Indole derivatives industrial synthesis

Professor Richard C. Larock reported the Larock indole synthesis in 1991. Since then, the reaction has been studied by both his group and other researchers. The reaction is versatile and practical for the construction of indole ring in a single operation. The reaction has been widely employed for the preparation of indole derivatives in both industrial (on a multikilogram scale) and academic settings. The broad range of products synthesized... 

Since acylated heteroaromatics are active intermediates for the synthesis of various pharmaceuticals, catalytic acylation of heteroaromatics using safe and reusable catalysts is important in pharmaceutical industry. It is found that gallium triflate can act as an efficient catalyst for Friedel-Crafts acylation of furan, pyrrole, and indole derivatives (eq 3-5). Friedel-Crafts acylation of acyl anilides using AICI3 requires a stoichiometric amount of the catalyst and the yields are low. Studies showed that catalytic acylation of aniline derivatives can be achieved in high yields using Ga(OTf)3 (10 mol%) in the presence of LiClOa (eq 6). ... 

The first industrial technology for the synthesis of indole via 4,5,6,7-tetrahydro-indole has been worked out on the basis of the reaction of large-scale cyclohexanone with acetylene (Scheme 1.4) [135-137]. The technology also enables preparation of N-vinyl derivatives of 4,5,6,7-tetrahydroindole and indole. 

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