Synthesis of naturally occurring uridine-alpha-amino acid derivatives by the application of Ugi reaction.

A simultaneous condensation (Ugi reaction) of four components (aldehyde, amine, isocyanide, and carboxylic acid) may be a useful reaction for the construction of N,N'-disubstituted alpha-aminocarboxamide structure. We have found that the reaction involving (2-picolyl 1-oxide) amine (op-amine) gave rise to a product, one of whose nitrogen-substituent could be easily removed to give mono-substituted derivative. Thus, the polyoxin skeleton as well as 3-(3-amino-3-carboxypropyl) uridine (a modified nucleoside in certain t-RNAs) were synthesized by the Ugi reaction by the use of the "op"-amine and appropriate aldehyde derived from uridine. Attempted synthesis of these nucleoside derivatives by the condensation involving (2-picolyl 1-oxide) isocyanide as well as the "op"-amine will be also touched on briefly.