CYCLIC TAUTOMERS OF TRYPTAMINES AND TRYPTOPHANS. V1. FORMATION AND REACTIONS OF CYCLIC TAUTOMERS OF CYCLO-L-TRYPTOPHANYL-L-PROLINE.

Article abstract of DOI:10.1016/S0040-4039(01)90521-0

Two stereoisomeric cyclic tautomers (5 and 6) of cyclo-L-tryptophanyl-L-proline whose stereochemistry was established by x-ray analysis, gave 5- and 6-hydroxytryptophanyl derivatives (10, 11 and 19) on the hydroxylation with lead tetraacetate in trifluoroacetic acid.