Synthesis of 3-sulfenyl- and 3-selenylindoles by the Pd/Cu-catalyzed coupling of N,N-dialkyl-2-iodoanilines and terminal alkynes, followed by n-Bu(4)NI-induced electrophilic cyclization.
3-Sulfenyl- and 3-selenylindoles are readily synthesized by a two-step process involving the palladium/copper-catalyzed crossing coupling of N,N-dialkyl-ortho-iodoanilines and terminal alkynes and subsequent electrophilic cyclization of the resulting N,N-dialkyl-ortho-(1-alkynyl)anilines with arylsulfenyl chlorides or arylselenyl chlorides. The presence of a stoichiometric amount of n-Bu(4)NI is crucial to the success of the electrophilic cyclization. A variety of 3-sulfenyl- and 3-selenylindole derivatives bearing alkyl, vinylic, aryl, and heteroaryl substituents have been prepared in good to excellent yields (up to 99%). By employing N,N-dibenzyl-ortho-iodoanilines, a 3-sulfenyl-N-H-indole has been successfully prepared. In addition, 3-sulfonyl- and 3-sulfinylindoles have also been successfully prepared by facile oxidation of the corresponding 3-sulfenylindoles.
Chen
Yu
Y
Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Cho
Chul-Hee
CH
Shi
Feng
F
Larock
Richard C
RC
D000480:Alkynes / Q000737:chemistry*; D000814:Aniline Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D007211:Indoles / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*
D000480:Alkynes; D000814:Aniline Compounds; D007211:Indoles; D010165:Palladium; D003300:Copper; D010100:Oxygen