Popis: |
Care should be taken when using amino acid ionic liquids (AAILs) for organic synthesis because of their multiple reactive groups. To expand the applicability of AAILs, we prepared a series of room-temperature ionic liquids derived from commercially available tert-butyloxycarbonyl-protected amino acids (Boc-AAILs). The resulting protected AAILs were used as the starting materials in dipeptide synthesis with commonly used coupling reagents. The distinctive coupling reagent N,N′-diethylene-N′′-2-chloroethyl thiophosphoramide was found to enhance amide formation in the Boc-AAILs without addition of base, giving the dipeptides in satisfactory yields in 15 min. |