| abstract |
The invention relates to an effective and economical method of producing 2-unsubstituted indoles of the structural formula (IV) in high yield by palladium-catalyzed combination / ring closure of 2-halogen or 2-trimethylsulfonyloxy aniline (I) and acylsilane derivative (II) with subsequent deprotection - silyl-protecting groups. The method of this invention, in particular, is used to obtain indoles containing acid-labile substituents, such as triazole, acetyl, ketal, cyano and carbamate, or indoles having an easily cleavable group in the benzyl position. The advantages of this method are that it does not require the use of triphenylphosphine or tetrabutylammonium chloride, or lithium chloride. When applied to 5-triazolyl-substituted indoles, this method also eliminates the tendency of triazolyl polymerization in the synthesis of indole according to Fisher. |