Reductive deoxygenation of esters with trichlorosilane

Baldwin, S. W.; Haut, Stephen A.

doi:10.1021/jo00914a016

Cited by 30 publications

(8 citation statements)

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“…Several hydrogenolysis reactions challenge the understanding of surface chemistry and are difficult to catalyze selectively, but they hold significant technological and economic potential. As one example, the reduction of esters to yield ethers by direct reduction with hydrogen by reduction and rupture of the carbonyl CO bond would give an ecologically friendly and cost-effective method to prepare ethers in comparison to conventional ether synthesis routes in homogeneous catalysis. ,− Yet, ester hydrogenolysis over solid catalysts generally cleaves the C acyl –O bond to produce alcohols, despite reports of homogeneous systems that do facilitate the required steps. Consequently, the development of heterogeneous analogues requires a greater understanding of the intervening elementary steps and their corresponding site requirements for carbonyl CO reduction and cleavage.…”

Section: Discussionmentioning

confidence: 99%

Advances in Understanding the Selective Hydrogenolysis of Biomass Derivatives

2021

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Biomass has attracted great attention as an alternative to petrochemicals for the production of valuable chemicals and fuels. Hydrogenolysis reactions over heterogeneous catalysts offer pathways to upgrade renewable compounds to a variety of building block molecules; however, similarities among the functional groups in these reactants frequently limit the selectivity of these reactions. Consequently, a fundamental understanding of how oxygenates adsorb, activate, and react upon solid surfaces is essential for catalyst design and reaction engineering. In this Perspective, we describe significant advances in knowledge of the reaction networks and mechanisms, key reactive intermediates, and active site motifs that allow for the selective production of desired compounds by hydrogenolysis over heterogeneous catalysts. These insights draw from the mechanistic understanding gained from comparisons between kinetic measurements, in situ characterization of catalysts and organic intermediates, and ab initio calculations. Drawing from detailed insight taken from a century of study into reactions of hydrogen with hydrocarbons, we discuss the molecular similarities between reactions that cleave C−O and C−C bonds during hydrogenolysis of biomass-derived compounds that range from simple (e.g., alcohols) to polyfunctional molecules (e.g., guaiacol) on monometallic, bimetallic, and nonmetallic catalysts. Finally, we describe current challenges and opportunities for future research into hydrogenolysis reactions.

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Section: Discussionmentioning

confidence: 99%

Advances in Understanding the Selective Hydrogenolysis of Biomass Derivatives

2021

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“…Reaction of an ester with SiHC1, is a common way for the synthesis of the corresponding ether [36], with the highest yields being reported when the reaction is performed without a solvent [37]. The reduction of triolide 1 to 17-19 was carried out according to the procedure reported [37] (Scheme 4 ) ; the crude product mixture could be separated chromatographically, revealing the product distributions indicated in ") According to 'H-NMR spectra of the mixed fractions; yields of actually isolated products in parentheses.…”

Section: )mentioning

confidence: 99%

“…The reduction of triolide 1 to 17-19 was carried out according to the procedure reported [37] (Scheme 4 ) ; the crude product mixture could be separated chromatographically, revealing the product distributions indicated in ") According to 'H-NMR spectra of the mixed fractions; yields of actually isolated products in parentheses.…”

Section: )mentioning

confidence: 99%

Preparation, Structure, and Reactivity of Thioxo and Imino Derivatives of the Triolide (and Pentolide) from (R)‐3‐Hydroxybutanoic Acid

Brunner

Kühnle²,

Seebàch³

1996

Helvetica Chimica Acta

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Reaction of the triolide 1 from (R)-3-hydroxybutanoic acid with Lawesson's reagent 5 leads to the mono-, di-, and trithio derivatives 6-8 which can be isolated in pure form (2040% yields), and which have crystal structures very similar to the parent triolide 1 (Fig.1). Similarly, pentolide 3 is converted to mixtures of various thio derivatives, three of which are separated (1612) by HPLC and fully characterized. The X-ray structures of the mono-and of one of the dithiopentolides (10, 12) differ remarkably from each other (Fig.3). Reduction of the thiotriolides 6-8 (NaBH,, R,SnH, Cl,SiH, Raney -Ni) gives 12-membered rings containing up to three ether groups (chiral crown ethers, 15, 17-19) in poor yields. The thiotriolides react spontaneously and in yields of up to 96% with ammonia, certain primary amines, and hydroxylamine to give imine and oxime derivatives with intact 12-membered-ring backbones (20, 22-24, 30, see crystal structures in Figs. 4-7). The rigid structure of all the derivatives of triolide 1 puts the C=O, C=S, and C=NR 0-, S-, and N-atoms in juxtaposition (a feature reminiscent of the side chains in the iron-binder enterobactin, Fig. 6). Imines containing PPh, groups are prepared (30,33,35) from the thiotriolides and tested as chiral ligands for PdT'-catalyzed 1,3-diphenylallylations (-37, enantiomer ratio up to 77:23). The reactions described demonstrate that multiple reactions of the triolide 1 from (R)-3-hydroxybutanoic acid which proceed through tetrahedral intermediates are possible without ring opening -the skeleton is remarkably stable, and this might be exploited as a template for bringing up to three pendent substituents into close proximity to allow a study of their interactions and cooperative properties. Also, the di-and trithio derivatives 7 and 8 could be used for cross-linking in molecules containing primary NH2 groups.

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“…[66][67][68] For the series of alkyl esters reduction to ethers in 80-100% yield is reported. In analogy to addition of silanes to the carbonyl group, the mechanism of reduction was proposed (Scheme 15).…”

Section: Reductions By Silanes and Lewis Acidsmentioning

confidence: 99%

“…In analogy to addition of silanes to the carbonyl group, the mechanism of reduction was proposed (Scheme 15). 68 Cl 3 SiH/-rays Cl 3 SiH + Cl 3 SiH + Cl 3 Si-O-SiCl 3…”

Section: Reductions By Silanes and Lewis Acidsmentioning

confidence: 99%

Ethers from esters; from exceptional transformation to synthetic method

Jakopović¹,

Kapić²,

Alihodžić³

et al. 2015

Arkivoc

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Most ether-bond forming reactions based on traditional methods or modifications thereof require strongly acidic or basic conditions and often harsh reaction conditions. Reduction of esters to ethers has been regarded as an impracticable method, generally affording alcohols as the principal products. Only recently, original, mostly catalytic methods for reduction of esters to ethers have been reported, which proceed under mild conditions and are compatible with many functional groups present in the substrate ester molecule. These reactions are considered as a valuable alternative to traditional methods, and specific protocols have been reported. An account of the progress in this synthetic methodology is given.

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Reductive deoxygenation of esters with trichlorosilane

Cited by 30 publications

References 4 publications

Advances in Understanding the Selective Hydrogenolysis of Biomass Derivatives

Advances in Understanding the Selective Hydrogenolysis of Biomass Derivatives

Preparation, Structure, and Reactivity of Thioxo and Imino Derivatives of the Triolide (and Pentolide) from (R)‐3‐Hydroxybutanoic Acid

Ethers from esters; from exceptional transformation to synthetic method

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