The first structural study on a cyclic tricoordinate phosphorochloridite and a pentacoordinate phosphorane based on 1,2,3,5-protected myo-inositol-a new conformation of 1,3,2-dioxaphosphorinane ring

Abstract

Treatment of the phosphoramidite {myo-C₆H₆-2-[OC(O)Ph]-1,3,5-(O₃CH)-4,6-(O₂P-NH-i-Pr)} with o-chloranil affords the first example of inositol-based pentacoordinate phosphorane {myo-C₆H₆-2-[OC(O)Ph]-1,3,5-(O₃CH)-4,6-(O₂P-NH-i-Pr)(1,2-O₂C₆Cl₄)} (9) (X-ray structure) with a trigonal bipyramidal geometry at phosphorus. The six-membered 1,3,2-dioxaphosphorinane ring with the inositol residue has an unusual boat conformation in 9 which is quite different from that found in unrestrained rings investigated before, but is similar to that of its P^III chloro precursor {myo-C₆H₆-2-[OC(O)Ph]-1,3,5-(O₃CH)-4,6-(O₂PCl)} (X-ray structure). Also, a convenient and chromatography-free procedure for the protected myo-inositol derivative {myo-C₆H₆-2-[OC(O)Ph]-1,3,5-(O₃CH)-4,6-(OH)₂} is reported.