Asymmetric synthesis of (S)-tylophorine and (S)-cryptopleurine via one-pot Curtius rearrangement and Friedel–Crafts reaction tandem sequence†
Abstract
A general and practical enantioselective synthetic approach to both the phenanthroindolizidine and phenanthroquinolizidine alkaloids (S)-tylophorine and (S)-cryptopleurine was developed, which features a stereoselective alkylation and a one-pot Curtius reaction rearrangement/intramolecular cyclization cascade sequence.