Preparation of .beta.-keto esters by 4-DMAP-catalyzed ester exchange

Taber, Douglass F.; Amedio, John C.; Patel, Yogesh

doi:10.1021/jo00219a035

Cited by 147 publications

(65 citation statements)

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“…A mixture of guanidine 9 (1.70 mmol), β-keto ester 11 (1.96 g, 5.1 mmol), morpholinium acetate (250 mg, 1.7 mmol), Na 2 SO 4 (250 mg), and trifluoroethanol (3.5 mL) was heated at 60 °C for 2 d. After cooling to room temperature, the mixture was filtered, and concentrated. 4R,7R,8aR)-4-[6R-Hydroxynonyl]-7-methyl-1,2,2a,3,4,5,6,7,8,8a-decahydro-5,6,8b-triazaacenaphthylenium tetrafluoroborate (13) A solution of guanidine ester 12 (200 mg, 0.35 mmol), (PPh 3 ) 4 Pd (10 mg, 0.009 mmol), pyrrolidine (140 μL, 1.7 mmol), THF (2 mL), and MeOH (2 mL) was maintained at room temperature. After 6 h, the reaction was concentrated and acetic acid (5 mL) was added.…”

Section: Resultsmentioning

confidence: 99%

Enantioselective Total Synthesis of Batzelladine F and Definition of Its Structure.

Cohen

Overman

2006

ChemInform

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Batzelladine F (1) was synthesized in enantioselective and stereoselective fashion in 15 steps (longest linear sequence) and 1.7% overall yield from two readily available enantioenriched β-hydroxy esters, methyl (R)-3-hydroxydecanoate and methyl (R)-3-hydroxybutyrate. Tethered Biginelli condensations are used to assemble both tricyclic guanidine fragments, with the second tethered Biginelli condensation (14 + 16 → 17) also being employed to join the guanidine fragments. Three diastereomers of batzelladine F, 2−4, were prepared also. A combination of HPLC, optical rotation and CD spectroscopy was employed to distinguish stereoisomers 1−4, proving that 1 is the correct structure of the hexacyclic marine alkaloid batzelladine F.

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Section: Resultsmentioning

confidence: 99%

Enantioselective Total Synthesis of Batzelladine F and Definition of Its Structure.

Cohen

Overman

2006

ChemInform

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“…Transesterification (Scheme 2), reactions producing esters by catalytical alcoholysis of other esters, also play an important role in the industry, for instance in the manufacture of glycerol esters in fat chemistry (e.g., biodiesel), the transesterification of dimethyl carbonate to diethyl carbonate, or the production of polyethylene terephthalate from dimethyl terephthalate. For these reactions, the usual catalysts are Brønsted mineral acids (H 3 PO 4 , H 2 SO 4 , HCl) [24][25][26], and organic acids such as MeSO 3 H and p-toluenesulfonic acid (TsOH) [27], alkoxides such as NaOR, KOR, ROMgBr [28][29][30][31][32], Lewis bases such as 4-dimethylaminopyridine (DMAP) [33,34], 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) [35], Lewis acids such as BX 3 [36], or AlCl 3 [37], amphoteric Catalysts 2016, 6, 128 5 of 65 compounds (compounds able to react either as acids or bases) such as Bu 3 SnOR [38][39][40][41], perfluorotin oxides [42], Al(OR) 3 [43,44], titanium oxides chlorides [45][46][47][48] or palladium oxides [49,50]. More recently, diaminocarbenes have been introduced as catalysts as well [51][52][53][54].…”

Section: Acyl Group Transfersmentioning

confidence: 99%

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

et al. 2016

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Catalysis fulfills the promise that high-yielding chemical transformations will require little energy and produce no toxic waste. This message is carried by the study of the evolution of molecular catalysis of some of the most important reactions in organic chemistry. After reviewing the conceptual underpinnings of catalysis, we discuss the applications of different catalysts according to the mechanism of the reactions that they catalyze, including acyl group transfers, nucleophilic additions and substitutions, and C-C bond forming reactions that employ umpolung by nucleophilic additions to C=O and C=C double bonds. We highlight the utility of a broad range of organocatalysts other than compounds based on proline, the cinchona alkaloids and binaphthyls, which have been abundantly reviewed elsewhere. The focus is on organocatalysts, although a few examples employing metal complexes and enzymes are also included due to their significance. Classical Brønsted acids have evolved into electrophilic hands, the fingers of which are hydrogen donors (like enzymes) or other electrophilic moieties. Classical Lewis base catalysts have evolved into tridimensional, chiral nucleophiles that are N-(e.g., tertiary amines), P-(e.g., tertiary phosphines) and C-nucleophiles (e.g., N-heterocyclic carbenes). Many efficient organocatalysts bear electrophilic and nucleophilic moieties that interact simultaneously or not with both the electrophilic and nucleophilic reactants. A detailed understanding of the reaction mechanisms permits the design of better catalysts. Their construction represents a molecular science in itself, suggesting that sooner or later chemists will not only imitate Nature but be able to catalyze a much wider range of reactions with high chemo-, regio-, stereo-and enantioselectivity. Man-made organocatalysts are much smaller, cheaper and more stable than enzymes.

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“…The present investigation was undertaken to assess the reactivity of pyridine bases towards tribenzyltin chloride. 4-(Dimethylamino)pyridine (DMAP) was chosen because of its catalytic [7], basic and ligation properties [8].…”

Section: Introductionmentioning

confidence: 99%

Ligation to tin(IV) organometallics: crystal structure of tribenzyl(chloro)(4-N,N′-dimethylaminopyridine)tin(IV)

Chandrasekar

Krishnamoorthy

Sridevi

et al. 2005

Journal of Coordination Chemistry

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The preparation and characterization of the air-stable, five-coordinate complex of 4-(dimethylamino)pyridine with tribenzyltin chloride is reported. The complex crystallizes in space group P2 1 /n with a ¼ 10.3743 (17) (15) . Single crystal X-ray analysis confirms the structure to be monomeric in which the geometry around tin is a trigonal bipyramid with equatorial benzyl groups. The 119 Sn NMR signal of the complex in CDCl 3 occurs upfield with respect to the corresponding signal in (C 6 H 5 CH 2 ) 3 SnCl, indicating lack of dissociation of the ligand in solution. Computations using the PM3 hamiltonian for the complex yielded a trigonal bipyramidal structure with satisfactory agreement in metrical parameters with those obtained from X-ray analysis.

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Preparation of .beta.-keto esters by 4-DMAP-catalyzed ester exchange

Cited by 147 publications

References 0 publications

Enantioselective Total Synthesis of Batzelladine F and Definition of Its Structure.

Enantioselective Total Synthesis of Batzelladine F and Definition of Its Structure.

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

Ligation to tin(IV) organometallics: crystal structure of tribenzyl(chloro)(4-N,N′-dimethylaminopyridine)tin(IV)

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