Phosphinite-borane complexes

Figure 1.52. Racemic fullerenyl-substituted phosphane ( )-244, and stereoisomerically pure P-chiral fullerenyl-substituted phosphinites 245 and 246, obtained via addition to Cgo of diastereoisomerically pure, (+)-menthyl phosphinite-borane complexes 247 and 248, respectively.

Polymer-bound piperazine can also be used for the deprotection of phosphane-, phosphate- and phosphinite-borane complexes to give the corresponding free... 

The menthyl phosphonites and menthyl phosphinites were used for the preparation of F-chiral monodentate ligands. For example, Imamoto used menthyl phosphinite borane complexes for the synthesis of DIPAMP analogues, as shown in Scheme 6 [23]. The treatment of phosphinite borane (/ p)-8 with methyllithium. 

Scheme 1-42. Optically active phosphines from menthyl phosphinates (54) or menthyl phosphinite-borane complexes (55) by stereocontrolled R O/R displacement.

Treatment of Cjq with lithiated secondary phosphine boranes or phosphinite boranes followed by removal of the BHj group afforded 1,2-hydrophosphorylated 27 in good yields (Scheme 3.14) [114, 117]. The phosphorus nucleophiles were generated by deprotonation of the corresponding borane complexes with Bull in THF-HMPA, and added to toluene solutions of Cjq at -78 °C. Complexes 26 are stable in air at room temperature for months. In the NMR spectrum, the proton of 26b appears... 

Chiral phosphines are widely used as auxiliaries for various metal-catalyzed asymmetric reactions and can be prepared from stable phosphine-borane complexes. Secondary P-chiral phos-phine-boranes can be prepared by reductive lithiation of the corresponding tertiary phosphine-borane using LN (eq Likewise, P-chiral tertiary phosphine ligands can be produced by the reductive lithiation of phosphinite-boranes followed by alkylation, both proceeding with retention of configuration (eq 18). ... 

---