On the solvolysis kinetics of amidoesters derived from β-aminoalcohols

To better understand reactivity in such systems, fifteen amidoesters derived from β-aminoalcohols were solvolyzed at the ester group in mildly basic methanol-d4. All trials showed pseudo-first-order kinetics by 1H NMR. The rate constants are about 2 to 140-fold larger than those found with simple alkyl esters. The least bulky N-acyl groups generally sponsor the largest rate constants, and strongly so in two cases, but apparently not as a result of lesser steric crowding between the amide and ester groups. Rate constants are also greater for those amidoesters favoring an anti conformation at the amide linkage.

Fifteen amidoesters derived from β-aminoalcohols were solvolyzed at the ester group in mildly basic methanol-d4 while monitoring by 1H NMR. The amide group was found to activate the ester group by about 2 to 140-fold relative to simple alkyl esters. The specific identity of the N-acyl group has a significant impact on the degree of activation in some cases. The nature of the structure-reactivity relationship is discussed.