Collect. Czech. Chem. Commun. 1999, 64, 1448-1456

Application of 2-Substituted Ethyl Isothiocyanates and 2-Aminothiols in the Synthesis of the Analogs of Indole Phytoalexin Camalexin

Milan Dzurillaa,*, Martin Ružinskýa, Peter Kutschya, Jalpa P. Tewarib and Vladimír Kováčikc

a Department of Organic Chemistry, Faculty of Natural Sciences, P. J. Šafárik University, Moyzesova 11, SK-041 67 Košice, Slovak Republic
b Department of Agricultural, Food and Nutrition Science, Faculty of Agriculture, Forestry and Home Economics, University of Alberta, Edmonton, T6G2P5 Canada
c Institute of Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, SK-842 38 Bratislava, Slovak Republic


Treatment of (indol-1-yl)magnesium bromide or iodide with 2-bromoethyl isothiocyanate afforded 1-(4,5-dihydrothiazol-2-yl)indole (6). Analogous reaction with 2,2-dimethoxyethyl isothiocyanate led to corresponding 1-thiocarbamoylindole derivative (7), which was cyclized to 1-(5-methoxy-4,5-dihydrothiazol-2-yl)indole (8) by treatment with boron trifluoride etherate. New analogs of camalexin, namely 4',5'-dihydrocamalexin (12) and benzocamalexin (14) were prepared by cyclocondensation reaction of 1-(tert-butoxycarbonyl)indole-3-carbaldehyde with cysteamine and 2-aminobenzenethiol. Antifungal activity of the prepared compounds was studied, using the fungi Alternaria brassicae and Alternaria brassicicola.

Keywords: Indoles; Phytoalexins; Dihydrocamalexin; Benzocamalexin; Antifungal activity.