Functional Phosphine Derivatives Having Stationary and Flexible Chiralities: Their Preparation and Chirality Controlling

Abstract

Various functional secondary and tertiary phosphines, or their derivatives, containing stationary chiral phosphorus and flexible chiral axis were prepared, which could be further modified to afford diversely chelating ligands. The flexible axial chirality was fixed by stereogenic phosphorus via a cyclic linkage of chemical bonds or coordination with a metallic ion.

Coordination chemistry and catalysis with secondary phosphine oxides

“…8,50 The use of menthylphosphinates as chiral auxiliaries in the preparation of Pstereogenic SPOs is relatively well developed. 51 The first synthesis of a P-stereogenic SPO was reported in 1968, 15 when benzylphenylphosphine oxide was prepared by reduction of the corresponding menthol-precursor with lithium aluminium hydride (Scheme 12).…”

The stereoselective conversion of epimerized alkoxyl phosphine–borane to P,C, axial-stereogenic tertiary phosphine via cleavage of P–O bond

“…When a cyclic starting material was used, a hydroxyl in the product could be successfully used to This research started from CDOP (6-chloro-6H-dibenzo [c, e][1,2]oxaphosphinine) 1, which reacted with (L)-menthyl magnesium chloride to afford 2a (Scheme 1). 15 Two multi-peaks at 112.1 and 109.7 ppm on the 31 P NMR spectrum, in a ratio of approximately 50 : 50, were assigned as two stereoisomers 2a/ 2a′ deriving from chiral phosphorus.…”

“…The preparation of R P - 5 from epimerized 2a/2a′ was obviously better than in previous reports using enantiopure 2a . 15 When methyl iodide was used, 5aa was obtained with a poorer 86 : 14 dr than alkyl bromides (entry 1). n -Butyl chloride gave 5ac in better dr, but the reaction took place sluggishly (entry 4).…”

Cleavage of Aromatic C–O Bonds via Intramolecular SNAr Reaction and Preparation of P,C,Axial-Stereogenic Menthyl Phosphine Derivatives

“…Both O,P-methylated products were not detected when 1 equiv of KOH was used (see Scheme 2A). 19 Treatment of 5 with oxalyl chloride, followed by reaction with Grignard reagents at −80 °C and the addition of borane, afforded 6. During the process, the R P -and S P -stereoisomers of 5 were converted to R P -6; thus, the four stereoisomers were converted to two stereoisomers that were derived f rom the chiral axis.…”

“…The 31 P NMR spectrum indicated that 5 also was formed as a mixture of four stereoisomers. Both O , P -methylated products were not detected when 1 equiv of KOH was used (see Scheme A) …”