preparing indoles and intermediates therefor by reacting an n - haloaniline with a β - carbonylic hydrocarbon sulfide to form an azasulfonium halide , reacting the azasulfonium halide with a strong base to form a thio - ether indole derivative , and then reducing the thio - ether indole , e . g . with raney nickel , to form the indole compound . when an acetal or ketal of the β - carbonyl hydrocarbon sulfide is used , the azasulfonium salt is treated with a base , and then with an acid to form the thio - ether indole derivative . when an α - ethyl - β - carbonylic hydrocarbon sulfide is used , the resulting azosulfonium salt reacts with strong base to form a thio - ether indolenine derivative , which on reduction with raney nickel or complex metal hydrides yields 3 - substituted indoles . the aniline may be an aminopyridine to form an aza - indole compound in the process . the azasulfonium salts and thio - ether indole or thio - ether indolenine derivatives can be isolated and recovered from their respective reaction mixtures . the thio - ether - indole and thio - ether indolenine derivatives are useful as intermediates to make the indoles without the thio - ether group . the indoles are known compounds having a wide variety of uses , e . g ., in making perfumes , dyes , amino acids , pharmaceuticals , agricultural chemicals and the like .