One-pot asymmetric synthesis of tert-butanesulfinyl-protected amines from ketones by the in situ reduction of tert-butanesulfinyl ketimines

Borg, George; Cogan, Derek A.; Ellman, Jonathan A.

doi:10.1016/s0040-4039(99)01351-9

Cited by 112 publications

(94 citation statements)

References 11 publications

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“…[21][22][23] A recent report has shown that 12 can be produced as a mixture with other phenolic monomers through bimetallic hydrogenolysis of organosolv lignin in water.…”

Section: Technologiestoproducechemicalsandfuelsfromrenewablementioning

confidence: 99%

Isolation of Functionalized Phenolic Monomers through Selective Oxidation and CO Bond Cleavage of the β‐O‐4 Linkages in Lignin

et al. 2014

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Functionalized phenolic monomers have been generated and isolated from an organosolv lignin through a two-step depolymerization process. Chemoselective catalytic oxidation of b-O-4 linkages promoted by the DDQ/tBuONO/ O 2 system was achieved in model compounds, including polymeric models and in real lignin. The oxidized b-O-4 linkages were then cleaved on reaction with zinc. Compared to many existing methods, this protocol, which can be achieved in one pot, is highly selective, giving rise to a simple mixture of products that can be readily purified to give pure compounds. The functionality present in these products makes them potentially valuable building blocks.

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“…[21][22][23] A recent report has shown that 12 can be produced as a mixture with other phenolic monomers through bimetallic hydrogenolysis of organosolv lignin in water.…”

Section: Technologiestoproducechemicalsandfuelsfromrenewablementioning

confidence: 99%

Isolation of Functionalized Phenolic Monomers through Selective Oxidation and CO Bond Cleavage of the β‐O‐4 Linkages in Lignin

et al. 2014

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“…The organic layer was successively washed with 85 Ellman and co-workers in 1999 reported on a one-pot method for the asymmetric synthesis of previously protected a-substituted amines by the Ti(OEt) 4 -mediated NaBH 4 reduction of N-tert-butanesulfinyl ketimines. 134 The corresponding ketones and N-tert-butane sulfinamide generated the imines 135 in situ. A rigorous optimization revealed NaBH 4 as the best reductant in this case, and Ti(OEt) 4 was used for several purposes like as a water scavenger, as a catalyst for imine condensation, and as a Lewis acid to provide an enhanced reaction rate and diastereomeric ratio.…”

Section: Diastereoselective Reductive Amination Using Chiral Auxiliariesmentioning

confidence: 99%

Asymmetric Hydroamination and Reductive Amination in Total Synthesis

Ghorai

Tiwari

Bhattacharyya

2013

Stereoselective Synthesis of Drugs and Natural Products

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Asymmetric hydroamination (AHA) and asymmetric reductive amination (ARA) are one of the most popular strategies for enantioselective synthesis of chiral amines, which are very important from a synthetic and a biological point of view. The addition of the NH bond across an unsaturated CC bond is known as hydroamination. AHA is ideal for industrial processes as it is a 100% atom‐economic reaction and involves readily available substrates. For broadening its scope for a variety of substrates, many metal‐based as well as metal‐free catalytic systems have been developed for asymmetric hydroamination. Along with the synthesis of functionalized chiral amines, AHA has served as a key strategy in the synthesis of the core of various natural products like codeine, pseudodistomin, swainsonine and of drugs like pentazocine. Reductive amination is a widely used efficient synthetic protocol to install an amine group in place of a carbonyl group in an organic compound. The reaction proceeds through the formation of imine and subsequent one‐pot reduction of it to give the product amine. Use of a metal‐chiral ligand combination, chiral Brønsted acid or chiral organocatalyst, or chiral auxiliary in the reaction can give rise to chiral amine products that are often valuable synthetic intermediates en route to many drugs and natural products. Application of these protocols in the total synthesis of drugs and natural products will be discussed along with some experimental procedures.

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“…In 1999, the group of Ellman demonstrated a two-stage, no workup ketone to amine synthesis [36]. This was achieved by adding the (S)-or (R)-tert-butylsulfinamide auxiliary, [t-BuS(O)NH 2 ], limiting reagent, to the ketone (1.2 equiv) and Ti(OEt) 4 240j 7 Asymmetric Reductive Amination (TLC examination) is cooled to À48 C and then transferred via cannula to a À48 C THF suspension of NaBH 4 (4 equiv).…”

Section: 43mentioning

confidence: 99%

Asymmetric Reductive Amination

Nugent

2010

Chiral Amine Synthesis

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Despite its long history and common usage of the term, reductive amination has remained underdeveloped. Many studies are available regarding racemic reductive amination, but only B€ orner and Tararov have provided summaries of the asymmetric version [1]. In this chapter we provide an overview of the available methods and achievements since the first demonstrated enantioselective reductive amination by Blaser in 1999 [2].Compared to the large volume of reports detailing asymmetric imine reduction, only a small number of publications are available regarding asymmetric reductive amination. Reductive amination remains less developed than the field of imine reduction due in great part to the incompatibility of transition metal hydride catalysts in the presence of ketones (alcohol by-product formation) and/or catalyst inhibition arising from amine starting material or amine product complexation with a catalytically active transition metal species [3]. Future method development will surely require striking the right balance between these competing nonproductive reaction pathways.Before discussing the relevant literature, a few qualifiers are mentioned and discussed. Reductive amination is sometimes incorrectly associated with the reduction of preformed imines and derivatives thereof. Reductive amination, by definition, is only the one-pot conversion of a ketone to an amine in which a reductant coexists in the presence of a ketone starting material [4]. The term indirect reductive amination is occasionally used, but can be more tersely and accurately described as imine reduction [5]. The reader will note that depending on the perspective one takes for the transformation, the term reductive amination is applied when considering the reaction course of the ketone starting material, and the term reductive alkylation is applied when describing the starting amines conversion to the product amine.Included in this section are procedures that are not classified as reductive amination, but are also not imine reductions in the sense that an imine has been isolated, here isolation means a work-up or distillation has been performed before the

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One-pot asymmetric synthesis of tert-butanesulfinyl-protected amines from ketones by the in situ reduction of tert-butanesulfinyl ketimines

Cited by 112 publications

References 11 publications

Isolation of Functionalized Phenolic Monomers through Selective Oxidation and CO Bond Cleavage of the β‐O‐4 Linkages in Lignin

Isolation of Functionalized Phenolic Monomers through Selective Oxidation and CO Bond Cleavage of the β‐O‐4 Linkages in Lignin

Asymmetric Hydroamination and Reductive Amination in Total Synthesis

Asymmetric Reductive Amination

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