Thiazolidine Derivatives from Fluorescent Dithienyl-BODIPY-carboxaldehydes and Cysteine
作者:Arnaud Poirel、Antoinette De Nicola、Raymond Ziessel
DOI:10.1021/jo502068u
日期:2014.12.5
Fluorescent dithienyl-borondipyrromethene (BODIPY) dyes formylated in the beta'-position (2b, 2c) have been treated with l-cysteine to provide thiazolidine derivatives. N-Protection of the thiazolidine unit by ethoxycarbonylation facilitated isolation of the two major diasteroisomers 6 and 7. These stereoisomers have been fully characterized by H-1 NMR spectroscopy, allowing assignment of their stereochemistry as 2R,4R,aS and 2S,4R,aR, respectively. The optical properties of the thiazolidine dyes differ markedly in both absorption (lambda(abs) = 612 nm for 6 and 615 nm for 7) and emission (lambda(em) = 669 nm, Phi F = 62% for 6 and lambda(em) = 672 nm, Phi F = 19% for 7) from those of the BODIPY-carboxaldehydes 2b (lambda(abs) = 643 nm and lambda(em) = 719 nm, Phi F = 26%) and 2c (lambda(abs) = 636 nm and pi(em) = 710 nm, Phi F = 36%). In a mixed solvent [phosphate buffer saline (PBS), pH = 7.4/ethanol 1:9], the fluorescence response of the dyes in the presence of l-cysteine is slow, but a ratiometric detection process in the therapeutic window (650 to 800 nm) is evident.