A Versatile Approach for the Synthesis of 8H-Thieno[2,3-b]indoles and N-[2-(2-N-(R1,R2)-2-Thioxoacetyl)-phenyl]acetamides from 1-Acetyl-1,2-dihydro-3H-indol-3-one (Acetylindoxyl) and Its Derivatives: A Novel Synthesis of Intermediate (1-Acetyl-1H-indol-3-yl)malononitrile/cyanoacetates

We report on two approaches for the synthesis of new 2-amino-3-cyano/alkoxycarbonyl-8H-thieno[2,3-b]indoles and another one for the synthesis of 2-N,N-dialkylamino-3-cyano/aryl-8H-thieno[2,3-b]indoles , based either on acetylindoxyl and (1-acetyl-1H-indol-3-yl)malononitrile/cyanoacetates or 2-bromoacetylindoxyl transformations. A new, simple, rapid, and efficient method for the synthesis of valuable key intermediate malononitrile/cyanoacetates based on acetylindoxyl condensation with malononitrile or cyanoacetates in the presence of triethylamine has been developed. A number of synthetic procedures for the preparation of thioacetamides , 1-acetylthioisatin , and 2,2-disubstituted indoxyls have been elaborated during the synthesis of thieno[2,3-b]indoles. Thioacetamides have been shown as novel agents active against Mycobacterium tuberculosis H37Rv, the cause of tuberculosis, with minimal inhibitory concentration values ranging between 5 and 21 g/mL.