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 Original Research Article

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 PIII 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.