Cu(II)-catalyzed enantioselective oxygen atom transfer from oxaziridine to oxindole derivatives with chiral phenanthroline
Naganawa, Y.; Aoyama, T.; Nishiyama, H.Org. Biomol. Chem.2015,13, 11499-11506 (DOI: 10.1039/C5OB01840D, 02 Oct 2015)In the presence of a Cu(II) complex of axially chiral, N,N,O-tridentate phenanthroline ligand (S)-2, asymmetric oxygen atom transfer of oxindole derivatives (3) using Davis’ oxaziridine (4) occurred to give the corresponding 3-aryl-3-hydroxy-2-oxindole derivatives (1) with excellent enantioselectivity (up to 96% ee). The X-ray crystallographic analysis of the isolated Cu(II) complex disclosed its N,N,O-tridentate coordination, which is critical to realize effective catalytic activity.Highlighted inSynfacts 2015; 11(12): 1276
Zinc-catalyzed Enantioselective Electrophilic Amination of β-Ketocarbonyl Compounds with Axially Chiral Phenanthroline Ligands
Naganawa, Y.; Komatsu, H.; Nishiyama, H.Chem. Lett.2015,44, 1652-1654. (doi:10.1246/cl.150802).Zinc-catalyzed asymmetric α-amination of β-ketocarbonyl compounds 2 using dialkyl azodicarboxylates 3 as the electrophilic nitrogen source was described. The complexes of Zn(OTf)2 and the axially chiral phenanthroline ligands (S)-1 were discovered as effective catalysts for this transformation to provide α-amino-β-ketocarbonyl compounds 4 with up to 93% ee.
Construction of a Chiral Silicon Center by Rhodium-Catalyzed Enantioselective Intramolecular Hydrosilylation
Naganawa, Y.; Namba, T.; Kawagishi, M.; Nishiyama, H.Chem. Eur. J.2015,21, 9319-9322.DOI: 10.1002/chem.201501568Rhodium-catalyzed enantioselective desymmetrizing intramolecular hydrosilylation of symmetrically disubstituted hydrosilanes is described. An axially chiral N,N,O-tridentate phenanthroline ligand (BinThro) is found to form an effective chiral catalyst for this transformation, providing cyclic five-membered organosilanes with chiral silicon centers with up to 91% ee.
Asymmetric synthesis of optically active 3-amino-1,2-diols from N-acyl-protected allylamines via catalytic diboration with Rh[bis(oxazolinyl)phenyl] catalysts
Toribatake, K.; Miyata, S.; Naganawa, Y.; Nishiyama H.Tetrahedron.2015,71,3203-3208.doi:10.1016/j.tet.2015.04.011Asymmetric diboration of N-acyl-protected allylamines such as substituted imides, amides, and carbamates catalyzed by chiral rhodium[bis(oxazolinyl)phenyl] complexes followed by oxidation in one-pot was realized to produce optically active 3-amino-1,2-propanediol derivatives in high enantioselectivities up to 99%.
Design of novel chiral N,N,O-tridentate phenanthroline ligands and its application to enantioselective addition of organozinc reagents to aldehydes
Naganawa, Y.; Namba, T.; Aoyama, T.; Shoji, KL.; Nishiyama, H.Chem. Commun.2014,50, 13224-13227.DOI: 10.1039/C4CC05020GThe novel N,N,O-tridentate phenanthroline ligands (BinThro) bearing axially chiral binaphthyl backbone prepared from BINOL were found to be an effective chiral catalyst for enantioselective addition of diethylzinc to aromatic aldehydes with high enantioselectivity (up to 95% ee).
Asymmetric diboration of terminal alkenes with rhodium catalyst and subsequent oxidation: Enantioselective synthesis of optically active 1,2-diols
Toribatake, K.; Nishiyama, H.Angew. Chem. Int. Ed.2013, 52, 11011-11015.DOI: 10.1002/anie.201305181A highly enantioselective diboration of terminal alkenes with chiral 1 and bis(pinacolato)diboron (B2pin2) was realized. Subsequent oxidation of the diboron adducts with sodium peroxoborate readily gave the corresponding optically active 1,2-diols in high yields and high enantioselectivities.Highlighted in Synfacts,2014, 10(1), 0050.DOI: 10.1055/s-0033-1340442.
Hosokawa, S.; Ito, J.; Nishiyama,Organometallics2013,32, 3980-3985.DOI: 10.1021/om400450nWe describe the preparation and characterization of new NCN-pincer Co(III) complexes containing bis(oxazolinyl)phenyl (phebox) ligands as auxiliary ligands. The reaction of Co2(CO)8with the 2-bromo-substituted ligand precursor (phebox-R)Br resulted in the formation of the tricarbonyl Co(I) complexes (phebox-R)Co(CO)3. Complexes 2 underwent oxidative addition of I2to give the Co(III) aqua complex (phebox-R)CoI2(H2O) by a change in the coordination geometry to the NCN-tridentate mode.
Asymmetric α-boration of α,β-unsaturated carbonyl compounds with chiral Rh[bis(oxazolinyl)phenyl] catalysts
Toribatake, K.; Zhou, L.; Tsuruta, A.; Nishiyama, H.Tetrahedron,2013,69, 3551-3560.DOI:10.1016/j.tet.2013.02.086Chiral rhodium[bis(oxazolinyl)phenyl] complexes exhibited high catalytic activity for the α-boration of α,β?unsaturated esters, ketones, and amides with bis(pinacolato)diboron in the presence of sodium t-butoxide to attain high enantioselectivity of up to 97%. The substrate scope and catalytic mechanism were discussed.Highlighted inSynfacts,2013,9(7), 0736.DOI: 10.1055/s-0033-1339164
Direct Conjugate Addition of Alkynes witha,b-Unsaturated Carbonyl Compounds Catalyzed by NCN Pincer Ru Complexes
Ito, J.; Fujii, K.; Nishiyama, H.Chem. Eur. J.,2013,19, 601-605.DOI: 10.1002/chem.201203380NCN pincer Ru complexes containing bis(oxazolinyl)phenyl ligands serve as suitable catalysts in direct conjugate additions of α,β-unsaturated carbonyl compounds, including ketones, esters, and amides, as well as vinylphosphonates, giving various β-alkynyl carbonyl and phosphonate compounds. A phebox Ru complex also catalyzes asymmetric conjugate addition of an alkyne with a β-substituted, α,β-unsaturated ketone to produce a chiral β-alkynyl ketone.
Enantioselective Synthesis of Optically Active 3,3-Diarylpropanoates by Conjugate Hydrosilylation with Chiral Rh-bis(oxazolinyl)phenyl Catalysts
Itoh, K.; Tsuruta, A.; Ito, J.; Yamamoto, Y.; Nishiyama, H.J. Org. Chem.2012,77, 10914-10919.DOI: 10.1021/jo302357bConjugate hydrosilylation of 3,3-diarylacrylate derivatives catalyzed by chiral rhodium-bis(oxazolinyl)phenyl complexes (1 mol %) at 60 °C for 2 h was investigated to prepare optically active 3,3-diarylpropanoate derivatives in high yields up to 99% yield and high enantioselectivities up to 99%.
Intermolecular C?H Bond Activation of Alkanes and Arenes by NCN Pincer Iridium(III) Acetate Complexes Containing Bis(oxazolinyl)phenyl Ligands
Ito, J.; Kaneda, T.; Nishiyama, H., Organometallics2012,31, 4442-4449.DOI: 10.1021/om3002137Carbon?hydrogen bond activation of arenes by the pincer Ir(III) acetate complex (phebox)Ir(OAc)2(H2O) (1) proceeded at 100 °C to give the corresponding aryl Ir(III) complexes (phebox)Ir(Ar)(OAc) in high yields. The Ir complex1underwent catalytic borylation of arenes with bis(pinacolato)diboron (B2(pin)2) or pinacolborane (HB(pin)), giving the corresponding borylated products. The Ir complex 1 also underwent alkane C?H bond activation of n-alkanes, giving the alkyl complexes.
Change in Coordination of NCN Pincer Iron Complexes Containing Bis(oxazolinyl)phenyl Ligands
Enhancement of enantioselectivity by alcohol additives in asymmetric hydrogenation with bis(oxazolinyl)phenyl ruthenium catalysts
Jun-ichi Ito, Tomoki Teshima and Hisao Nishiyama,Chem. Commun.2012,48, 1105-1107DOI: 10.1039/C1CC16057EBis(oxazolinyl)phenyl ruthenium(II) complexes were found to catalyze asymmetric hydrogenation of ketones, in which chiral bulky alcohol additives showed significant enhancement of enantioselectivity even in protic solvents.
Asymmetric Iron-Catalyzed Hydrosilane Reduction of Ketones: Effect of Zinc Metal upon the Absolute Configuration
Inagaki, T.; Ito, A.; Ito, J.; Nishiyama, H.Angew. Chem. Int. Ed.2010,49, 9384-9387DOI: 10.1002/anie.201005363The (BOPA-R)FeCl2 complex was activated in the presence of Zn and exhibited catalytic activity for the hydrosilane reduction of ketones to give the S-configured alcohol. In contrast, the mixed-catalyst system of (BOPA-R)H and Fe(OAc)2 provides the R enantiomer. This approach provides both enantiomers from a single chiral source by the addition of a small amount of Zn.
A Chiral Iron Complex Containing a Bis(oxazolinyl)phenyl Ligand: Preparation and Asymmetric Hydrosilylation of Ketones
Hosokawa, S.; Ito, J.; Nishiyama, H.Organometallics2010,29, 5773-5775DOI: 10.1021/om1009186New chiral pincer iron complexes having bis(oxazolinyl)phenyl ligands have been synthesized by oxidative addition of Fe2(CO)9 to 2-bromo substituted ligands. This chiral pincer iron complex can catalyze asymmetric hydrosilylation of simple aromatic ketones to give the corresponding alcohols.
Asymmetric Direct Alkynylation Catalyzed by Chiral Ru-Bis(oxazolinyl)phenyl Complexes
Ito, J.; Asai, R.; Nishiyama, H.Org. Lett.2010,12, 3860-3862 [Link]Propargylic alcohols were obtained with excellent enantioselectivities in the asymmetric direct alkynylation of aldehydes using 5 mol% of chiral ruthenium complexes containing the chiral bis(oxazolinyl)phenyl ligand.
Chiral Bis(oxazolinyl)phenyl Ru(II) Catalysts for Highly Enantioselective Cyclopropanation
Ito, J.; Ujiie, S.; Nishiyama, H.Chem. Eur. J.2010,16, 4986-4990 [Link]Good to excellent enantioselectivities (up to 99% ee) of trans-cyclopropane derivatives were achieved in the cyclopropanation of alkenes with tert-butyl -diazoacetate by using 0.5mol% of a mononuclear chiral ruthenium aqua complex containing the chiral bis(oxazolinyl)phenyl ligand, which was obtained via CH activation by RuCl33H2O in the presence of Mg and cyclooctadiene (cod). Intramolecular cyclopropanation reactions using the new Ru complex also proceed with high yields and excellent enantioselectivities.
Iron- and Cobalt Catalyzed Asymmetric Hydrosilylation of Ketones and Enones with Bis(oxazolinylphenyl)amine Ligands
Inagaki, T.; Le, T. P.; Furuta, A.; Ito, J.; Nishiyama, H.Chem. Eur. J.2010,16, 3090-3096 [Link]Chiral bis(oxazolinylphenyl)amines proved to be efficient auxiliary ligands for iron and cobalt catalysts with high activity for asymmetric hydrosilylation of ketones and asymmetric conjugate hydrosilylation of enones.
Asymmetric β-boration of α,β-unsaturated carbonyl compounds promoted by chiral rhodium-bisoxazolinylphenyl catalysts
Shiomi, T.; Adachi, T.; Toribatake, K.; Zhou, L.; Nishiyama, H.Chem. Commun.2009, 5987-5989.[Link]Chiral rhodium?bisoxazolinylphenyl acetate complexes exhibited high catalytic activity for the β-boration of α,β-unsaturated carbonyl compounds with bis(pinacolato)diboron in the presence of sodium t-butoxide with enantioselectivity up to 97%.
Asymmetric Regioselective Direct Aldol Coupling of Enones and Aldehydes with Chiral Rh-Phebox Catalysts
Mizuno, M.; Inoue, H.; Naito, T.; Zhou, L.; Nishiyama, H.Chem. Eur. J.2009,15, 8985-8988.[Link]A chiral rhodium(bis-oxazolinyl) complex 1 exhibited catalytic activity for the asymmetric, regioselective direct coupling of cyclic enones and aldehydes (see scheme). The products were obtained with high anti selectivity up to 97 % and with up to 94 % ee.
Felkin-Anh selectivity in Rh(bisoxazolinylphenyl-catalyzed reductive aldol coupling reaction: asymmetric synthesis of stereotriads
Hashimoto. T.; Ito, J.; Nishiyama, H.Tetrahedron2008,64, 9408.The catalytic reductive aldol coupling of 2-phenylpropionaldehyde and acrylate derivatives with rhodium-bisoxazolinyl catalysts resulted in high Felkin-Anh selective and high enantiomeric excesses.
A new NCN pincer ruthenium complex and its catalytic activity for enantioselective hydrogenation of ketones
Ito, J.; Ujiie, S.; Nishiyama, H.Chem. Commun.2008, 1923-1925.[Link](Phebox-R)Ru(CO)(acac) complexes were synthesized by C-H bond activation with RuCl33H2O and were applied for enantioselecitve hydrogenation of ketones.
Highly Efficient Catalytic System for Hydrosilylation of Ketones with Iron(II) Acetate-Thiophenecarboxylate
Furuta, A.; Nishiyama, H.Tetrahedron Lett.2008,49, 110-113.A combination of a catalyst derived from ferrous acetate and sodium thiophene-2-carboxylate efficiently promoted hydrosilylation of aromatic and aliphatic ketones to give the corresponding secondary alcohols in high yields with extremely high selectivity.
Asymmetric Synthesis of a-chiral dihydrocinnamates by catalytic reductive aldol coupling and subsequent dehydroxylation
Hashimoto, T.; Shiomi, T.; Ito, J.; Nishiyama, H.Tetrahedron2007,63, 12883-12887.Optically active dihydrocinnamate derivatives bearing the chiral carbon center at α-position were synthesized by Rh(Phebox)-catalyzed asymmetric reductive aldol coupling reaction with substituted cinnamates and benzaldehyde derivatives and subsequent dehydroxylation reaction.
Cross-Coupling of Alkynes Catalyzed by Phebox-Rhodium Acetate Complexes
Ito, J.; Kitase, M.; Nishiyama, H.Organometallics2007,26, 6412-6417.[Link]Cross-coupling between terminal alkynes and dimethyl acetylenedicarboxylate (3) in the presence of 1 mol % bis(oxazolinyl)phenyl?rhodium acetate complex, (Phebox-R)Rh(OAc)2(H2O) (1-ip, R = iPr), under 1 atm hydrogen atmosphere furnished alkynyl-substituted maleic acid dimethyl esters with high Z-selectivity.
Diastereoselective reductive Mannich-type coupling of acrylates and aldimines with Rh(Phebox) catalyst
Nishiyama, H.;* Ishikawa, J.; Shiomi, T.Tetrahedron Lett.2007,48, 7841-7844.[Link]The conjugate reduction of α,β-unsaturated esters such as acrylates, crotonate, and cinnamates followed by Mannich-type coupling toward aldimines was efficiently promoted by rhodium-bis(oxazolinyl)phenyl catalyst and alkoxyhydrosilanes to show high anti-selectivity up to 99.
Intermolecular Asymmetric Reductive Aldol Reaction of Ketones as Acceptors Promoted by Chiral Rh(Phebox) Catalyst
Shiomi, T.; Nishiyama, H.Org. Lett.2007,9, 1651-1654.[Link]The conjugate reduction of cinnamates with hydrosilane and chiral Rh(Phebox-ip) catalyst in the presence of excess acetone is shown to provide the corresponding intermolecular reductive aldol product in extremely high enantioselectivity (up to 98%). Several cinnamates and crotonate substrates and several ketone acceptors were also examined.
Carbon-Hydrogen Bond Activation of Arenes by (Phebox)Rh(III)-Acetate Complex
Ito, J.; Nishiyama, H.Eur. J. Inorg. Chem.2007, 1114-1119.[Link]Thermolysis of the rhodium(III) complex [(dm-Phebox-dm)Rh(OAc)2(H2O)] [1; dm-Phebox-dm = 2,6-bis(4,4-dimethyloxazolinyl)phenyl] in various arenes results in the formation of the corresponding aryl complexes [(dm-Phebox-dm)Rh(Ar)(κ2-OAc)]. The relative rate of the reaction of 1 with monosubstituted benzenes C6H5X was determined to be: X = OMe (1.8) > COMe (1.6) > CF3 (1.2), Cl (1.2) > CH3 (1). The activation parameters: ΔH‡ = 22(2) kcal?mol?1, ΔS‡ = ?24(5) cal?mol?1?K?1 and kinetic isotope effect kH/kD = 5.4 were estimated.
An Iron-catalysed Hydrosilylation of Ketones
Nishiyama, H.; Furuta, A.Chem. Commun.2007, 760-762.[Link]The combination of Fe(OAc)2 and multi-nitrogen-based ligands such as N,N,N′,N′-tetramethyethylenediamine, bis-tert-butyl-bipyridine, or bis(oxazolinyl)pyridine can efficiently catalyse hydrosilylation of ketones to give the corresponding alcohols in high yields including asymmetric catalysis.
Conjugate Reduction of a,b-Unsaturated Aldehydes with Rhodium-(bisoxazolinylphenyl) Catalysts
Kanazawa, K.; Nishiyama. H.Synlett2006, 3343-3345.α,β-Unsaturated aldehydes were selectively reduced using rhodium(bisoxazolinylphenyl) complexes to give exclusive 1,4-selectivity in the combination of alkoxyhydrosilanes.
A Carbon-Carbon Bond Formation on Bis(oxazolinyl)phenyl-Rhodium Complex in Reduction and Oxidative Addition Sequence
Ito, J.; Miyakawa, T.; Nishiyama, H.Organometallics2006,25, 5216-5218.[Link]The unique C?C bond formation reaction between diisopropylamine and CH2Cl2 proceeding on a bis(oxazolinyl)phenyl rhodium complex (tBu-Phebox-dm)RhCl2(H2O) (1) was discovered. The intermediary chloromethyl complex, (tBu-Phebox-dm)Rh(CH2Cl)Cl(NEt3), which was obtained by reaction of 1 with CH2Cl2 in the presence of amine, underwent C?C bond formation with imine to give an azarhodacyclopentene complex, 2.
Efficient Preparation of New Rhodium- and Iridium-[bis(oxazolinyl)-3,5-dimethylphenyl] Complexes by C-H Bond Activation. An Application in Asymmetric Catalysis
Ito, J.; Shiomi, T.; Nishiyama, H.Adv. Synth. Catal.2006,348, 1235-1240.The bis(oxazolinyl)-3,5-dimethylphenylrhodium and -iridium complexes were synthesized in high yields by an efficient CH bond activation method with 4,6-dimethyl-1,3-bis(oxazolinyl)benzene derivatives. The catalytic activity of the complexes was examined for the asymmetric conjugate reduction of (E)-ethyl 3-phenylbut-2-enoate and the asymmetric reductive aldol reaction of tert-butyl acrylate and benzaldehyde. It was found that the rhodium complex of 3,5-dmPhebox showed the higher catalytic activity, whereas the corresponding iridium complexes proved to be less active.
Asymmetric Conjugate Reduction of α,β-Unsaturated Ketones and Esters with Chiral Rhodium(2,6-bisoxazolinylphenyl) Catalysts
Kanazawa, Y; Tsuchiya, Y.; Kobayashi, K.; Shiomi, T.; Itoh, J.-I.; Kikuchi, M.; Yamamoto, Y.; Nishiyama, H.Chem. Eur. J.2006,12, 63-71.[Link]New asymmetric conjugate reduction of β,β-disubstituted ,β-unsaturated ketones and esters was accomplished with alkoxylhydrosilanes in the presence of chiral rhodium(2,6-bisoxazolinylphenyl) complexes in high yields and high enantioselectivity. (E)-4-Phenyl-3-penten-2-one and (E)-4-phenyl-4-isopropyl-3-penten-2-one were readily reduced at 60?°C in 95?% ee and 98?% ee, respectively, by 1 mol?% of catalyst loading. (EtO)2MeSiH proved to be the best hydrogen donor of choice. tert-Butyl (E)-β-methylcinnamate and β-isopropylcinnamate could also be reduced to the corresponding dihydrocinnamate derivatives up to 98% ee.
High performance of Rh(Phebox) catalysts in asymmetric reductive aldol reaction: High anti-selectivity
Nishiyama, H.; Shiomi, T.; Tsuchiya, Y.; Matsuda, I.J. Am. Chem. Soc.2005,127, 6972-6973.[Link]Chiral rhodium(bisoxazolinylphenyl) complexes (1 mol %) efficiently catalyze the asymmetric reductive aldol reaction of aldehydes and α,β-unsaturated esters at 50 °C for ca. 0.5?1.0 h with several hydrosilanes to give the corresponding β-hydroxypropionates with extremely high anti-selectivity (up to 98%) and enantioselectivity (up to 96% ee). The stereochemical outcome is likely due to a chairlike cyclic transition state involving rhodium-(E)-enolate.