Hexafluoroisopropanol (HFIP)-Mediated Intramolecular Cyclization of Allenamides To Access C1-Vinyl Tetrahydro-β-carbolines

The construction of biologically interesting N-heterocycles under metal-free conditions is a constant
goal in industry
and academia. Herein, we have developed an hexafluoroisopropanol (HFIP)-mediated
intramolecular cyclization of allenamides, providing tetrahydro-β-carboline
derivatives embedded with a C1-vinyl functionality. The metal-free
protocol provided tetrahydro-β-carboline derivatives atom-efficiently
under room temperature with a broad substrate scope in good to excellent
yields. The potential impact of the protocol is further highlighted
by synthesizing derivatives of biologically important molecules and
diversified scaffolds via postsynthetic modifications.