Synthesis of the Alkylsulfonate Metabolites Cysteinolic Acid, 3-Amino-2-hydroxypropanesulfonate, and 2,3-Dihydroxypropanesulfonate

Chiral hydroxy- and aminohydroxysulfonic acids are widespread in the marine and terrestrial environment. Here we report simple methods for the synthesis of d - and l -cysteinolic acid (from (Boc- d -Cys-OH) 2 and (Boc- l -Cys-OH) 2, respectively), R - and S -3-amino-2-hydroxypropanesulfonate (from S - and R -epichlorohydrin, respectively), and R - and S -2,3-dihydroxypropanesulfonate (from S - and R -epichlorohydrin, respectively). d -Cysteinolate bile salts were generated by coupling with cholic and chenodeoxycholic acids. A series of single-crystal 3D X-ray structures confirmed the absolute configurations of the aminosulfonates. By comparison of optical rotation, we assign naturally occurring 3-amino-2-hydroxypropanesulfonate from Gateloupia livida as possessing the R -configuration. This simple synthetic approach will support future studies of the occurrence, chemotaxonomic distribution, and metabolism of these alkylsulfonates.