Synthesis and evaluation of photolabile sulfonamides as potential reagents for rapid photorelease of neuroactive amines

Abstract

The synthesis is described of photolabile sulfonamide derivatives of amino acids, most of which incorporate a monophosphate ester to promote water solubility. Points of particular synthetic interets include observations on the reduction of diaryl ketones and diarylmethanols, e.g. compounds 7 and 9, with NaBH₄–TFA, and a convenient, effective sequence for conversion of bromoarenes into arenesulfonyl halides, e.g. 10 → 13. Photolysis of the glycine derivative 18a in aqueous solution released free glycine in poor yield, except in the presence of a very large excess of ascorbate as a reducing agent. The likely cause is discussed in terms of a decarboxylation side-reaction occurring during the overall progress of the photocleavage.