Abstract 2, 4, 7-Trioxa-3-chloro, 3-fluoro, 3-dimethylamino, 3-methoxy, 3-(2-propanoxy)-3- phospha-3-thionobi-cyclo (4.4. 0) decanes (trans fusion) have been prepared. The precursor diol, 2-hydroxymethyl-3-hydroxy-tetrahydropyran (2R∗, 3S∗), was obtained in two steps from 3, 4-dihydro-2H-pyran. The chloridates 7a and 7b were separated by high performance liquid chromatography and the stereochemistry of the nucleophilic substitution at ...