Kazumasa Kajiyama

Characterization of an optically active pentacoordinate phosphorane with asymmetry only at phosphorus

Abstract By treating diastereomeric [o-OC(CF3)2C6H4]2PCH2CO2(−)menthyl] (2-(R)P and 2-(S)P) with LiAlH4, a pair of enantiomerically pure phosphoranes, [o-OC(CF3)2C6H4]2PCH2C2HOH (3-(R)P and 3-(S)P), having asymmetry only at phosphorus were obtained.

Non-dissociative permutation of a stable hydrophosphorane and retention of stereochemistry of the electrophilic reaction of its conjugate phosphoranide base

Abstract The permutation of [o- OC ∗ (CH 3 )(CF 3 )C 6 H 4 ][o- OC(CF 3 ) 2 C 6 H 4 ]PH was found to be a non-dissociative process with activation parameters of ΔH≠=ca.24.5 kcal mol−1 and ΔS≠=ca.−4 eu. The reaction of its conjugate base, phosphoranide [o- OC ∗ (CH 3 )(CF 3 )C 6 H 4 ][o- OC(CF 3 ) 2 C 6 H 4 ]P − , with ethyl chloroacetate was found to proceed with full retention of configuration.

Synthesis and characterization of intra- and intermolecular hydrogen bonding isomers of PH (apical) phosphoranes bearing a hydroxyl group and their thermal cyclization

Abstract The reaction of spirophosphorane 1 with 3 equivalents of RLi (R = Me, n-Bu, t-Bu) in Et2O at −78 °C followed by treatment with aq. HCl gave monocyclic PH phosphoranes 2–4 bearing an apical hydrogen atom in good yields. Particularly in the case of 4, an isomer 4a with intramolccular hydrogen bonding and an isomer 4b with intermolecular hydrogen bonding with a solvent molecule could be separately isolated. Monocyclic phosphoranes 2–4 cyclized intramolecularly with elimination of H2 to form spirophosphoranes 5–7 upon heating. Kinetic examination of cyclizations implied that they proceed via four-membered ring transition states involving hexacoordinate phosphorus.

First Isolations and Structures of cis -Bis(phosphoranido) Complexes

The first cis -bis(phosphoranido) palladium(II) and platinum(II) complexes were prepared by the reaction of a lithium phosphoranide, bearing two 8-oxy-1-naphthyl groups with (dmpe)MCl 2 (M; Pd, Pt). The crystal structures of the racemic isomers of the complexes are determined by the X-ray structural analyses.

Chiral HPLC Separation, Absolute Structural Elucidation, and Determination of Stereochemical Stability of trans‐Bis[2‐(2‐pyridinyl)aminophenolato] Cyclotriphosphazene

Chiral high-performance liquid chromatography (HPLC) separation of trans-bis[2-(2-pyridyl)aminophenolato] dichlorocyclotriphosphazene was achieved and the absolute configuration of was assigned to be S,S by single-crystal X-ray structural analysis. The optically pure 1,2-diphenyl-1,2-ethanediolate derivatives (+)- and (-)- were synthesized by the reactions of and with (R,R)-hydrobenzoin, respectively, in refluxing toluene in the presence of an excess amount of triethylamine and a catalytic amount of 4-(dimethylamino)pyridine. The racemization of the enantiomers of and the epimerization of diastereomers of 2 were not observed in refluxing toluene neither under acidic nor basic conditions. The stereochemistry of was confirmed by the crystal structure of (+)- and bis[(4-methyl-2-pyridyl)oxy]cyclotriphosphazene derived from . Chirality 28:556-561, 2016.

Preparation and Kinetic Study of Antiapicophilicity Pseudorotamers of Substituted Spirophosphoranes with Martin Ligand

Anti-apicophilic pseudorotamers bearing a Martin ligand with equatorial-O and apical-C, that isO-cis isomer, were prepared selectively. Kinetic study of BPR of O-cis isomer to O-trans isomer is discussed.