SYNTHESE ET PROPRIETES DE NOUVEAUX SPIROPHOSPHORANES. REACTION DES DIOXA ET OXAZAPHOSPHOLANES AVEC L'AZODICARBOXYLATE D'ETHYLE

Mechanism of Phosphorus-Carbon Bond Formation in the Amidoalkylation of Phosphonous Carboxylic Acids

An unusual greater reactivity of phosphonous propionic acids was found in comparison with phosphonous propionic esters in carbamate version of Kabachnik-Fields reaction. Compounds of tricoordinated phosphorus generated in situ during the amidoalkylation of hydrophosphorylic compounds in acetyl chloride/acetic anhydride mixture were found by ³¹P NMR analysis. A hypothesis is proposed about the generation of spirophosphoranes in situ to explain the mechanism for the formation of the phosphorus-carbon bond in the reaction under study.

Biologically relevant phosphoranes: structural characterization of a nucleotidyl phosphorane

The first successful crystal structures of biorelevant nucleoside and carbohydrate-based phosphoranes are reported. Employing thymidine, a nucleotidyl phosphorane was synthesized in 90% yield and was shown by X-ray analysis to possess a trigonal bipyramidal geometry. With the use of 1,2-O-isopropylidene-alpha-d-glucofuranose, a carbohydrate-based phosphorane was formed and similarly found to have a trigonal bipyramidal geometry. NMR studies demonstrated the existence of isomerism in solution associated with the nucleotidyl phosphorane and rapid exchange for the carbohydrate-based phosphorane. The geometrical representations reported here are expected to have significant applications associated with active site mechanisms of phosphoryl transfer enzymes, for example, in DNA, RNA, c-AMP, and others.