Stereochemistry and Stability of Free and Coordinated Secondary Phosphines. Crystal and Molecular Structure of [S-[(R*,R*),(R*)]]-(+)589-[PtCl{1,2-C6H4(PMePh)2}(PHMePh)]PF6.cntdot.CH2Cl2

Synthesis and Stereoselective Interconversion of Chiral 1‐Aza‐3,6‐diphosphacycloheptanes

“…Thus, we have tried to evaluate whether or not M05-2X produces relative energies for the structural forms under study that are (Table 2), are in reasonable agreement with the data obtained from the B3LYP/6-31G* computations, which suggests a rather moderate role for the dispersion forces in the stereoconversion process studied. [29,30] The high rates of inversion for bisphosphanes 3-5 can be explained by the mechanism of this process. Each kinetic curve (Supporting Information) was plotted in the form Δc vs. t (with ca.…”

“…The inversion barriers for the phosphorus atoms of 1‐aza‐3,6‐diphosphacycloheptane 3 C( S ) (Table 3) are about 20 kcal/mol, which are noticeably lower than the typical values reported for tertiary phosphanes (30–38 kcal/mol) 29,30. The high rates of inversion for bisphosphanes 3 – 5 can be explained by the mechanism of this process.…”

Rhodium-Catalyzed Isomerization of a Bis(secondary phosphine) to an Unsymmetrical Diphosphine via P–C Cleavage and P–P and C–H Bond Formation

“…Notably, the initial reaction mixtures contained mixtures of diastereomers, as observed by 31 P­{ 1 H} NMR spectroscopy, but over several days, these mixtures evolved to yield single products. Presumably this process occurred by the known epimerization of P-stereogenic secondary phosphines, which is promoted by weak acids or bases, and has previously been used for similar resolution of secondary phosphines …”

Asymmetric Synthesis of P-Stereogenic Secondary Phosphine-Boranes by an Unsymmetric Bisphosphine Pincer-Nickel Complex

“…In particular, the development of privileged P-chiral phosphine ligands, such as CAMP, DIPAMP, Tangphos, QuinoxPhos, BIBPO, etc., opens up a new research area for achieving interesting asymmetric catalysis. − Continuous efforts have been deployed to develop effective methodologies for the preparation of P-stereogenic tertiary phosphines. − For example, the dynamic kinetic resolution of racemic secondary phosphines with alkyl or aryl halides affording P-chiral compounds has been investigated with chiral palladium, − platinum, − and ruthenium , complexes as catalysts. In addition, catalytic asymmetric additions of racemic secondary phosphines to benzoquinones or electron-deficient olefins − have been also exploited to produce P-stereogenic phosphines. − Compared to configurationally stable P-stereogenic tertiary phosphine, secondary phosphine is prone to racemization due to its low inversion barrier, which makes the synthesis of optically active secondary phosphine more difficult and challenging. The reported methods limit to the resolution of secondary phosphine chiral at phosphorus via recrystallization or using chiral auxiliaries. , Considering the importance of P-stereogenic secondary phosphines in serving as versatile building blocks for the divergent construction of chiral phosphorus ligands (Figure a) ,− , and transition metal complexes, , new catalytic asymmetric strategies to the construction of P-stereogenic secondary phosphines are highly desirable.…”

“…In addition, catalytic asymmetric additions of racemic secondary phosphines to benzoquinones 45 or electron-deficient olefins 46−48 have been also exploited to produce P-stereogenic phosphines. 49−51 Compared to configurationally stable P-stereogenic tertiary phosphine, secondary phosphine is prone to racemization due to its low inversion barrier, 52 which makes the synthesis of optically active secondary phosphine more difficult and challenging. The reported methods limit to the resolution of secondary phosphine chiral at phosphorus via recrystallization 53 or using chiral auxiliaries.…”