Abstract The synthesis of a new, conformationally restrained analog of tryptophan, 1, 2, 3, 4- tetrahydro-2-amino-2-carboxy-cyclopent [b] indole (5) is described. The key step involves the BF 3· Et 2 O Catalyzed intramolecular cyclization of α-diazoketone 2b into the 1, 2, 3, 4- tetrahydro-cyclopent [b] indol-2-one (3).
