Abstract
1J(31P15N) coupling constants of R p and S p adeno-sine cyclic 3′,5′-phosphoramidates (1), -N-methylphosphor-amidates (2) and -N,N-dimethylphosphoramidates (3) increase in the order of 1<2<3 and obey the Stec rule (J(R p)< J(S p)). A possible interpretation of coupling constant differences based on differences in substituent electronegativities and variation in hybridization at nitrogen atom, is suggested.