A new utility of 1,3,3-tri(1H-indol-3-yl)propan-1-one as a precursor for synthesizing of oxoketene gem-dithiol and 1,2-dithiole-3-thione, using eco-friendly lemon juice as a catalyst.

We have synthesized 1,3,3-tri(1H-indol-3-yl)propan-1-one (5) catalyzed by pure citrus lemon juice via direct alkylation reaction of indole (4) with chalcone (3) in an eco-friendly manner. The key synthon, alkylated indole (5) on treatment with carbon disulfide in an alkaline medium afforded the required oxoketene gem-dithiol (6). Treatment of the substrate (6) with some amines afforded pyrimidine derivatives (8) and/or (10). On subjecting oxoketene gem-dithiol (6) to reaction with phosphorus pentasulfide, it afforded 1,2-dithiole-3-thione derivative (11) as a novel synthesized compound. Cycloaddition reactions of 1,2-dithiole-3-thione (11) with quinones, and/or maleic anhydride in different reaction conditions were applied and furnished 2-(1,1,3-tri(1H-indol-3-yl)-3-thioxoprop-an-2-ylidene)-3a,7a-dihydrobenzo[d] [1,3]dithiole-4,7-dione (13); 2-(1,1,3-tri(1H-indol-3-yl)-3-thioxopropan-2-ylidene)dihydro-[1,3]dithiolo[4,5-c]furan-4,6-dione (15); 3-(di (1H-indol-3-yl)methyl)-3-(1H-indole-3-carbonothioyl)-2-thioxo-2,3,3a,7a-tetrahydro- benzo[b]thiophene-4,7-dione (16) and 3-(di(1H-indol-3-yl)methyl)-3-(1H-indole-3-carbono-thioyl)-2-thioxo-2,3,3a,9a-tetrahydronaphtho[2,3-b]thiophene-4,9-dione (18). [ABSTRACT FROM AUTHOR]