Synthesis and Reactions of Optically Active Secondary Dialkylphosphine-Boranes

A Comparative Study of Chalcogenated Phosphanylborohydrides[EPR2BH3]– (R = Ph, tBu) and Triorganophosphane Chalcogenides EPPh2CH3 (E = O, S, Se, Te)

“…[2] Given this background, it is interesting to explore whether replacement of an alkyl side-chain by the even less electronegative BH 3 fragment further promotes the capability of the phosphorus centre to deliver charge density to a coordinated acceptor atom. So far, the chemistry of such phosphanylborohydrides [PR 2 BH 3 ] -has not been systematically developed, although a number of publications already exist that clearly prove the potential of phosphanylborohydrides in areas as diverse as the synthesis of polymeric materials containing group 13 and group 15 elements, [3] the preparation of chiral organophosphanes, [4][5][6][7] general coordination chemistry, [8][9][10] and homogeneous catalysis. [11] Our group and EPPh 2 CH 3 , we come to the conclusion that the formal replacement of CH 3 + by BH 3 leads to a significant increase in the p character of the E-P bond, which therefore indicates that [PPh 2 BH 3 ] -is better suited to direct electron density towards an acceptor atom than its triorganophosphane congener PPh 2 3 .…”

Dialkylammonium tert-Butylmethylphosphinites: Stable Intermediates for the Synthesis of P-Stereogenic Ligands

“…13 Following the general procedure, 128 mg of methanesulfonic anhydride (0.71 mmol, 1.05 eq), 160 mg of 6 (0.68 mmol, 1 eq), 150 µL of N-methylmorpholine (1.36 mmol, 2 eq) and 8 mL of CH2Cl2 were used. 525 mg (2.04 mmol, 3 eq) of nBu4NBH4 in 2 mL of CH2Cl2 were added dropwise and the solution was stirred for 2 hours at -20ºC.…”

Synthesis of unsymmetrical P-stereogenic oligophosphines and chemoselective cleavage of phosphine-borane coordinate bonds

“…Wild and co-workers reported the syntheses and coordination behaviors of optically active P-stereogenic tetraphosphines and hexaphosphines, which were obtained by separating a mixture of stereoisomers by column chromatography and successive complexation with chiral palladium complexes. [17][18][19][20][21][22][23] Our group [14][15][16] and Imamoto's group [24][25][26][27][28][29] independently succeeded in synthesizing optically active P-stereogenic tetraphosphines ( Figure 1) through different synthetic routes. Imamoto et al 28 prepared their transition metal complexes, and the obtained complexes were used as chiral catalysts for transition metal-catalyzed asymmetric hydrogenations.…”