Synthesis of indolenines
N-Indolyltriethylborate is a useful reagent for dearomatizing C3-alkylation of 3-substituted indoles with both activated and nonactivated alkyl halides to give C3-quaternary indolenines, pyrroloindolines, furoindoline, and hexahydropyridoindoline under mild reaction conditions.
A. Lin, J. Yang, M. Hashim, Org. Lett., 2013, 15, 1950-1953.
Iodine-mediated intramolecular cyclization of enamines leads to a various 3H-indole derivatives bearing multifunctional groups in good to high yields under transition metal-free reaction conditions.
Z. He, H. Li, Z. Li, J. Org. Chem., 2010, 75, 4296-4299.