Stereomutation and Experimental Determination of the Relative Stability of Diastereomeric O‐Equatorial Anti‐Apicophilic Spirophosphoranes

Abstract

A novel bidentate ligand based on 1,1,1,3,3,4,4,4-octafluoro-2-phenyl-2-butanol (16) has been used to synthesize a diastereomeric pair of hydrophosphoranes (18-exo and 18-endo). A comparison of the structures of a series of hydrophosphoranes (18-exo, 18-endo, 19, and 20-exo) obtained by X-ray crystallography indicated that the apical P-O bond lengths were affected by the electronic properties of the oxygen atom, which can be interpreted by the "single bond/no bond resonance" concept. From the hydrophosphoranes, Oapical (13-exo and 13-endo) and anti-apicophilic O-equatorial (12-exo and 12-endo) phosphoranes were synthesized.

Synthesis, structure, and reaction of tricoordinate stibine and tetracoordinate stiboranide

“…The experimental result that compound 1 did not react with MeI showed that the steric bulk of the pentafluoroethyl group could prevent the lone pair from attacking MeI. This result was similar to the reported result [42,45]. On the other hand, for compound 2a, the lone pair was sited in sp 2 orbital in the equatorial plane, and could react with MeI to give compound 4.…”

Frozen Dissymmetric Cavities in Resorcinarene‐Based Coordination Capsules

“…Activation parameters were obtained using an Eyring plot (Table and Figure S24, Supporting Information). The large negative entropic contributions of both solvents suggested that a unimolecular process appeared to be involved in the racemization process, in which two cavitand moieties of ( M )‐ 2 a (BF 4 ) 4 were partially dissociated, resulting in a distorted transition state with positive enthalpic contributions . The smaller enthalpic and entropic contributions of 1,2‐dichloroethane provided insight into the solvation characteristics of the transition state.…”

“…The large negative entropic contributions of both solvents suggested that au nimolecular process appeared to be involved in the racemization process,i nw hich two cavitand moieties of (M)-2a(BF 4 ) 4 were partially dissociated, resulting in ad istorted transition state with positive enthalpic contributions. [16] The smaller enthalpic and entropic contributionsof1,2-dichloroethane provided insight into the solvationc haracteristics of the transition state. 1,2-Dichloroethane moleculesa ggressively solvate to the partially undressed metal centers of the transition states;a s ar esult, the solvent molecules lose the freedom to move while the transition state is stabilized.…”

Crystallographic and NMR studies on species intermediate between haloalkoxyphosphoranes and alkoxyphosphonium halides

“…Hypervalent [1] phosphorus compounds (phosphoranes) have attracted significant interest and have thus been widely investigated [2,3]. Phosphoranes play important roles as intermediates in the phosphoryl transfer reaction [4] as well as in synthetic reactions such as the Wittig olefination [5].…”