Application of 2-substituted ethyl isothiocyanates and 2-aminothiols in the synthesis of the analogs of indole phytoalexin camalexin

Treatment of (indol-1-yl)magnesium bromide or iodide with 2-bromoethyl isot hiocyanate afforded 1-(4,5-dihydrothiazol-2-yI)indole (6). Analogous reacti on with 2,2-dimethoxyethyl isothiocyanate led to corresponding 1-thiocarbam oylindole derivative (7), which was cyclized to 1-(5-methoxy-4,5-dihydrothi azol-2-yl)indole (8) by treatment with boron trifluoride etherate. New anal ogs of camalexin, namely 4',5'-dihydrocamalexin (12) and benzocamalexin (14 ) were prepared by cyclocondensation reaction of 1-(tert-butoxycarbonyl) in dole-3-carbaldehyde with cysteamine and 2-aminobenzenethiol. Antifungal act ivity of the prepared compounds was studied, using the fungi Alternaria bra ssicae and Alternaria brassicicola.