Propargylamine (secondary) as a building block in indole synthesis involving ultrasound assisted Pd/Cu-catalyzed coupling-cyclization method: unexpected formation of (pyrazole)imine derivatives
Publication date: Available online 13 November 2018
Source: Tetrahedron Letters
Author(s): Gangireddy Sujeevan Reddy, Suresh Babu Nallapati, P.S.V.K. Sri Saranya, B. Sridhar, Varadaraj Bhat Giliyaru, Raghu Chandrashekhar Hariharapura, G. Gautham Shenoy, Manojit Pal
Propargylamine (secondary) has been explored as a building block in synthesizing indoles via an ultrasound assisted Pd/Cu-catalyzed coupling-cyclization method. Indoles containing a pyrazole moiety at C-2 attached via the -CH2NH- linker (designed as potential anti-tubercular agents) were synthesized first and then generality / scope of the methodology was expanded by synthesizing other indoles. Unexpected formation of imine side products in first cases helped in synthesizing related (pyrazole)imines via a Cu catalyzed ultrasound assisted aerobic oxidation of precursor amines.