Synthesis of 2-D-L-Tryptophan by Sequential Ir-Catalyzed Reactions.

Herein, we report a practical synthesis of 2-D-L-tryptophan via sequential Ir-catalyzed C-H borylation, and Ir-catalyzed C-2-deborylative deuteration steps. In this synthetic sequence, deprotection of the Boc and methyl ester groups proved challenging, due to replacement of deuterium with hydrogen. However, mild deprotection conditions were developed to avoid this D/H scrambling. Further, 2-D-L-Tryptophan is stable in many buffers used for biological studies.