4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium Toluene-4-sulfonate (DMT/NMM/TsO-) Universal Coupling Reagent for Synthesis in Solution

4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium toluene-4-sulfonate (DMT/NMM/TsO-), a representative member of the inexpensive and environmentally-friendly N-triazinylammonium family of sulfonates, has been found to be a very effective coupling reagent for the synthesis of amides, esters and peptides in solution. This study confirms the usefulness of DMT/NMM/TsO- for peptide synthesis in solution, starting from Z-, Fmoc-, and Boc-protected substrates as well as unnatural building blocks. Peptide synthesis with DMT/NMM/TsO- produced high yields, with high crude product purity and low risk of racemization. In all cases, stoichiometric amounts of reagents were used and the standard synthetic procedure, without the need for time-consuming optimization stages or expensive chromatographic purification. DMT/NMM/TsO- was also found to be very useful for the synthesis of oligopeptides using a fragment coupling strategy.