SYNTHESIS AND CONFIGURATIONAL ANALYSIS OF A NOVEL CLASS OF CAVITANDS CONTAINING 4 DIOXAPHOSPHOCIN MOIETIES

Synthesis, separation, and configurational analysis of diastereomeric cavitands having general structure I are described. The cavitands are obtained by incorporation of four phosphate groups on the all-cis-resorcin[4]arene. Four dioxaphosphocin rings with four stereogenic centers on the phosphorus(V) atoms are formed by bridging the eight phenolic functions. The reaction leads to all the six possible diastereoisomers having different orientations of the P=O groups either outward (o) or inward (i) with respect to the cavity. The separation of the different diastereoisomers of cavitands 3-12 was achieved by chromatographic methods and the configuration of each one elucidated with H-1, C-13, and P-31 NMR. Variation of the R(2) substituents on the phosphorus atoms was studied with the aim of a stereoselective formation of the iiii and iiio isomers which possess the best qualifications for multiple hydrogen-bonding interactions.