%0 Journal Article %A Caballero, Esmeralda %A Avendaño López, María Carmen %A Menéndez, J. Carlos %T Stereochemical issues related to the synthesis and reactivity of pyrazino[20 ,10 -5,1]pyrrolo[2,3-b]indole-1,4-diones %D 1998 %U https://hdl.handle.net/20.500.14352/133371 %X The cyclization of all four diastereoisomers of cyclo-(Trp-Ala) to the corresponding 3,5a,6,10b,11,11ahexahydro-2H-pyrazino[20 ,10 -5,1]pyrrolo[2,3-b]indoles is studied from the stereochemical point of view. Epimerization of the tryptophan stereocenter during the cyclization and during acylation reactions of the N-2 atom of the tetracyclic derivatives is discussed. %~