Propylphosphonic anhydride (T3P^®) is a very efficient, nontoxic coupling reagent especially suited for connecting sterically hindered amino acids. A further advantage is the easy removal of byproducts by extraction of the crude product with water.

Mukaiyama introduced pyridinium reagents like 2-chloromethylpyridinium iodide to peptide chemistry, which found application in the synthesis of a b-lactam carbacepham skeleton.

Cyanuric chloride has been used for the preparation of acyl chlorides, amides and peptides. The cyanuric chloride derivative CDMT (2-chloro-4,6-dimethoxy-1,3,5-triazine) yields highly reactive esters with carboxylic acids that can then be used as powerful acylating agents for amines and the less nucleophilic, alcohols.  The activation is performed in presence of a base, preferentially NMM (N-methylmorpholine). In situ NMM and CDMT form the intermediate DMTMM. DMTMM can be isolated and used as coupling reagent independently.  In contrast to CDMT, DMTMM does not require pre-activation of the carboxylic acid. The coupling efficiency of DMTMM in SPPS was found to be comparable to PyBOP while racemization could be kept below the detection limit.