DNA-templated formation and N,O-transacetalization of N-methoxyoxazolidines have been studied. Compared to the reaction without a DNA-catalyst, the hybridization-driven N-methoxyoxazolidine formation shows a marked rate acceleration, whereas the rate of corresponding N,O-transacetalization is limited by the rate of decay to aldehyde intermediates. In both cases, the equilibrium yield increases markedly on the DNA template. Different hairpin architectures have been studied to evaluate the role and limits of the template effect. Furthermore, an attention has been paid to stereochemical integrity (R/S) of the N-methoxyoxazolidine linkage. The N-methoxyoxazolidine formation represents a dynamic pH-responsive DNA-templated ligation that occurs readily in slightly acidic conditions (pH 5).