Sequential ruthenium(II) catalyzed reactions for the production of secondary amines from simple imines are reported. They involve Ru(II)-acetate based catalytic systems for C–H Bond ...activation/diarylation of simple imines with aryl bromides followed by RuCl2(arene)2 hydrosilylation of diarylated imines. The direct diarylation of aldimines can be profitably produced by Ru(II) catalytic systems in the presence of both acetate and PPh3 ligands. By contrast, PPh3 additive disfavors diarylation of ketimines that is achieved with Ru(OAc)2(p-cymene) alone. The catalytic hydrosilylation of the resulting imines was simply performed with H2SiPh2 in the presence of RuCl2(arene)2 catalyst at room temperature leading to overall yield of 70–86% of secondary amines
Ruthenium(II)-acetate catalysts are shown to promote sp
2
C–H bond activation/diarylation of arylimines with aryl bromides selectively at
ortho
positions in both organic solvent (
N
...-methylpyrrolidone, NMP) and in water. Water allows to produce a more active ruthenium catalyst for diarylation of ketimines. Furthermore, the diarylation of imines in water in basic media allows the access to diarylated aldehyde. Sequential catalytic C–H arylation/reduction using either a stoichiometric amount of NaBH
3
CN or via a ruthenium(II) catalytic hydrosilylation of the resulting imines offers a direct route to bulky secondary amines.
The catalytic activity in asymmetric transfer hydrogenation of ketones using octahedral and half-sandwich (η
5-indenyl and η
6-arene) ruthenium(II) complexes containing the chiral ligand (4
S)-2-(
S
...p
)-2-(diphenylphosphino)ferrocenyl-4-(isopropyl)oxazoline (FcPN) has been explored. Catalytic studies with complex
fac-RuCl
2{η
2(
P,
N)-FcPN}(PMe
3)
2 (
1) show excellent TOF values (9600
h
−1). Experiments in the presence of free FcPN, which lead to an increase in conversion rates and ee values when the catalyst is complex Ru(η
5-C
9H
7){κ
2(
P,
N)-FcPN}(PPh
3)PF
6 (
4) have been carried out. The characterization of the new complexes
mer–
trans-RuCl
2{P(OMe)
3}
2{κ
2(
P,
N)-FcPN} and of the water-soluble complexes
fac- and
mer–
trans-RuCl
2(PTA)
2{κ
2(
P,
N)-FcPN} is also reported.
The catalytic activity in asymmetric transfer hydrogenation of ketones using octahedral and half-sandwich (η
5-indenyl and η
6-arene) ruthenium(II) complexes containing the chiral ligand (4
S)-2-(
S
p
)-2-(diphenylphosphino)ferrocenyl-4-(isopropyl)oxazoline (FcPN) has been explored. Catalytic studies with complex
fac-RuCl
2{η
2(
P,
N)-FcPN}(PMe
3)
2 (
1) show excellent TOF values (9600
h
−1). Experiments in the presence of free FcPN, which lead to an increase in conversion rates and ee values when the catalyst is complex Ru(η
5-C
9H
7){κ
2(
P,
N)-FcPN}(PPh
3)PF
6 (
4) have been carried out. The characterization of the new complexes
mer–
trans-RuCl
2{P(OMe)
3}
2{κ
2(
P,
N)-FcPN} and of the water-soluble complexes
fac- and
mer–
trans-RuCl
2(PTA)
2{κ
2(
P,
N)-FcPN} is also reported.
Graphic
New practical conditions of asymmetric hydrogenation of β-keto esters with chiral Ru(II) catalysts are described. It is now possible to carry out the reaction at
atmospheric pressure. Under ...these conditions, β-keto esters are hydrogenated to β-hydroxy esters with excellent enantiomeric excesses (up to 99%) using chiral ruthenium (II) catalysts easily prepared
in situ by treatment of commercially available (COD)Ru(2-methylallyl)
2 in the presence of the appropriate chiral ligands such as Binap, MeO-Biphep and Me-Duphos.
Graphic
2-chloro-3-keto esters were quantitatively hydrogenated to
syn and
anti 2-chloro-3-hydroxyester by asymmetric hydrogenation with chiral ruthenium (II) catalysis prepared
in-situ from ...(COD)Ru(2-Methylallyl)
2 in presence of atropisomeric ligands such as MeO-Biphep and Binap, giving enantioselectivity up to 99%. 2-chloro-3-hydroxy esters were treated with different bases to give (E)- and (Z)-2,3-epoxyalkanoates in 65–90% yields with 84–97% ee.
A tandem approach to synthesize symmetrical azines from alcohols and hydrazine hydrate catalyzed by new Ru(II) hydrazone complex was reported. A diverse range of azines was synthesized in good yields ...using 1 mol % of catalyst. Remarkably, the catalytic reactions operate under aerobic and mild reaction conditions with the release of water as the by product.
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•Synthesize of azines from alcohols and hydrazine hydrate catalyzed by Ru(II) hydrazone complexes was reported.•A diverse range of azines was synthesized in good to high yields using 1 mol % of catalyst loading.•The catalytic reactions operate under aerobic condition with the release of water as the by product.
New ruthenium(II) complexes (1–4) were synthesized from the reaction of ligands namely 10-(2-(benzothiazol-2-yl)hydrazano)phenanthren-9(10H)-one (BTPQ) or 10-(2-(quinolin-2-yl)hydrazano)phenanthren-9(10H)-one (QHPQ) with RuHCl(CO)(EPh3)3 (E = P or As) under reflux. The formation of the complexes was confirmed by analytical and various spectral methods including single crystal XRD analysis. The synthesized complexes were applied as catalysts for the synthesis of symmetrical azines from alcohols and hydrazine hydrate under air. Different substituents in alcohols were well tolerated and wide spectrum of azines were synthesized in good to excellent yields using 1 mol % of catalyst loading. The aerobic catalytic reaction releases environmentally benign H2O is the only byproduct. Moreover, a plausible mechanism has been provided for the Ru-catalyzed azine synthesis.
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•Ruthenium(II) complexes with hydrazone ligands were designed and synthesized.•Ruthenium(II) complexes were successfully applied ascatalysts in α-alkylation reactions.•Ruthenium ...catalyzed α-alkylations undergo via environmentally friendly borrowing hydrogen pathway.
As a immersion for development of new complexes, new Ru(II) complexes (1–3) supported by benzothiazole hydrazine Schiff bases of the type Ru(SAL-HBT)(CO)(AsPh3)2, Ru(VAN-HBT)(CO)(AsPh3)2 and Ru(NAP-HBT)(CO)Cl(AsPh3)2 SAL-HBT = (salicyl((2-(benzothiazol-2yl)hydrazono)methylphenol)), VAN-HBT = 2-((2-(benzothiazol-2-yl)hydrazono)methyl)-6 methoxyphenol) and NAP-HBT = naphtyl-2-((2-(benzothiazol-2-yl)hydrazono)methyl phenol) were synthesized. Their identities have been established by satisfactory elemental analyses, various spectroscopic techniques (IR, (1H, 13C) NMR) and also mass spectrometry. The ruthenium(II) ion exhibits a hexa coordination with distorted octahedral geometry. In complexes 1 and 2, the ligand coordinated as dianionic tridentate fashion by forming N^N donor five member and N^O donor six member chelate rings. However, in complex 3, the ligand coordinated as monoanionic bidentate fashion by forming N^N donor five-membered ring. The new ruthenium(II) carbonyl complexes were successfully applied as catalysts in α -alkylation of aliphatic and aromatic ketones with alcohols via borrowing hydrogen strategy. Various parameters such as base, solvent, temperature, time and catalyst loading on the catalytic activity were analyzed. From the results, the catalyst 1 was found to be the best catalyst for α-alkylation reaction to obtain excellent yield. The catalytic system has a broad substrate scope, which allows the synthesis of α-alkylated ketones in mild reaction conditions with low catalyst loading under air atmosphere.
Heterocyclic compounds containing pyrrole and indole-fused isocoumarins were obtained from a one-pot synthesis
via
annulations of N-heterocyclic carboxylic acids and alkynes with N
∧
O chelate ...ruthenium(II) complex, RuCl(
PySO
3
)
(
p
-cymene) (
PySO
3
= 2-pyridinesulfonate) in the presence of Cu(OAc)
2
H
2
O. The reaction proceeds efficiently in DMF but can also be performed in other solvents such as dichloroethane,
t
AmOH, and water. The annulations reaction is regioselective when performed 1-methylpyrrole-2-carboxylic acid with 1-phenyl-1-propyne.
GRAPHICAL ABSTRACT
Pyrrole and indole-fused isocoumarins are obtained from a one-pot synthesis via annulations of heterocyclic acids and alkynes with N
∧
O chelate ruthenium(II) complex, RuCl(
PySO
3
)
(
p
-cymene)(
PySO
3
= 2-pyridinesulfonate) in the presence of Cu(OAc)
2
H
2
O. The annulation reaction is regioselectively performed with 1-methylpyrrole-2-carboxylic acid and 1-phenyl-1-propyne in DMF.
Ruthenium complexes of the type Cp∗Ru(PPh3)(PR3)Cl (PR3=PTA, PPh3, or PMe3) efficiently catalyzed the atom transfer radical addition of chlorinated esters across styrene and that of carbon ...tetrachloride across a variety of olefins, affording the adducts in good to excellent yields at 60–85°C. Display omitted
► Cp′Ru(PPh3)(PR3)Cl catalyzed atom transfer radical addition (ATRA). ► Highly active catalysts for ATRA. ► Addition of CCl4 and chlorinated esters to olefins. ► Addition of CCl4 to stilbene and chalcone.
Cp∗Ru(PPh3)(PR3)Cl complexes, where PR3=PMe3, PPh3, or PTA (PTA=1,3,5-triaza-7-phosphaadamantane), were used to catalyze the atom transfer radical addition of chlorinated esters (CCl3CO2Et, CH2ClCO2Et) to styrene, and that of CCl4 to a variety of olefins. The monoadducts were obtained in moderate to excellent yields. Moreover, high selectivities were obtained for the addition of CCl4 to internal olefins. The activity of Cp∗Ru(PTA)(PPh3)Cl and Cp∗Ru(PTA)(PMe3)Cl were comparable to that of the highly efficient ATRA catalyst, Cp∗Ru(PPh3)2Cl. The addition of CCl3CO2Et to styrene catalyzed by Cp′Ru(PPh3)(PR3)Cl (Cp′=Dp, Ind, Cp, Tp) are also reported here. Two new compounds, 3-chloro-3-phenyl-2-(trichloromethyl)-1-phenylpropan-1-one and 1,3,3,3-tetrachloro-1,2-diphenylpropane, resulting from the addition of CCl4 to chalcone and cis-stilbene have been isolated and characterized by NMR spectroscopy and X-ray crystallography.
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