‐catalysed lactonisation of readily available (E)‐2,3‐dihalopropenoic acid derivatives regio‐ and stereoselectively leads to rarely described (Z)‐3‐halo‐5‐ylidene‐5H‐furan‐2‐ones. These compounds are subsequently able to undergo classical Pd‐catalysed cross‐coupling reactions, providing 3‐substituted and 3,4‐disubstituted 5‐ylidene‐5H‐furan‐2‐ones (see scheme).

No abstract

2007 Halogenated carboxylic acids and esters P 0260 Selective Synthesis of Dihalo-Substituted Unsaturated Carboxylic Acids and Derivatives. -A new method for the selective formation of trans-dihalogenated alkenoic acids and acid derivatives is developed. -(LANGLE, S.; NGI, S. I.; ANSELMI, E.; ABARBRI, M.; THIBONNET, J.; DUCHENE*, A.; Synthesis 2007, 11, 1724-1728; Lab. Synth. Physicochim. Org. Ther., Fac. Sci. Tours, F-37200 Tours, Fr.; Eng.) -Jannicke 41-055