Silyl Glyoxylates. Conception and Realization of Flexible Conjunctive Reagents for Multicomponent Coupling

Boyce, Gregory R.; Greszler, Stephen N.; Johnson, Jeffrey S.; Linghu, Xin; Malinowski, Justin T.; Nicewicz, David A.; Satterfield, Andrew D.; Schmitt, Daniel C.; Steward, Kimberly M.

doi:10.1021/jo300184h

Cited by 57 publications

(27 citation statements)

References 139 publications

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“…11 In light of the prominence and utility of DKR reactions of α-stereogenic-β-keto esters, the absence of complementary isomeric variants from racemic α-keto esters was surprising. As part of our laboratory’s continued interest in glycolic acid synthesis, 12 we have recently developed a highly stereoselective dynamic kinetic resolution of β-stereogenic-α-keto esters via asymmetric transfer hydrogenation (DKR-ATH), yielding trisubstituted γ-butyrolactones ( vide infra ). 13 It occurred to us that substantial product diversity might arise from a common mechanistic platform simply by varying the identities of the nonhydrogen substituents (X and Y) at the β-carbon.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Synthesis of Diverse Glycolic Acid Scaffolds via Dynamic Kinetic Resolution of α-Keto Esters

et al. 2012

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The dynamic kinetic resolution of α-keto esters via asymmetric transfer hydrogenation has been developed as a technique for the highly stereoselective construction of structurally diverse β-substituted-α-hydroxy carboxylic acid derivatives. Through the development of a privileged m-terphenylsulfonamide for (arene)RuCl(monosulfonamide) complexes with a high affinity for selective α-keto ester reduction, excellent levels of chemo-, diastereo-, and enantiocontrol can be realized in the reduction of β-aryl- and β-chloro-α-keto esters.

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Section: Introductionmentioning

confidence: 99%

Asymmetric Synthesis of Diverse Glycolic Acid Scaffolds via Dynamic Kinetic Resolution of α-Keto Esters

et al. 2012

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“…15 During the development of a nucleophilic glyoxylation employing silyl glyoxylate 4 and aldehydes (i.e., benzaldehyde 5 ), the sensitivity of the derived β -silyloxy- α -keto ester 6 toward base promoted conversion to isomeric β -keto ester 7 was noted. This observation prompted the realization that α -keto esters such as 6 might succumb to facile racemization and thereby hold potential as precursors to diol derivatives such as 8 via dynamic reduction (Scheme 2).…”

Section: Transfer Hydrogenation Dynamic Kinetic Resolutions Of α-Kmentioning

confidence: 99%

“…In contrast, the addition of carbon-nucleophiles should provide expanded access to diverse scaffolds. Due to our group's interest in complex glycolates, 15 the development of enantioconvergent C -centered nucleophile additions to α -keto esters emerged as a compelling means to generate tertiary glycolates. We first targeted the addition of pro-nucleophiles nitromethane and acetone to β -bromo- α -keto esters 36 (Scheme 8).…”

Section: Dynamic Kinetic 12-addition Of Carbon-centered Nucleophilesmentioning

confidence: 99%

Synthesis of Complex Glycolates by Enantioconvergent Addition Reactions

Bartlett

Johnson

2017

Acc. Chem. Res.

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Conspectus The unique role that stereochemistry plays in molecular recognition events continues to provide a driving force for synthesizing organic compounds in enantioenriched form. The tendency of enantioenriched organic compounds to revert to an entropically favored racemic state in the presence of viable racemization pathways (e.g., the enolization of stereogenic carbonyl derivatives) can sometimes interfere with this objective; however, beginning with Noyori's foundational disclosure of a dynamic kinetic transfer hydrogenation, the ability to channel racemic, configurationally labile starting materials through stereoconvergent reaction pathways has been recognized as a powerful strategy in asymmetric synthesis. Proton transfer, retro-aldol, retro-Michael, reversible redox events, and other processes that can be deleterious to asymmetric synthesis are exploitable in enantioconvergent reactions using chiral small molecules and enzymes as asymmetric catalysts. Enantioselective reduction of configurationally labile carbonyl derivatives bearing a C–H acidic chiral center are particularly common. Because facile racemization is vital to stereocontrol in these transformations, hydrogenations of β-dicarbonyls are commonplace, while less activated substrates have been used less commonly. Our entry into enantioconvergent catalysis evolved from a long-standing interest in the synthesis of complex glycolates and began with the development of a general Noyori-type transfer hydrogenation of α-keto esters. Key innovations in this work include the identification of a new terphenylsulfonamide–Ru(II) complex, which displays unusual preference toward reduction of α-keto esters, and the observation that α-keto esters racemize under mildly basic conditions. This work was extended to the dynamic kinetic hydrogenation of racemic acyl phosphonates. Moreover, the recent recognition that the mechanistic paradigm underlying enantioconvergent hydrogenation chemistry can be extended to diverse carbon-centered nucleophiles has led to advances in the art. Our lab has developed a number of enantioconvergent tertiary alcohol syntheses. In the context of carbon-centered nucleophiles, we have focused on the use of α-keto esters; however, in the latter part of this Account, we will briefly describe our nascent efforts to develop dynamic kinetic additions of carbon-centered nucleophiles to β-oxo acid derivatives. While the enantioconvergent hydrogenation of β-keto acid derivatives is carried out on 100-ton scale annually, non-hydrogenative transformations of these compounds constitute an underexplored subclass of enantioconvergent reactions. With regard to future prospects, a trend toward transformations that afford increasing levels of molecular complexity is apparent. It can be expected that the burgeoning field of asymmetric 1,2-addition chemistry will further drive this chemistry to encompass a wider array of enantioconvergent additions. Additionally, the continued exploration of these chemistries in the context of less conventional electro...

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“…Acylsilanes or α-silyl ketones have been known as a unique class of silicon compounds [1][2][3][4][5][6][7][8][9], showing remarkably red-red shifted n→π* transition bands [1,2] and being useful as distinct reagents in organic synthesis [4][5][6][10][11][12][13][14][15][16][17][18][19]. Most of all, acyltris(trimethylsilyl)silanes are of particular importance, which were utilized for the synthesis of the first stable silicon-carbon doubly bonded compounds (silenes) [20,21].…”

Section: Introductionmentioning

confidence: 99%

Reactions of an Isolable Dialkylsilylene with Aroyl Chlorides. A New Route to Aroylsilanes

et al. 2016

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Abstract:The reactions of isolable dialkylsilylene 1 with aromatic acyl chlorides afforded aroylsilanes 3a-3c exclusively. Aroylsilanes 3a-3c were characterized by 1 H-, 13 C-, and 29 Si-NMR spectroscopy, high-resolution mass spectrometry (HRMS), and single-crystal molecular structure analysis. The reaction mechanisms are discussed in comparison with related reaction of 1 with chloroalkanes and chlorosilanes.

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Silyl Glyoxylates. Conception and Realization of Flexible Conjunctive Reagents for Multicomponent Coupling

Cited by 57 publications

References 139 publications

Asymmetric Synthesis of Diverse Glycolic Acid Scaffolds via Dynamic Kinetic Resolution of α-Keto Esters

Asymmetric Synthesis of Diverse Glycolic Acid Scaffolds via Dynamic Kinetic Resolution of α-Keto Esters

Synthesis of Complex Glycolates by Enantioconvergent Addition Reactions

Reactions of an Isolable Dialkylsilylene with Aroyl Chlorides. A New Route to Aroylsilanes

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