96929-98-5Relevant academic research and scientific papers
Regioselective rhodium-catalyzed hydroformylation of 1,3-dienes to highly enantioenriched β,γ-unsaturated aldehyes with diazaphospholane ligands
Watkins, Avery L.,Landis, Clark R.
supporting information; scheme or table, p. 164 - 167 (2011/04/12)
Regioselective and enantioselective rhodium-catalyzed hydroformylation of 1,3-dienes with chiral bisdiazaphospholane ligands yields β,γ- unsaturated aldehydes that retain a C=C functionality for further conversion. The reaction conditions are mild, featuring low catalyst loadings (0.5 mol %), pressures readily obtained in glass bottles, and convenient reaction times (1.5-12 h). Optimized reaction conditions produce high enantioselectivity (>90% ee), regioselectivity (88-99%), and conversion to β,γ- unsaturated aldehydes (99%) for ten 1,3-dienes encompassing a variety of substitution patterns.
Revisiting the Corey-Chaykovsky reaction: The solvent effect and the formation of β-hydroxy methylthioethers
Peng, Yu,Yang, Jin-Hui,Li, Wei-Dong Z.
, p. 1209 - 1215 (2007/10/03)
The classical Corey-Chaykovsky (CC) reaction of ketones in ethereal solvents (i.e., THF or Et2O) resulted in the production of a significant amount of β-hydroxy methylthioether 2 along with normal epoxide product 1. Some interesting and synthet
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 of conjugated dienes catalyzed by chiral phosphine-phosphite-Rh(I) complex
Horiuchi, Toshihide,Ohta, Tetsuo,Shirakawa, Eiji,Nozaki, Kyoko,Takaya, Hidemasa
, p. 7795 - 7804 (2007/10/03)
Asymmetric hydroformylation of conjugated dienes has been investigated using (R,S)-BINAPHOS-Rh(I) complex as a catalyst [(R,S)-BINAPHOS = (R)-2-(diphenylphosphino)-1,1'-binaphthalen-2'-yl (S)-1,1'-binaphthalene-2,2'-diyl phosphite]. Optically active β,γ-unsaturated aldehydes were obtained in high regio- (78-94%) and enantioselectivities (80-97% ee) from 1-vinylcyclohexene, 4-methyl-1,3-pentadiene, and (E)-1-phenyl-1,3-butadiene. On the other hand, hydroformylation of 1,3-butadiene gave achiral product, (E)- and (Z)-3-pentenal, in up to 95% selectivity. (R)-(E)-2-Methyl-3-pentenal was formed as the major product from both (E)- and (Z)-1,3-pentadiene, but enantioselectivity of the reaction was low. Mechanistic aspects are also discussed.
Asymmetric hydroformylation of conjugated dienes catalysed by [(R)-2-diphenylphosphino-1,1′-dinaphthalen-2′-yl] [(S)-1,1′-dinaphthalene-2,2′-diyl]phosphite-rhodium(I)
Horiuchi, Toshihide,Ohta, Tetsuo,Nozaki, Kyoto,Takaya, Hidemasa
, p. 155 - 156 (2007/10/03)
Asymmetric hydroformylation of conjugated dienes such as vinylcyclohexene, (E)-phenyl-buta-1,3-diene and 4-methyl-penta-1,3-diene using BINAPHOS-RhI complexes as catalysts {(R,S)-BINAPHOS = [(R)-2-diphenylphosphino-1,1′-dinaphthalen-2′-yl] [(S)-1,1′-dinaphthalene-2,2′-diyl]-phosphite} gives optically active β,γ-unsaturated aldehydes in high regio- (81-91%) and enantio-selectivities (84-97% ee).
Amphiphilic Reactions by Means of Exceptionally Bulky Organoaluminum Reagents. Rational Approach for Obtaining Unusual Equatorial, Anti-Cram, and 1,4 Selectivity in Carbonyl Alkylation
Maruoka, Keiji,Itoh, Takayuki,Sakurai, Minoru,Nonoshita, Katsumasa,Yamamoto, Hisashi
, p. 3588 - 3597 (2007/10/02)
Exceptionally bulky, oxygenophilic organoaluminum reagents, methylaluminum bis(2,6-di-tert-4-alkylphenoxide) (MAD and MAT), have been successfully utilized for stereoselective activation of carbonyl moiety.Combination of MAD or MAT with carbon nucleophiles such as organolithiums or Grignard reagents generates a new amphiphilic reaction system in which the alkylation may be interpreted as the nucleophilic addition of a reactive organometallic compound to an electrophilically activated carbonyl substrate in order to account for the regio- and stereochemical consequences.In contrast to the ordinary alkylations, the amphilic alkylation disclosed herein would be categorized into the new, yet unexplored class of alkylation that exhibits high chemoselectivity to carbonyl compounds, and more significantly it allows excellent equatorial and anti-Cram selectivity in carbonyl alkylations, hitherto difficult by the existing methodologies.Further, unusual conjugate addition of organolithium reagents to α,β-unsaturated carbonyl compounds has been accomplished by using the amphiphilic reaction system.
