Synthesis And Reaction Mechanism Research Of New Pyrospirophosphoranes

Pentacoordinate phosphorus compounds as intermedinates or transition state species are proposed in numerous bioblogical processes. As a special type of pentacoordinate phosphorus compounds involving P-H bond. Hydrospirophosphorane is active enough to be precursors for organic synthesis. Until now, there were some reports about hydrophosphoranes, however, there was few research on hydrospirophosphoranes involving bi-amino acid unit. After the numerous bi-amino acid hydrospirophosphoranes were synthesized in our group, we studied in depth the Atherton-Todd reaction of bi-amino acid hydrospirophosphoranes with amine and phenol. In this paper, the chemical activity and the configuration of bi-valine Hydrospirophosphorane and bi-phenylalanine Hydrospirophosphorane to synthesize pyrospirophosphoranes were studied, and a probable mechanism was proposed in terms of experiments observations. Furemore, the relationship between the phosphorus configuration and the NMR spectrum data was explored and summarized.The synthesis of pyrospirophosphoranes from bi-valine Hydrospirophosphorane-A and bi-phenylalanine Hydrospirophosphorane-A were investigated. First, the effects of solvent, temperature, alkalis, halogenating agent and catalyst on the reaction were studied. Then in optimum conditions numerous new pyrospirophosphoranes were obtained in good yields. The structures of these new compounds were characterized by ESI-MS、 NMR and IR spectra. To explore the mechanism of the reaction, the single crystal of the intermediate was gained. The single crystal data suggested that the configuration of phosphorus chiral center of the intermediates was stereoretention. However, the configuration of the products depended upon the steric hindrance of substituent group and phosphorus configuration of bi-amino acid hydrospirophosphoranes. Only one configuration of pyrospirophosphorane from bi-valine Hydrospirophosphorane-A with smaller steric hindrance was obtained, while two diastereoisomers of pyrospirophosphoranes were produced, from bi-phenylalanine Hydrospirophosphorane-Awith bigger steric hindrance.In the process of research about the configuration of Atherton-Todd reaction between bi-amino acid hydrospirophosphorane with amine and phenol, since we were not able to determine the absolute configurations of phosphorus atoms, it is difficult to analyze clearly the change rule of configuration in the reaction. In this paper, we explored the relationship of the phosphorus configuration and spectrum character of pentacoordinate phosphorus compounds in the base of phosphorane whose absolute configuration could be confirmed by single crystal data. As a result, according to the spectrum character of some pentacoordinate phosphorus compounds, their absolute configurations might be determined.