Figure 4.

HPLC traces of the final reaction mixtures of 3 (0.4 mM) with b + c (each at 2 mM) (A and B) or c + d (each at 2 mM) (C and D) and NaBH₃CN (1.2 mM) in aqueous phosphate (20 mM, pH 6). (A and C) Traces correspond to the reaction without additive. (B and D) Traces correspond to the reaction in the presence of 1 equivalent (0.4 mM) of CA. Question marks indicate unidentified impurities.