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An efficient, room temperature procedure for the cross-coupling of a range of terminal alkynes, using standard Sonogashira cross-coupling conditions (Pd/Cu) is presented. At higher reaction temperatures, head-to-tail or head-to-head dimerisation affords 1,3- and 1,4-disubstituted enynes, respectively as minor products.

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Synthesis of a series of 4-alkynyl-pyrones (III) via Sonogashira coupling is shown to proceed most effectively using the Pd-C/PPh 3 catalyst system. The products act as a dienophile in Diels-Alder reactions as exemplified for the conversion of (IIIb) into the adduct (V). 4-Alkenyl-pyrones (VII) are obtained by Suzuki cross-coupling of (I) with alkenyl boronic acids. -(MARRISON, L. R.; DICKINSON, J. M.; AHMED, R.; FAIRLAMB*, I. J. S.; Tetrahedron Lett. 43 (2002) 49, 8853-8857; Dep. Chem. Mater., Manchester Metrop. Univ., Manchester M1 5GD, UK; Eng.) -Roy 13-134

Against A2780 and K562 Cell Lines. -A plethora of alkyl, aryl, alkenyl and alkynyl substituents is introduced at the 4-position of pyrone (I) by Pd-catalyzed C-C bond forming processes. Preliminary screening of the substituted pyrones against human ovarian carcinoma (A2780) and human chronic myelogenous leukemia (K 562) cell lines identifies alkynyl pyrones (V) and (VI) as excellent anticancer agents. Furthermore, the 4-substituted pyrones, e.g. (IIIa), (IIIb), (Vb), (Vc), and (VI), show antimicrobial activities in a range of species. -(MARRISON, L. R.; DICKINSON, J. M.; FAIRLAMB*, I. J. S.; Bioorg. Med. Chem. Lett. 12 (2002) 24, 3509-3513; Dep. Chem. Mater., Manchester Metrop. Univ., Manchester M1 5GD, UK; Eng.) -H. Hoennerscheid 12-126

Additive. -An efficient procedure for the cross coupling of a range of terminal alkynes using standard Sonogashira coupling conditions is described. At higher temperature, head-to-tail or head-to-head dimerization affords 1,3-and 1,4-disubstituted enynes, respectively, as minor products. -(FAIRLAMB*, I. J. S.; BAEUERLEIN, P. S.; MARRISON, L. R.; DICKINSON, J. M.; Chem. Commun. (Cambridge) 2003, 5, 632-633; Dep. Chem., Univ. York, Heslington, York YO10 5DD, UK; Eng.) -M. Paetzel 25-070