APPLICATIONS OF WITTIG OLEFINATION TOWARD THE SYNTHESIS OF FLUORESCENT SPHINGOSINE ANALOGS

Abstract

Over the last decade, a significant amount of research has been done on sphingosine-1-phosphate (S1P). S1P regulates survival, proliferation and migration of breast cancer cells45, as well as playing an important but still unknown role in ovarian46, prostate, and glioma47 cell carcinomas. S1P plays a significant role in the regulation, proliferation and angiogenesis, and is therefore an area of considerable interest for cancer research. Previous research in our group has shown that two stilbenoid sphingosine analogs (1 & 2) were effective at sphingosine kinase (SphK) inhibition in addition to showing down-regulation of Vascular Endothelial Growth Factor (VEGF), a novel and distinctly different mechanism of action compared to reported sphingosine kinase inhibitors. Both compounds showed novel toxicity toward the parasite Toxoplasma gondii. T. gondii causes toxoplasmosis; a disease carried by up to 1/3rd of the world’s population and one that has been implicated in schizophrenia. Unfortunately, use of 1 & 2 as fluorescent probes is limited; their emission wavelengths fall between 360 and 380 nm, within the range of background fluorescence. The synthesis of five fluorescent sphingosine analogs is described herein, three of which have emission wavelengths above 420 nm. These compounds show single digit µM cytotoxicity towards T. gondii. The second generation synthesis of Fingolimod (FTY720) is also described. The process was optimized for large-scale production. Improvements to the synthesis included increased atom economy, purification and overall reaction efficiency. Yield was increased to 36%, from 33% in the first generation synthesis. Lastly, a synthesis of p-divinylbenzene is described, using “green” solvents and easy sample work-up. The product contains no meta impurities, an issue that arises when p-divinylbenzene is purchased commercially.