Limitations in Determining Enantiomeric Excess of Alcohols by 31P
... S,S) and two meso compounds (R,S and S,R), in a 2:1:1 ratio (Scheme 2). These diastereomers were detected by 31PNMR, as three signals (0-10 ppm). Application of Horeau’s equation1 (p2 = (K-1)/(K+1), where K = (peak area of threo / peak areas of meso 1 + meso 2 and p is the optical purity) allowed th ...
... S,S) and two meso compounds (R,S and S,R), in a 2:1:1 ratio (Scheme 2). These diastereomers were detected by 31PNMR, as three signals (0-10 ppm). Application of Horeau’s equation1 (p2 = (K-1)/(K+1), where K = (peak area of threo / peak areas of meso 1 + meso 2 and p is the optical purity) allowed th ...
- Sacramento - California State University
... PART ONE: INVESTIGATION OF SCHIFF BASES FOR THE VANADIUMCATALYZED ASYMMETRIC EPOXIDATION OF ALLYLIC ALCOHOLS ...
... PART ONE: INVESTIGATION OF SCHIFF BASES FOR THE VANADIUMCATALYZED ASYMMETRIC EPOXIDATION OF ALLYLIC ALCOHOLS ...
Full Article - PDF - Brandeis University
... The scope of the reaction was found to be extremely general. Clean kinetic resolutions of extraordinarily high enantioselectivities were attainable with a wide range of UNCAs bearing various substituents and protecting groups (Table 3). Using the same extractive procedure for the isolation of 3a and ...
... The scope of the reaction was found to be extremely general. Clean kinetic resolutions of extraordinarily high enantioselectivities were attainable with a wide range of UNCAs bearing various substituents and protecting groups (Table 3). Using the same extractive procedure for the isolation of 3a and ...
AddCorrections(KKH) - Spiral
... towards environmentally benign industrial processes make this an unattractive method for the addition of O–H to C=C bonds. The third route involves hydroboration of the C=C bond followed by oxidative cleavage of the trialkylborane intermediate, to provide the alcohol under mild reaction conditions ( ...
... towards environmentally benign industrial processes make this an unattractive method for the addition of O–H to C=C bonds. The third route involves hydroboration of the C=C bond followed by oxidative cleavage of the trialkylborane intermediate, to provide the alcohol under mild reaction conditions ( ...
研 究 業 績 リ ス ト
... (21) Novel Chiral Ligands, Diferrocenyl Dichalcogenides and Their Derivatives, for the Rh(I)- and Ir(I)-Catalyzed Asymmetric Hydrosilylation Y. Nishibayashi, J. D. Singh, K. Segawa, S. Fukuzawa, K. Ohe, S. Uemura Organometallics, 15, 370-379 (1996). (22) Enantioselective ortho-Lithiation of Substitu ...
... (21) Novel Chiral Ligands, Diferrocenyl Dichalcogenides and Their Derivatives, for the Rh(I)- and Ir(I)-Catalyzed Asymmetric Hydrosilylation Y. Nishibayashi, J. D. Singh, K. Segawa, S. Fukuzawa, K. Ohe, S. Uemura Organometallics, 15, 370-379 (1996). (22) Enantioselective ortho-Lithiation of Substitu ...
Electrochemical Investigations of W(CO) (L) and W(CO) (L) Complexes:
... moeity, such as Re(CO)3(LL), where LL = a polypyridyl ligand such as 2,2’-bipyridine (bpy), 1,10phenanthroline or related ligands, would be bridged to a non-emissive second metal center, W(CO)5 in this example, that undergoes reversible redox processes. Such compounds could potentially have “redox-t ...
... moeity, such as Re(CO)3(LL), where LL = a polypyridyl ligand such as 2,2’-bipyridine (bpy), 1,10phenanthroline or related ligands, would be bridged to a non-emissive second metal center, W(CO)5 in this example, that undergoes reversible redox processes. Such compounds could potentially have “redox-t ...
Direct production of hydrogen peroxide from CO, O2, and H2O over
... Table 1 shows the catalytic results for H2O2 production from CO/O2/H2O over several types of metal nanoparticles dispersed on alumina prepared by the wet reduction (WR) method, which has recently been shown to be an effective method for the preparation of various amorphous alloy catalysts for versati ...
... Table 1 shows the catalytic results for H2O2 production from CO/O2/H2O over several types of metal nanoparticles dispersed on alumina prepared by the wet reduction (WR) method, which has recently been shown to be an effective method for the preparation of various amorphous alloy catalysts for versati ...
Polyvalent Iodine in Synthesis (more than just Dess
... CAUTION Compound 1 was reported to be explosive by Meyer and more recently by J. B. Plumb and D. J. Harper, ICI Pharmaceuticals Group, in Chemical and Engineering News to be explosive similar to trinitrotoluene. The ICI preparation of 1, found to be explosive, had 43.5% iodine by elemental analysis ...
... CAUTION Compound 1 was reported to be explosive by Meyer and more recently by J. B. Plumb and D. J. Harper, ICI Pharmaceuticals Group, in Chemical and Engineering News to be explosive similar to trinitrotoluene. The ICI preparation of 1, found to be explosive, had 43.5% iodine by elemental analysis ...
t.h.e_2 - Homework Market
... ordering being sure to indicate the type and relative magnitude of intermolecular interactions (e.g. VDW interactions, dipole-dipole, and hydrogen bonding) that exist in each case. ...
... ordering being sure to indicate the type and relative magnitude of intermolecular interactions (e.g. VDW interactions, dipole-dipole, and hydrogen bonding) that exist in each case. ...
Poly(ethylene glycol)-supported a,a,a
... effective catalyst in dioxirane mediated alkene epoxidation reactions and that is approximately as efficient as is the analogous small molecule ketone, a,a,a-trifluoroacetophenone.18,33,34 Due to its solubility, 2 functions as a homogeneous catalyst and, therefore, allows for much shorter reaction times ...
... effective catalyst in dioxirane mediated alkene epoxidation reactions and that is approximately as efficient as is the analogous small molecule ketone, a,a,a-trifluoroacetophenone.18,33,34 Due to its solubility, 2 functions as a homogeneous catalyst and, therefore, allows for much shorter reaction times ...
Reductive Coupling Reactions of Nitrones and Imines
... examples suggest the necessity for balancing the activation of the substrates and the strength of the reductant for efficient cross coupling. The steric bulk of the Į-substituents on the imine also plays a role in substrate reactivity. Cross coupling of N-benzylideneaniline with diethyl ketone using ...
... examples suggest the necessity for balancing the activation of the substrates and the strength of the reductant for efficient cross coupling. The steric bulk of the Į-substituents on the imine also plays a role in substrate reactivity. Cross coupling of N-benzylideneaniline with diethyl ketone using ...
Pincer Complexes. Applications in Catalysis
... only afforded 1.8 turnovers at 200 oC. Further experiments, led Jensen and coworkers [21] to determine that it was in fact the iridium derivative IrH2{C6H3-2,6-(CH2PBut2)2} (13) and not the rhodium complex (12) the best dehydrogenation catalyst. Thus, under the optimized conditions Jensen and cowork ...
... only afforded 1.8 turnovers at 200 oC. Further experiments, led Jensen and coworkers [21] to determine that it was in fact the iridium derivative IrH2{C6H3-2,6-(CH2PBut2)2} (13) and not the rhodium complex (12) the best dehydrogenation catalyst. Thus, under the optimized conditions Jensen and cowork ...
Abstract OXIDATIVE TRANSFORMATIONS AND CYCLIZATIONS
... their corresponding nitro compounds in good yields. Aromatic amines with electronwithdrawing groups gave lower conversions, however increasing the catalyst loading to 20 mol% led to an improvement in the product formation. In all the cases, nitro derivatives are found to be the sole products. This m ...
... their corresponding nitro compounds in good yields. Aromatic amines with electronwithdrawing groups gave lower conversions, however increasing the catalyst loading to 20 mol% led to an improvement in the product formation. In all the cases, nitro derivatives are found to be the sole products. This m ...
New Phenylglycine-Derived Primary Amine Organocatalysts for the
... anticipated by us that introducing sterically more demanding side chains through cyclohexylglycine or tert-leucine (amino alcohols 16–17) would enhance the enantioselectivity even further, a hypothesis obviously invalidated by experiment. Clearly, the presence of an aromatic moiety is crucial. Among ...
... anticipated by us that introducing sterically more demanding side chains through cyclohexylglycine or tert-leucine (amino alcohols 16–17) would enhance the enantioselectivity even further, a hypothesis obviously invalidated by experiment. Clearly, the presence of an aromatic moiety is crucial. Among ...
[Ru(Triphos)H2(CO)] Characterisation - Durham e
... reducing conditions of reactions, such as hydrogenation or hydroformylation, causing the precipitation of the metal, a problem encountered with the heavier transition ...
... reducing conditions of reactions, such as hydrogenation or hydroformylation, causing the precipitation of the metal, a problem encountered with the heavier transition ...
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... development in transition-metal catalysis in the past few years.20 The high activity of the iridium catalysts in N-alkylation reactions, combined with the excellent performance of NHCs as ligands in homogeneous catalysis, inspired us to seek an easily accessible and highly active NHC-based iridium c ...
... development in transition-metal catalysis in the past few years.20 The high activity of the iridium catalysts in N-alkylation reactions, combined with the excellent performance of NHCs as ligands in homogeneous catalysis, inspired us to seek an easily accessible and highly active NHC-based iridium c ...
102 Lecture Ch15
... - no matter how you turn them, they can’t be superimposed • Many organic compounds are also chiral - most biomolecules (amino acids, sugars, etc.) are chiral and usually only one of the stereoisomers is used • In order for a carbon in an organic compound to be chiral, it must have 4 different groups ...
... - no matter how you turn them, they can’t be superimposed • Many organic compounds are also chiral - most biomolecules (amino acids, sugars, etc.) are chiral and usually only one of the stereoisomers is used • In order for a carbon in an organic compound to be chiral, it must have 4 different groups ...
University of Groningen Manganese catalysts in
... 8) excellent results (894 t.o.n.’s) were found with selectivities up to 99% to the corresponding ketones. For 4-trifluoromethyl benzylalcohol lower selectivities were observed (entry 4). Perhaps over-oxidation to benzoic acid takes place, however, this was not quantified. Other secondary alcohols li ...
... 8) excellent results (894 t.o.n.’s) were found with selectivities up to 99% to the corresponding ketones. For 4-trifluoromethyl benzylalcohol lower selectivities were observed (entry 4). Perhaps over-oxidation to benzoic acid takes place, however, this was not quantified. Other secondary alcohols li ...
127 - Chimica
... only to the third metal atom, Os(2)-N = 2.15 (1)A. q2Carbene ligands are very unusual but have been observed previously in some mononuclear21and dinuclear22metal complexes. The compound Ru,(CO),(dppm)(p3CHPPh2)(p3-PPh)contains a triply bridging C(H)PPh2 ligand which could be viewed as a (diphenylpho ...
... only to the third metal atom, Os(2)-N = 2.15 (1)A. q2Carbene ligands are very unusual but have been observed previously in some mononuclear21and dinuclear22metal complexes. The compound Ru,(CO),(dppm)(p3CHPPh2)(p3-PPh)contains a triply bridging C(H)PPh2 ligand which could be viewed as a (diphenylpho ...
Organocatalysed asymmetric Mannich reactions
... So far, only proline was used in the asymmetric threecomponent Mannich reaction. Córdova and co-workers reported the use of alternative linear chiral amines and amino acids to catalyse the direct Mannich reaction with high enantioselectivities (Scheme 15).16 By stirring 39, p-anisidine (6), p-nitr ...
... So far, only proline was used in the asymmetric threecomponent Mannich reaction. Córdova and co-workers reported the use of alternative linear chiral amines and amino acids to catalyse the direct Mannich reaction with high enantioselectivities (Scheme 15).16 By stirring 39, p-anisidine (6), p-nitr ...
Reductive etherification of substituted cyclohexanones with
... having bulky substituents at the 4-position, using secondary alcohols as reductants. The zeolite appears to be active for both acid-catalysed conversion of the ketones to (hemi)acetals and consecutive Meerwein–Ponndorf–Verley (MPV)-type hydride transfer to yield ethers. Until now two catalysts were ...
... having bulky substituents at the 4-position, using secondary alcohols as reductants. The zeolite appears to be active for both acid-catalysed conversion of the ketones to (hemi)acetals and consecutive Meerwein–Ponndorf–Verley (MPV)-type hydride transfer to yield ethers. Until now two catalysts were ...
Microwave Irradiation for the Facile Synthesis of
... 10b in Table 1). No significant change in particle size and distribution was evident. The dispersions are stable for more than six months under an argon atmosphere. Under air the black, magnetic Fe (from conventional heating) and Co dispersions change their color and lose their magnetic properties.[ ...
... 10b in Table 1). No significant change in particle size and distribution was evident. The dispersions are stable for more than six months under an argon atmosphere. Under air the black, magnetic Fe (from conventional heating) and Co dispersions change their color and lose their magnetic properties.[ ...
"Introduction" Kinetics in Process Chemistry: Case Studies Baran Group Meeting Mike DeMartino
... -While there aren't a tremendous amount of these "problem-solving through kinetics" stories out there, the ones that are out there are typically beautiful pieces of work. They elegantly solve problems logically, that may well have taken a very long time if attempted though the more discovery-minded ...
... -While there aren't a tremendous amount of these "problem-solving through kinetics" stories out there, the ones that are out there are typically beautiful pieces of work. They elegantly solve problems logically, that may well have taken a very long time if attempted though the more discovery-minded ...
The bite angle makes the catalyst
... angles. The ¯exibility range is de®ned as the bite angles that can be reached within an energy barrier of 3 kcal/mol. In the actual calculation a `dummy'-type atom is used for the metal atom with no de®ned geometry and a typical M-P bond length known from X-ray structures of similar complexes. The f ...
... angles. The ¯exibility range is de®ned as the bite angles that can be reached within an energy barrier of 3 kcal/mol. In the actual calculation a `dummy'-type atom is used for the metal atom with no de®ned geometry and a typical M-P bond length known from X-ray structures of similar complexes. The f ...
Asymmetric hydrogenation
Asymmetric hydrogenation is a chemical reaction that adds two atoms of hydrogen preferentially to one of two faces of an unsaturated substrate molecule, such as an alkene or ketone. The selectivity derives from the manner that the substrate binds to the chiral catalysts. In jargon, this binding transmits spatial information (what chemists refer to as chirality) from the catalyst to the target, favoring the product as a single enantiomer. This enzyme-like selectivity is particularly applied to bioactive products such as pharmaceutical agents and agrochemicals.