Efficient Asymmetric Synthesis of Tryptophan Analogues Having Useful Photophysical Properties

Two new fluorescent probes of protein structure and dynamics have been prepared by concise asymmetric syntheses using the Schollkopf chiral auxiliary. The site-specific incorporation of one probe into dihydrofolate reductase is reported. The utility of these tryptophan derivatives lies in their absorption and emission maxima which differ from those of tryptophan, as well as in their large Stokes shifts and high molar absorptivities.