Stereochemical Issues Related to the Synthesis of 7,10- 10,16,3':3,4]-The condensation of iminoethers like (III) with anthranilic acid proceeds with inversion of the tryptophan stereocenter C-16a. Epimerization of the tryptophan center also occurs by acylation with o-azidobenzoyl chloride. -(MADRIGAL, A.; GRANDE, M.; AVENDANO, C.; Tetrahedron: Asymmetry 9 (1998) 17, 3115-3123; Dep. Quim. Org. Farm.,