CONCERTED GROB FRAGMENTATION IN N-HALO-ALPHA-AMINO ACID DECOMPOSITION

The Grob fragmentation of N-halo-alpha-amino acids in aqueous solution has been studied, being first order in N-halo-alpha-amino acid and pH-independent. The substituents on the C-2 and N atoms strongly affect the reaction rate. Structure reactivity correlations for C-2 substituents provide rho* values of -3.9 and -4.1 for N-Cl and N-Br compounds, respectively. The same correlations for N substituents lead to rho* values of -2.1 and -1.9 for N-Cl and N-Br compounds. The transition state (TS) can be generally described as product-like, its structure and characteristics being significantly affected by the substituents on the C-2 and an the N atoms. In conclusion, the reaction is a DEDN concerted and slightly nonsynchronous two-stage process.