The First General, Efficient and Highly Enantioselective Reduction of Quinoxalines and Quinoxalinones

Rueping, Magnus; Tato, Francisco; Schoepke, Fenja R.

doi:10.1002/chem.200902907

Cited by 192 publications

(53 citation statements)

References 96 publications

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“…Having established a protocol for a general and highly enantioselective transfer hydrogenation of quinolines, we decided to extend its scope to the reduction of quinoxalines 7 (Table 5) [107]. The asymmetric reduction of quinoxalines is typically more difficult to achieve.…”

Section: Resultsmentioning

confidence: 99%

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

Rueping¹,

Bootwicha²,

Sugiono³

2012

Beilstein J. Org. Chem.

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SummaryThe asymmetric organocatalytic hydrogenation of benzoxazines, quinolines, quinoxalines and 3H-indoles in continuous-flow microreactors has been developed. Reaction monitoring was achieved by using an inline ReactIR flow cell, which allows fast and convenient optimization of reaction parameters. The reductions proceeded well, and the desired products were isolated in high yields and with excellent enantioselectivities.

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Section: Resultsmentioning

confidence: 99%

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

Rueping¹,

Bootwicha²,

Sugiono³

2012

Beilstein J. Org. Chem.

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“…HEH 2a and 10 mol.% of the Brønsted acid 5c at 35 • C in chloroform [47]. Remarkably, a broad range of substrates, with different substitution patterns on both aryl and tetrahydroquinoxaline cores, is tolerated in the reaction (Figure 22.19c, 31a-f).…”

Section: Asymmetric Brønsted Acid Catalyzed Hydrogenation Of Benzoxazmentioning

confidence: 92%

Bio‐Inspired Transfer Hydrogenations

Rueping

Schoepke

Atodiresei

et al. 2011

Biomimetic Organic Synthesis

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IntroductionThe demand for chiral molecules, particularly those with hydrogen as part of the stereogenic center, has increased in recent years, and intensive research has been carried out in both industry and academia to develop efficient methods for synthesizing such compounds [1]. In this context, significant attention has been devoted to the asymmetric hydrogenation of unsaturated compounds, for example, olefins, carbonyls, and imines, which is recognized as one of the most important and convenient routes to the corresponding optically active products [2]. So far, most of the enantioselective reductions rely on biological processes or transition metal catalyzed high-pressure hydrogenations, hydrosilylations, and transfer hydrogenations. Beside their high substrate specificity, the enzymatic processes sometimes suffer from undesired by-products, poor catalyst stability under the operational conditions, substrate and/or product inhibition, and problems with catalyst recovery. Likewise, despite the high reactivity and selectivity exhibited by the organometallic complexes employed in the metal-catalyzed processes, most of these protocols suffer from a limited number of substrates and difficulties with catalyst separation and recycling. Hence, an alternative approach to these chiral compounds would be of great value. Nature's Reductions: Dehydrogenases as a Role ModelEnzymes are catalysts that evolve in Nature and one of their characteristics is high selectivity. During biochemical transformations, enzymes are assisted by non-proteinogenic molecules called co-factors. For instance, nicotinamide adenine dinucleotide (NADH), one of the essential co-factors in Nature, serves as a hydride source for various biological reductions. The synthesis of the amino acid glutamate by the glutamate dehydrogenase (GDH) catalyzed reductive amination of 2-ketoglutarate represents one example (Equation 22.1). The reaction is reversible Biomimetic Organic Synthesis, First Edition. Edited by Erwan Poupon and Bastien Nay.

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“…[36][37][38][39][43][44] The regioselectivity for 4-substituted 1,2-diaminobenzenes on treatment with phenylglyoxal in the presence of SnCl 2 /SiO 2 was also investigated (Table 5, entries [17][18][19][20]. With the exception of 2,3-diaminopyridine, which showed very high selectivity to cis-regioisomer 1t, [45][46] the condensation of other 4-substituted 1,2-diaminobenzenes with phenylglyoxal resulted in a mixture of regioisomers 1q-1s, in favor of trans-regioisomers [47][48][49] ( Fig. 3).…”

Section: Study On Homogeneous Common Lewis Acids As Potentialmentioning

confidence: 99%

Heterogeneous SnCl₂/SiO₂versus Homogeneous SnCl₂Acid Catalysis in the Benzo[N,N]-heterocyclic Condensation

Darabi¹,

Aghapoor²,

Mohsenzadeh³

et al. 2011

Bulletin of the Korean Chemical Society

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The First General, Efficient and Highly Enantioselective Reduction of Quinoxalines and Quinoxalinones

Cited by 192 publications

References 96 publications

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

Bio‐Inspired Transfer Hydrogenations

Heterogeneous SnCl₂/SiO₂versus Homogeneous SnCl₂Acid Catalysis in the Benzo[N,N]-heterocyclic Condensation

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The First General, Efficient and Highly Enantioselective Reduction of Quinoxalines and Quinoxalinones

Cited by 192 publications

References 96 publications

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

Bio‐Inspired Transfer Hydrogenations

Heterogeneous SnCl2/SiO2versus Homogeneous SnCl2Acid Catalysis in the Benzo[N,N]-heterocyclic Condensation

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Heterogeneous SnCl₂/SiO₂versus Homogeneous SnCl₂Acid Catalysis in the Benzo[N,N]-heterocyclic Condensation