M 2518 (OTTO) 2-Mesitylenesulfonyl chloride, 99% Cas 773-64-8 - used as reagent for intramolecular lactamizations and lactonization. It also acts as a reagent for protecting guanidino groups and tryptophan. M 2518 (OTTO) 2-Mesitylenesulfonyl chloride, 99% Cas 773-64-8 - used as coupling reagent in polynucleotide synthesis.