CYCLIZATIONS OF TRYPTOPHANS .2. PROTONATED SPECIES DERIVED FROM L-TRYPTOPHAN METHYL-ESTER AND ITS N-B-ACETYL DERIVATIVE

L-Tryptophan methyl ester has been shown to undergo protonation in the N-b and 3-position in cone. H2SO4. The absolute configuration and sol ution structures of the resulting diastereomers have been assigned and are discussed. An assignment of H-1 and C-13 NMR signals is presented . After two days in H2SO4 the ester underwent sulfonation giving 5- or 6-monosulfonates and later 5,7-, 4,6-, 2,5-, and 2,6- disulfonates. N -b-Acetyl-L-tryptophan methyl ester was studied analogously in cone. H 2SO4 and afforded the derivative diprotonated at the 3-position and th e amide oxygen. However, sulfonation proceeded analogously to L-trypto phan methyl ester.