Studies Towards the Synthesis of the Core of Endiandric Acid H
In the presence of a CuBr·SMe2 catalytic system, a very simple and efficient approach for the synthesis of the key precursor of the core of endiandric acids starting from the readily and abundantly available 3-butyn-1-ol in five linear steps with an overall yield of 40% was developed.
Synthesis and antifungal activity of novel chiral indole analogues.
Starting from L-tryptophan, 19 new N-substituted chiral indole analogs were synthesized. The prepared compounds were evaluated for biological activity against Sclerotinia sclerotiorum, Alternaria solani, Verticillium dahliae, Colletotrichum orbiculare, Cytospora juglandis and Curvularia lunata. The preliminary bioassays showed that most of the synthesized compounds exhibited fungicidal activity. Compound b13 in particular exhibited significant antifungal activity against Verticillium dahliae and Sclerotinia sclerotiorum, with the MIC value of 1.95 µg mL-1. Compound b13 also showed excellent activity against six plant pathogen fungi, and was identified as the most active on the biological assays, and will be studied further.
Oxidative Coupling via Organocopper Compounds
The type of reaction described here, which achieved preparative importance before the turn of the century in the form of the Glaser reaction, has found new applications in recent years: Syntheses of 1,3-dienes, 2,3,6,7-tetraaza-1,3,5,7-tetraenes, 2,3-diaza-1,3-dienes, hydrazine derivatives, bis(heteroallyl) compounds, hetarenes, polyhetarenes, cyclopolyarenes, protophanes, phanes, and heteraprotophanes. The reaction, which consists in the metalation of the starting substance followed by oxidative coupling of the metal derivative, merits special preparative interest when several successive coupling processes are possible (e. g. polyyne, polyarene, cyclopolyarene, and protophane syntheses). The main factors limiting its applicability are the high thermal stability of some organic copper compounds and the disproportionation of the ligands that frequently occurs as a competing reaction. Selective asymmetric linkages are not generally possible by this method.