66875-71-6Relevant articles and documents
LIGANDS FOR SELECTIVE ASYMMETRIC HYDROFORMYLATION
-
Page/Page column 19-20, (2012/02/13)
In an aspect, the invention provides compounds of the formula 4: wherein the constituent variables are defined herein.
An asymmetric hydroformylation catalyst that delivers branched aldehydes from alkyl alkenes
Noonan, Gary M.,Fuentes, Jose A.,Cobley, Christopher J.,Clarke, Matthew L.
supporting information; experimental part, p. 2477 - 2480 (2012/04/18)
Surprising selectivity: The first enantioselective hydroformylations of simple alkenes of type RCH2CH=CH2 to preferentially deliver the branched aldehyde product have been discovered using a new chiral ligand, named bobphos (see scheme). Established ligands are unselective in this reaction or show a slight preference towards the linear aldehyde. Copyright
Highly enantioselective hydroformylation of olefins catalyzed by rhodium(I) complexes of new chiral phosphine-phosphite ligands
Nozaki, Kyoko,Sakai, Nozomu,Nanno, Tetsuo,Higashijima, Takanori,Mano, Satoshi,Horiuchi, Toshihide,Takaya, Hidemasa
, p. 4413 - 4423 (2007/10/03)
A new chiral phosphine-phosphite ligand, (R)-2-(diphenylphosphino)- 1,1'-binaphthalen-2'-yl (S)-1,1'-binaphthalene-2,2'-diyl phosphite [(R,S)- BINAPHOS, (R,S)-2a], was synthesized. Its Rh(I) complex was prepared, and its structure has been characterized by 1H and 31P NMR spectroscopy. Using Rh(I) complexes of (R,S)-2a and its enantiomer, highly enantioselective hydroformylation of styrene has been performed (94% ee, iso/normal = 88/12). The catalyst system was also effective for a variety of other olefins. Some other phosphine-phosphite ligands bearing 1,1'-binaphthyl and biphenyl backbones, such as (S)-3,3'-dichloro-6-(diphenylphosphino)-2,2',4,4'- tetramethylbiphenyl-6'-yl (R)-1,1'-binaphthalene-2,2'-diyl phosphite [(S,R)- BIPHEMPHOS. (S,R)-5a], (R,R)-2a, (R,S)-2b, (R)-2c, and (R)-5b, were tested for asymmetric hydroformylation. The results indicate that the sense of enantioface selection for the prochiral olefins is mainly determined by the absolute configuration of the phosphine site, for example, the (R)-2- (diphenylphosphino)-1,1'-binaphthalen-2'-yl group in (R,S)-2a. The relative configurations of the two biaryl groups in the phosphine-phosphites play crucial roles in the degree of the enantioselectivities, that is, the (R,S)- isomer generally gives products in high ee's and the (R*,R*)-isomer does in low ee's. Treatment of Rh(acac)[(R,S)-2a] with a 1:1 mixture of carbon monoxide and hydrogen gave a hydridorhodium complex. RhH-(CO)2[(R,S)-2a], as a single species. Trigonal bipyramidal structure is suggested for this complex, in which the hydride and the phosphite moiety are located at the apical positions and the phosphine and the two carbonyls occupy the equatorial positions. The interchange of the phosphine and the phosphite sites with each other through rapid pseudorotations has not been observed in RhH(CO)2[(R,S)-2a]. The structural deviations of the monohydride complexes from an ideal trigonal bipyramid seem to be larger in (R*,R*)-isomers than in the corresponding (R*,S*)-isomers. The existence of only one active species involved in the Rh(1)-(R,S)-2a-catalyzed hydroformylation has been manifested by the plot of ln([R]/[S]) of the hydroformylation product vs the reciprocals of the reaction temperatures. The higher thermodynamic stability of Rh(acac)[(R,S)-2a] than its diastereomer Rh(acac)[(R,R)-2a] is demonstrated in relation to the restricted configuration of (R)-2c to (R,S)- 2c in its complex formation with Rh(1).
Asymmetric hydroformylation catalyzed by an Rh( I) -( R,S) -BINAPHOS complex: Substituent effects in olefins on the regioselectivity
Nozaki, Kyoko,Nanno, Tetsuo,Takaya, Hidemasa
, p. 103 - 108 (2007/10/03)
Olefins bearing the larger substituants at the allylic position were hydroformylated in the higher iso/normal selectivity when Rh(I)-(R,S)-BINAPHOS was used as a catalyst. Deuterioformylation of 4,4,4-triphenyl-1 -butene suggests that the higher iso/normal ratio may be attributed to the accelerated CO insertion to the iso-alkylrhodium 7i.
Synthesis of New Chiral Phosphinephosphites Having 2-Diphenylphosphinobiphenyl-2'-yl Backbone and Their Use in Rh(I)-Catalyzed Asymmetric Hydroformylations
Higashizima, Takanori,Sakai, Nozomu,Nozaki, Kyoko,Takaya, Hidemasa
, p. 2023 - 2026 (2007/10/02)
New chiral phosphinephosphites (R)-(5,5'-dichloro-2-diphenylphosphino-4,4',6,6'-tetramethylbiphenyl-2'-yl)(S)-1,1'-binaphthalen-2,2'-diyl)phosphite and its enantiomer (S,R)-BIPHEMPHOS have been synthesized from 5,5'-dichloro-4,4',6,6'-tetramethyl-2,2'-biphenyldiol in enantiomerically pure form.Their Rh(I) complexes have been shown to be highly efficient catalysts for asymmetric hydroformylations of a variety of olefinic substrates.The corresponding phosphinephosphites derived from 2,2'-biphenyldiol were also tested as ligands for asymmetric hydroformylation.
