Regioselective Synthesis of 3-Indolyl(alkoxy)acetates

The regioselective synthesis of N-carbomethoxy-2-alkoxyindolenines and ?-alkoxyindoles is reported. Bromination of indole 5 with NBS/AIBN/CCl4 gave ?-bromoindole 6 which after treatment with ROH/3Å molecular Sieves afforded (Z-) and (E)-2-alkoxyindolenines 8a-d as the main products, together with minor amounts of ?-alkoxyindoles 9a-d. The reversed regioselectivity was achieved in the absence of molecular Sieves to give ?-alkoxyindoles 9a-d as the main products, while no traces of Z- or E-8a-d were detected.