Enantioselective Transfer Hydrogenation of Oxocarbenium Ions Enables Asymmetric Access to α-Substituted 1,3-Dihydroisobenzofurans

Synthesis ◽  
2021 ◽  
Author(s):  
Lei Liu ◽  
Likai Zhou ◽  
Kuiyong Jia ◽  
xigong Liu
Keyword(s):  
Enantioselective Hydrogenation ◽  
Transfer Hydrogenation ◽  
Oxocarbenium Ions ◽  
High Yields

Reported here is an efficient enantioselective hydrogenation of cyclic oxocarbenium ions generated in situ through collapse of corresponding acetal substrates. The asymmetric approach provides a straightforward access to a variety of chiral α-aryl substituted 1,3-dihydroisobenzofurans in high yields with excellent enantioselectivities.α-Alkynyl substituted 1,3-dihydroisobenzofurans were also proved to be suitable substrates. In addition, when the reaction was performed at gram scale, the desired product was obtained in good yields with excellent enantioselectivity.

Hypervalent iodine catalysis for selective oxidation of Baylis–Hillman adducts via in situ generation of o-iodoxybenzoic acid (IBX) from 2-iodosobenzoic acid (IBA) in the presence of oxone

2016 ◽  
Vol 40 (12) ◽  
pp. 10300-10304 ◽  
Author(s):  
Raktani Bikshapathi ◽  
Parvathaneni Sai Prathima ◽  
Vaidya Jayathirtha Rao
Keyword(s):  
Selective Oxidation ◽  
Carbonyl Compounds ◽  
Hypervalent Iodine ◽  
In Situ Generation ◽  
Iodosobenzoic Acid ◽  
High Yields

An efficient, eco-friendly protocol for selective oxidation of primary and secondary Baylis–Hillman alcohols to the corresponding carbonyl compounds in high yields has been developed with 2-iodosobenzoic acid (IBA).

Asymmetrische Katalysen, 25 [1]. C5H5Mn(CO)2-Komplexe von optisch aktiven Chelatphosphanen als einzähnige Liganden in der enantioselektiven Katalyse / Asymmetric Catalyses, 25 [1]. C5H5Mn(CO)2 Complexes of Optically Active Chelate Phosphanes as Monodentate Ligands in Enantioselective Catalysis

1985 ◽  
Vol 40 (10) ◽  
pp. 1243-1249 ◽  
Author(s):  
Henri Brunner ◽  
Alfons Knott
Keyword(s):  
Cinnamic Acid ◽  
Enantioselective Hydrogenation ◽  
Optically Active ◽  
Enantioselective Catalysis ◽  
Dinuclear Complexes ◽  
Bidentate Ligands ◽  
Monodentate Ligand ◽  
Mononuclear Complexes ◽  
Monodentate Ligands

The chelate phosphanes Diphos, Diop, and Norphos were reacted with C5H5Mn(CO)2THF and CH3C5H4Mn(CO)2THF to give mononuclear complexes, containing the phosphanes as unidentate or as bidentate ligands, and dinuclear complexes, containing bridging phosphane ligands. In C5H5Mn(CO)2Diop one of the two P(C6H5)2 groups of Diop is coordinated to the C5H5Mn(CO)2 fragment; the uncoordinated P(C6H5)2 group makes it a monodentate ligand. C5H5Mn(CO)2Diop together with [Rh(cod)Cl]2 was used as an in situ catalyst in the enantioselective hydrogenation of (Z)-a-[N -acetam ino]cinnamic acid (78.4% ee) and in the enantioselective hydrosilylation of acetophenone with diphenylsilane (6.7% ee).

In Situ Generation of Diimide from Hydrazine and Oxygen: Continuous-Flow Transfer Hydrogenation of Olefins

2013 ◽  
Vol 125 (39) ◽  
pp. 10431-10434 ◽  
Author(s):  
Bartholomäus Pieber ◽  
Sabrina Teixeira Martinez ◽  
David Cantillo ◽  
C. Oliver Kappe
Keyword(s):  
Continuous Flow ◽  
Transfer Hydrogenation ◽  
In Situ Generation ◽  
Flow Transfer

The Acceleration of the Rearrangement of α-Hydroxy Aldimines by Lewis or Brønsted Acids

Synlett ◽  
2018 ◽  
Vol 29 (15) ◽  
pp. 2015-2018 ◽  
Author(s):  
William Wulff ◽  
Xin Zhang ◽  
Yijing Dai
Keyword(s):  
Silica Gel ◽  
Efficient Method ◽  
Bronsted Acids ◽  
High Yields

An efficient method was developed for the synthesis of α-amino ketones from α-hydroxy imines. The reaction occurs through an α-iminol rearrangement involving the migration of a substituent of the carbinol carbon to the imine carbon. The optimal catalysts were found to be silica gel or montmorillonite K 10, which effected migration of a variety of aryl and alkyl substituents in high yields. The rearrangement can also be carried out on imines generated in situ from aldehydes and amines in essentially the same yields as those from the preformed imines.

Geological and Gas-Content Features of Coalbed Methane System in Qinshui Basin, Shanxi

2012 ◽  
Vol 170-173 ◽  
pp. 1187-1191
Author(s):  
Ya Hui Jia ◽  
Xiao Ping Xie ◽  
Ai Li Lu
Keyword(s):  
Coalbed Methane ◽  
Gas Content ◽  
Structural Deformation ◽  
Shanxi Province ◽  
Qinshui Basin ◽  
The North ◽  
North Part ◽  
Coalbed Methane Reservoir ◽  
High Yields

Colabed methane system is a natural system that consists of coal seams, coalbed methane in them and surrounding rocks. As an unconventional natural gas, reservoir and conservation of coalbed methane are different from those of conventional hydrocarbon. The Qinshui Basin, covering an area about 30,000sq.km in southeastern Shanxi Province, has abundant coalbed methane resources in the carboniferous Taiyuan formation and permian Shanxi formation, with an in-situ methane resource 3.3×1012 m3.In this study, the structural deformation and tectonic evolution of coalbed methane system in Qinshui basin were reported. Relationships between structural deformation and the formation of coalbed methane reservoir in Qinshui Basin were also discussed. The results show that Yangquan-Shouyang area in the north part of the basin and Tunliu-Xiangyuan area in the east are favorable for formation coalbed methane system. In contrast, Jincheng-Qinshui area in the south part of basin and the Qinyuan area in the middle of basin are favorable for both the formation of coalbed methane reservoirs and high yields as well.

Selective Zincation of 1,2-Dicyanobenzene and Related Benzonitriles in Continuous Flow Using In Situ Trapping Metalations

Synlett ◽  
2017 ◽  
Vol 28 (20) ◽  
pp. 2817-2822 ◽  
Author(s):  
Marthe Ketels ◽  
Dorothée Ziegler ◽  
Paul Knochel
Keyword(s):  
Continuous Flow ◽  
Metal Salt ◽  
Aromatic Substrate ◽  
Metallic Salt ◽  
High Yields

A mild and general metalation procedure for the functionalization of 1,2-dicyanobenzene and related polyfunctionalized benzonitriles using a commercially available continuous flow setup is reported. The addition of TMPLi (TMP = 2,2,6,6-tetramethylpiperidyl) to a mixture of an aromatic substrate with a metallic salt such as ZnCl2 under appropriate conditions (0 °C, 20 s) leads to fast in situ lithiation of the arene followed by transmetalation with ZnCl2 to afford the corresponding functionalized arylzinc compound that were trapped with various electrophiles in high yields. The reaction scope of these in situ trapping metalations in flow is broader and needs less equivalents of the base and the metal salt than the corresponding batch procedure.

scholarly journals The first in situ synthesis of 1,3-dioxan-5-one derivatives and their direct use in Claisen-Schmidt reactions

2019 ◽  
Vol 25 (1) ◽  
pp. 85-90 ◽  
Author(s):  
M. Javad Poursharifi ◽  
Mohammad M. Mojtahedi ◽  
M. Saeed Abaee ◽  
Mohammad M. Hashemi
Keyword(s):  
Acetic Acid ◽  
Aromatic Aldehydes ◽  
In Situ Synthesis ◽  
Stepwise Procedures ◽  
Time Periods ◽  
High Yields ◽  
Short Time ◽  
Direct Use ◽  
Derivatives Of

AbstractA method is developed for in situ generation of 1,3-dioxan-5-one derivatives 2. These compounds are simple precursors for accessing carbohydrate structures and previously had to be produced via stepwise procedures using excessive amounts of reagents. In the present work, three different derivatives of 2 were synthesized via the reaction of trialkoxyalkanes with dihydroxyacetone dimer 1 in the presence of acetic acid as the catalyst. In the same pot, derivatives of 2 were reacted with aromatic aldehydes and 30 mol% of pyrrolidine to obtain high yields of the respective bischalcones 3 within short time periods.

scholarly journals A facile and highly efficient transfer hydrogenation of ketones and aldehydes catalyzed by palladium nanoparticles supported on mesoporous graphitic carbon nitride

2019 ◽  
Vol 44 (1-2) ◽  
pp. 14-19
Author(s):  
Bilal Nişancı ◽  
Ziya Dağalan
Keyword(s):  
Carbon Nitride ◽  
Glass Tube ◽  
Pd Nanoparticles ◽  
Graphitic Carbon ◽  
Transfer Hydrogenation ◽  
Graphitic Carbon Nitride ◽  
Reusable Catalyst ◽  
Hydrogenation Reactions ◽  
High Yields ◽  
Benzaldehyde Derivatives

A novel transfer hydrogenation methodology for the reduction of ketones (14 examples) and benzaldehyde derivatives (12 examples) to the corresponding alcohols using Pd nanoparticles supported on mesoporous graphitic carbon nitride (mpg-C3N4/Pd) as a reusable catalyst and ammonia borane as a safe hydrogen source in an aqueous solution MeOH/H2O (v/v = 1/1) is described. The catalytic hydrogenation reactions were conducted in a commercially available high-pressure glass tube at room temperature, and the corresponding alcohols were obtained in high yields in 2–5 min. Moreover, the presented transfer hydrogenation protocol shows partial halogen selectivity with bromo-, fluoro-, and chloro-substituted carbonyl analogs. In addition, the present catalyst can be reused up to five times without losing its efficiency, and scaling-up the reaction enables α-methylbenzyl alcohol to be produced in 90% isolated yield.

scholarly journals Highly Asymmetric Reduction of New Benzofuryl and Benzothiophenyl α-Amino Ketones

Proceedings ◽  
2019 ◽  
Vol 41 (1) ◽  
pp. 49
Author(s):  
Agnieszka Tafelska-Kaczmarek ◽  
Marcin Kwit ◽  
Bartosz Stasiak
Keyword(s):  
High Performance ◽  
Asymmetric Reduction ◽  
Theoretical Calculations ◽  
Transfer Hydrogenation ◽  
Central Position ◽  
Chiral Hplc ◽  
Naturally Occurring ◽  
Approved Drugs ◽  
High Yields ◽  
Derivatives Of

Heterocyclic compounds play an important role in medicinal chemistry and occupy a central position in synthetic organic chemistry. Both benzofuran and benzothiophene are considered as very important structures due to their diverse biological and pharmacological profile. Many clinically approved drugs are synthetic and naturally occurring substituted benzofuryl and benzothiophenyl derivatives in conjunction with other heterocycles. Therefore, a new series of α-amino ketone (containing various azole rings) derivatives of benzofuran and benzothiophene are synthesized and subjected to the transfer hydrogenation with formic acid, catalyzed by RhCl[(R,R)-TsDPEN](C5Me5). The corresponding optically active β-amino alcohols are obtained in high yields and excellent enantioselectivities (93%–99%), as determined by chiral HPLC (high-performance liquid chromatography). The absolute configuration of the products is confirmed by means of ECD (electronic circular dichroism) spectroscopy, supported by theoretical calculations.

Highly Selective One-Pot Synthesis of Polysubstituted Isoflavanes using Styryl Ethers and Electron-Withdrawing ortho-Quinone Methides Generated In Situ

Synlett ◽  
2018 ◽  
Vol 30 (02) ◽  
pp. 189-192 ◽  
Author(s):  
Yujiro Hoshino ◽  
Kiyoshi Honda ◽  
Kenta Tanaka ◽  
Mami Kishimoto ◽  
Naoya Ohtsuka ◽  
...  
Keyword(s):  
Biologically Active ◽  
Quinone Methides ◽  
One Pot ◽  
One Pot Synthesis ◽  
Reaction Proceeds ◽  
Acidic Conditions ◽  
High Yields

A highly selective one-pot synthesis of polysubstituted isoflavanes has been developed. The reaction proceeds through the cycloaddition of methyl styryl ethers, derived from phenylacetaldehyde dimethyl acetals under acidic conditions, with electron-withdrawing ortho-quinone methides generated in situ. When phenylacetaldehyde dimethyl acetals were reacted with salicylaldehydes, the reaction proceeded smoothly to afford the corresponding isoflavanes stereoselectively in high yields and with excellent regioselectivities. The present reaction provides versatile access to functionalized isoflavanes, and constitutes a useful tool for the synthesis of biologically active molecules.

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