Regioselective electrophilic substitutions of fulvenes with ethyl glyoxylate and subsequent Diels–Alder reactions

Highly regioselective electrophilic substitution of fulvenes with ethyl glyoxylate, catalyzed by EtAlCl2 or Yb(OTf)3 was achieved. Subsequent Diels–Alder reaction of the adduct with various dienophiles provides an efficient protocol toward highly functionalized indane and tricyclo[5.2.1.02,6]dec-8-ene systems.