Regioselective Ring Expansion of Isatins with in Situ Generated α-Aryldiazomethanes: Direct Access to Viridicatin Alkaloids
A novel efficient one-pot regioselective ring-expansion reaction of isatins with in situ generated α-aryl/heteroaryldiazomethanes for the construction of viridicatin alkaloids has been described under metal-free conditions. The utility of this protocol is further demonstrated in the synthesis of naturally occurring viridicatin, viridicatol, and substituted 3-O-methyl viridicatin and their scale up.