Synthesis and application of a bidentate ligand based on decafluoro-3-phenyl-3-pentanol: steric effect of pentafluoroethyl groups on the stereomutation of O-equatorial C-apical spirophosphoranes.
1,1,1,2,2,4,4,5,5,5-Decafluoro-3-phenyl-3-pentanol was prepared by a Cannizzaro-type disproportionation reaction, and the dimetallated compound was used as a bidentate ligand, which is bulkier than the Martin ligand (1,1,1,3,3,3-hexafluoro-2-phenyl-2-propanol). A P-H spirophosphorane was synthesized by utilizing the new bidentate ligand, and the structure of the product was essentially the same as that of the P-H phosphorane with Martin ligands. Phosphoranes that exhibit reversed apicophilicity (O-equatorial) were also synthesized and could be converted into the corresponding stable stereoisomers (O-apical). The crystal structures of O-equatorial phosphoranes and the O-apical isomers were slightly affected by the steric repulsion of pentafluoroethyl groups. Kinetic measurements revealed that the stereomutation of O-equatorial methylphosphorane to the O-apical isomer was slowed. The activation enthalpy for the stereomutation of the former to the latter was higher than that of the phosphorane with Martin ligands by 5.1 kcal mol(-1).
Jiang
Xin-Dong
XD
Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima 739-8526, Japan.
Kakuda
Ken-ichiro
K
Matsukawa
Shiro
S
Yamamichi
Hideaki
H
Kojima
Satoshi
S
Yamamoto
Yohsuke
Y
D005466:Fluorocarbons / Q000737:chemistry; D008024:Ligands; D000439:Pentanols / Q000737:chemistry; D010753:Phosphoranes / Q000138:chemical synthesis* / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D005466:Fluorocarbons; D008024:Ligands; D000439:Pentanols; D010753:Phosphoranes; D013141:Spiro Compounds; C078256:pentafluoroethane