Organocatalytic Fischer Indolization Using the 2,2′-Biphenol/ B(OH)3 System.

An organocatalyzed Fischer indolization is established by combining 2,2′-biphenol (10 mol%) and B(OH)3 (30 mol%) as weak, readily available, and easy-to-handle acids. The inclusion of MgSO4 , which efficiently scavenges NH3 (a possible acid catalyst poison), appears to be key to the success of this process. The corresponding indoles are obtained in yields of up to 91% using this method.y [ABSTRACT FROM AUTHOR]