Fig. 2: Synthesis of coupling fragments.
From: Enantioselective total synthesis of lycoposerramine congeners through late-stage nitrogen deletion
A Enzymatic hydroxylation of L-pipecolic acid 7, followed by chemical modifications to prepare piperidine fragments 10 − 13. B Cu-catalyzed pyridine ring construction to obtain ( ± )− 16 and its conversion to additional THQ fragments 17 − 20. Yields in brackets refer to overall yield from ( ± )− 16.
