Top PDF Process for the synthesis of α, β-unsaturated esters

Process for the synthesis of α, β unsaturated esters

Process for the synthesis of α, β-unsaturated esters

Ahexanes solution of FeCO5 13.3 mM With 10 42% after 5 hours see Table 2, entry 6, beloW; this is less than the 70% yield of the ot, [3-ester 7 obtained from the reaction at loWer concen[r]

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Multiple roles of aryloxide leaving groups in enantioselective annulations employing α,β unsaturated acyl ammonium catalysis

Multiple roles of aryloxide leaving groups in enantioselective annulations employing α,β unsaturated acyl ammonium catalysis

The isothiourea-catalysed enantioselective synthesis of a range of polyuorinated dihydropyranone and dihydropyridinone products was achieved via a Michael addition–annulation process using a,b-unsaturated acyl ammonium catalysis (29 examples, up to 98%, >99 : 1 er). b-Fluoroalkyl-substituted a,b- unsaturated trichlorophenyl esters were used as the a,b-unsat- urated acyl ammonium precursors, and a range of 2-acyl(benz) azoles used as the nucleophilic reaction partner. Signicantly, the trichlorophenoxide leaving group was shown to play a variety of other roles in the reaction, including acting as (i) a Brønsted base, circumventing the need for the addition of an auxiliary base; and (ii) a Lewis base, catalysing the isomerisation of dihydropyranone products into thermodynamically-favoured dihydropyridinones. The isomerisation process was most effi- cient using less sterically-hindered aryloxide catalysts bearing electron-withdrawing groups, such as 3,5-bis(triuoromethyl) phenoxide, 3,4,5-triuorophenoxide or para-nitrophenoxide. These ndings led to the development of a sequential Michael addition–annulation–isomerisation protocol for the synthesis of a range of benzothiazole-derived dihydropyridinone products as the only constitutional isomer in excellent yield and enantio- control. The method could also be applied when using 2-acyl- benzoxazole pro-nucleophiles, with the selective formation of either dihydropyranones or dihydropyridinones achieved by including or omitting the isomerisation step. The aryloxide- promoted isomerisation protocol was further applied to our previously-reported Michael addition–annulation process using
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Enantioselective synthesis of β fluoro β aryl α amino pentenamides by organocatalytic [2,3] sigmatropic rearrangement

Enantioselective synthesis of β fluoro β aryl α amino pentenamides by organocatalytic [2,3] sigmatropic rearrangement

gave selective [2,3]-rearrangement at the (Z)-3-fluoro-3- phenylprop-2-ene group, giving 17 with good stereocontrol (64%, 92:8 dr, 87:13 er). Higher diastereo- and enantioselec- tivity, but reduced yield, was observed in EC (54%, 95:5 dr, 91:9 er). Further investigation showed that a wide range of cyclic nitrogen substituents are tolerated in this process, with pyrrolidinyl, piperidinyl and azepanyl derivatives 18–20 being prepared in good yields and with high diastereo- and enantio- control (62 – 69%, 91:9 – 94:6 dr, 95:5 – 98:2 er). Alternative nitrogen heterocycles (isoindolyl, 4,5,6,7-tetrahydrothieno- [3,2-c]pyridinyl, N-Boc piperazinyl and morpholinyl) were also successfully incorporated giving products 21–24 with generally good yields and stereoselectivity (up to 92:8 dr and 91:9 er). However, attempted chromatographic purification of 22 led to extensive decomposition, while trituration allowed its isolation but in a poor 14% yield.
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Synthesis, Reactions and Biological Importance of α, β-Unsaturated Carbodithioate Esters: A Review

Synthesis, Reactions and Biological Importance of α, β-Unsaturated Carbodithioate Esters: A Review

Interestingly, α, β-unsaturated thioesters have marked reactivity as Michael acceptors and they are proved to be excellent substrates in the synthesis of several natural products [22]. Although, it is a very useful intermediate, traditional syntheses of thioesters are encountered with the occasional difficulties such as 1,4-addition of thiolate and subsequent separation from the main product [23]. Olefin cross-metathesis has been elegantly explored to construct α, β-unsaturated thioesters using thioacrylate [24]. Encouraged by the success of synthesis of α, β-unsaturated esters, A.R. Mohite et al [25]. planned to extend the protocol for the straightforward synthesis of α, β-unsaturated thioesters using the optimized reaction conditions for esters. To compare the reactivity and to extend the application, thiols 13 (1 eq.) were treated with few benzylidene derivative of MA 12 under optimized reaction conditions (Scheme 4). The corresponding α, β-unsaturated thioesters 14 were obtained in good to excellent yields (76–90%) in just 30 min (Scheme 4).
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Anhydrides as α,β unsaturated acyl ammonium precursors : isothiourea promoted catalytic asymmetric annulation processes

Anhydrides as α,β unsaturated acyl ammonium precursors : isothiourea promoted catalytic asymmetric annulation processes

To conclude, HBTM 2.1 5 promotes the asymmetric annula- tion of a range of nucleophiles including 1,3-diketones, b-ketoesters and azaaryl ketones to (E,E)-a,b-unsaturated anhydrides, giving either functionalised esters (upon ring opening), dihydropyranones, or dihydropyridones in good yields (up to 86%) and high enantioselectivity (up to 97% ee) via a postulated a,b-unsaturated acyl ammonium interme- diate. Current research from this laboratory is directed toward developing alternative uses of isothioureas and other Lewis bases in asymmetric catalysis, and exploiting a,b- unsaturated acyl ammonium intermediates for a range of synthetic procedures.
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Synthesis of α-hydroxy-β,β-difluoro-γ-ketoesters via [3,3]sigmatropic rearrangements

Synthesis of α-hydroxy-β,β-difluoro-γ-ketoesters via [3,3]sigmatropic rearrangements

Readily available γ , γ -di fl uorinated allylic alcohols obtained from tri fl uoroethanol were esteri fi ed e ffi ciently. Exposure to strong base (LDA) a ff orded the ester enolates, in which chelation both controlled con fi guration and stabilised against fragmentation, which were trapped as their silyl ketene acetals. Rearrangement occurred to a ff ord base-sensitive acid products. Esteri fi cation under mild conditions a ff orded the puri fi able methyl esters in which the masked ketone had been released. Educts with either a benzyloxy or an allyloxy group at the α -position could be deprotected releasing the alcohols.
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Poly Ethylene Glycols as Efficient Media for the Synthesis of β Nitro Styrenes from α, β Unsaturated Carboxylic Acids and Metal Nitrates under Conventional and Non Conventional Conditions

Poly Ethylene Glycols as Efficient Media for the Synthesis of β Nitro Styrenes from α, β Unsaturated Carboxylic Acids and Metal Nitrates under Conventional and Non Conventional Conditions

conditions [28]. Polyethylene glycol (PEG-400) is a bio- logically acceptable inexpensive polymer and an eco- friendly reagent [29], which is widely used in many or- ganic reactions for conversion of oxiranes to thiiranes [30], asymmetric aldol reactions [31], cross-coupling rea- ctions [18], Baylis-Hillman reaction [32,33] and ring o- pening of epoxides [34]. Encouraged by these results, we want to explore, the use of Polyethylene glycols (PEGs) as efficient catalyst in this study. We have studied PEG triggered Hunsdiecker-Borodin reactions for the synthe- sis of β-nitro styrenes from α, β-unsaturated carboxylic acids under conventional and non-conventional (solvent free mortar-pestle and microwave) conditions.
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Conjugate Addition of Indoles to α,β Unsaturated Ketones Using Bismuth (III) Bromide

Conjugate Addition of Indoles to α,β Unsaturated Ketones Using Bismuth (III) Bromide

[34] Salvador, J.A.R., Silvestre, S.M., Pinto, R.M.A., Santos, R.C. and LeRoux, C. (2012) New Applications for Bismuth (III) Salts in Organic Synthesis: From Bulk Chemi- cals to Steroid and Terpene Chemistry. Topics in Current Chemistry , 311, 143-178. https://doi.org/10.1007/128_2011_170

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SbCl3 HAP catalyzed aza Michael addition of aliphatic amines to α,β  unsaturated carbonyl compounds and nitriles

SbCl3 HAP catalyzed aza Michael addition of aliphatic amines to α,β unsaturated carbonyl compounds and nitriles

The aza-Michael addition is one of the widely used reactions for carbon-nitrogen bond formation in synthetic organic chemistry. Michael addition of various amines to α,β-unsaturated carbonyl compounds and nitriles provide the corresponding β-amino derivatives, which have attracted great attention for their use as important synthons for the synthesis of several nitrogen containing bioactive natural products [1], chiral auxiliaries [2], antibiotics [3] and a number of other drugs [4]. The development of novel synthetic methodologies for the preparation of these compounds is an attractive area of research in organic chemistry. A variety of methods are known in the literature for the synthesis of β-amino carbonyl compounds and nitriles. Among these, the most common route is the Michael addition of nitrogen nucleophiles to α,β- unsaturated compounds and nitriles in the presence of an acid or a base catalyst [5]. Generally, aza-Michael addition has been catalyzed by strong acids and bases, and some side reactions occurred. As a result, various Lewis acid catalysts have been reported to effect aza-Michael reaction and these include Yb(OTf 3 ) [6], PtCl 4 ·5H 2 O [7], Cu(OTf) 2 [8], FeCl 3 .6H 2 O [9], LiClO 4 [10], Bi(NO 3 ) [11], InCl 3 [12],
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Enantioselective NHC catalyzed redox [4+2] hetero Diels Alder reactions using α,β unsaturated trichloromethyl ketones as amide equivalents

Enantioselective NHC catalyzed redox [4+2] hetero Diels Alder reactions using α,β unsaturated trichloromethyl ketones as amide equivalents

(20) For selected recent uses of trichloromethyl ketones in natural product synthesis and medicinal chemistry, see: (a) Wu, P.; Zhang, J.; Meng, Q.; Nare, B.; Jacobs, R. T.; Zhou, H. Eur. J. Med. Chem. 2014, 81, 59-75. (b) Rodriguez, R. A.; Barrios Steed, D.; Kawamata, Y.; Su, S.; Smith, P. A.; Steed, T. C.; Romesberg, F. E.; Baran, P. S. J. Am. Chem. Soc. 2014, 136, 15403-15413. (c) Hirata, A.; Nokihara, K.; Kawamoto, Y.; Bando, T.; Sasaki, A.; Ide, S.; Maeshima, K.; Kasama, T.; Sugiyama, H. J. Am. Chem. Soc. 2014, 136, 11546-11554. (d) Grosse, S.; Mathieu, V.; Pillard, C.; Massip, S.; Marchivie, M.; Jarry, C.; Bernard, P.; Kiss, R.; Guillaumet, G. Eur. J. Med. Chem. 2014, 84, 718-730.
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ABSTRACT : This study deals with synthesis and curing of cellulose esters from renewable resources. Cellulose esters

ABSTRACT : This study deals with synthesis and curing of cellulose esters from renewable resources. Cellulose esters

In order to investigate the mechanical properties of the resulting films, the temperature dependence of dynamic viscoelasticity was measured. For the film from 2a, the storage modulus fell off slowly in the broad temperature range, and two peaks of loss factor were revealed at 10 and 60°C Figure 3. The relaxation at higher temperature was accompanied by the most important decrease of E’, and it corresponded to the glass transition of the film. The β transition at lower temperature might be caused by the side chain motion of oleic acid. Lateral aliphatic chains can readily associate with one another, creating local crystalline structures. With increasing temperature, the local crystalline structures melt and cause a relaxation. On the other hand, a peak and smooth traces of loss factor was observed in the films from 2b and 2c, indicating the homogeneous structure of the resulting films. The glass transition temperature (Tg) of the films from 2b and 2c were higher than that of the film from 2a, and increased with increasing the numbers of unsaturated groups in the side chain. These may be due to the restricted mobility of the aliphatic chain by the cross linked structure. Above Tg, the storage modulus were almost constant, suggesting that the almost all of unsaturated groups in the side chain were reacted.
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Efficient Synthesis of β-Lactam-Containing α-Aminophosphonates Using Fumaric Acid as Mild Catalyst

Efficient Synthesis of β-Lactam-Containing α-Aminophosphonates Using Fumaric Acid as Mild Catalyst

The original syntheses of α-amino phosphonate esters (1) involved the use of aldehyde/ketone, amine and dialkyl/trialkyl phosphites in the presence of an acid or a base under harsh conditions, but those methods were incapable for the synthesis in presence of sensitive functional groups such as β-lactam. Hence, finding the milder reaction conditions was crucial to obtain novel β-lactam containing α-amino phosphonate esters. Cognizant of the sensitivity of β-lactam functionality present in one of the reactants and subsequently in the final products, milder acidic conditions were explored. Initially, trials involving the conversion of N-(4-methoxyphenyl)-2-(substituted) propiolactam-3-carbaldehydes (3a-3c) and aromatic amine to the corresponding imine, followed by treatment of the isolated imine with triethyl phosphite under Pudovik reaction conditions did not yield the required product. During those trials, the unsubstituted aniline 4a and substituted anilines 4b-4d also didn’t yield any success. Similarly, seemingly straightforward trials of one-pot Kabachnik-Fields reaction between N-(4-methoxyphenyl)-2-(substituted) propiolactam-3- carbaldehyde (3a-3c), aromatic amine (4a-4c) and triethyl phosphite in the presence of p-TsOH were attempted, but without success. Hence, we decided to explore Kabachnik-Fields type reaction conditions using mild acidic catalysts.
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Highly efficient aqueous phase chemoselective hydrogenation of α,β-unsaturated aldehydes catalysed by phosphine-decorated polymer immobilized IL-stabilized PdNPs

Highly efficient aqueous phase chemoselective hydrogenation of α,β-unsaturated aldehydes catalysed by phosphine-decorated polymer immobilized IL-stabilized PdNPs

Gratifyingly, 2c is also an efficacious catalyst for chemoselective hydrogenation of the C=C bond in - unsaturated esters and nitriles giving the desired product in high yield and 100% selectivity at room temperature after only 2 h. Finally, 2c also catalyses the aqueous phase reduction of aromatic nitro compound with remarkable efficiency to afford the corresponding amines as the sole product in quantitative yield under mild conditions.

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Highly efficient aqueous phase chemoselective hydrogenation of α,β-unsaturated aldehydes catalysed by phosphine-decorated polymer immobilized IL-stabilized PdNPs

Highly efficient aqueous phase chemoselective hydrogenation of α,β-unsaturated aldehydes catalysed by phosphine-decorated polymer immobilized IL-stabilized PdNPs

Gratifyingly, 2c is also an efficacious catalyst for chemoselective hydrogenation of the C=C bond in  -unsaturated esters and nitriles giving the desired product in high yield and 100% selectivity at room temperature after only 2 h. Finally, 2c also catalyses the aqueous phase reduction of aromatic nitro compound with remarkable efficiency to afford the corresponding amines as the sole product in quantitative yield under mild conditions.

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Cp*Co(III) Catalyzed coupling of benzamides with α,β unsaturated carbonyl compounds: Preparation of aliphatic ketones and azepinones

Cp*Co(III) Catalyzed coupling of benzamides with α,β unsaturated carbonyl compounds: Preparation of aliphatic ketones and azepinones

Abstract: A Cp*Co(III)-catalyzed C-H functionalization of benzamide substrates with ,-unsaturated ketones has been optimized, providing a facile route towards aliphatic ketone products. When employing ,-unsaturated aldehydes as coupling partners, under the optimized protocol, a cascade reaction forming azepinones has also been developed. Finally, DFT studies have demonstrated how stabilization of a metallo-enol intermediate when employing ,- unsaturated ketones is the driving force leading to the observed aliphatic ketone product rather than olefinic products reported using ,-unsaturated esters as coupling partners.
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Synthesis and Anti microbial activity of a new class of α Aminophosphonic acid esters by using TMG as Catalyst

Synthesis and Anti microbial activity of a new class of α Aminophosphonic acid esters by using TMG as Catalyst

In this connection we prepared a new class of α-aminophoshonic acid esters (3a-j) has been synthesized by the addition of labile P-H to Schiff’s bases in a one-pot Pudovik reaction. Previous results demonstrated that tetramethylguanidine (TMG) catalyzes the Michael addition of nitro methane to α, β-unsaturated ketones [13,14]. These results prompted us to take various aldimines as a starting compound for the synthesis of title compounds. Keeping in view the importance of α-aminophosphonates and several other possible applications, we report herein the synthesis, spectral characterization and antimicrobial activity.
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Aryloxide facilitated catalyst turnover in enantioselective α,β unsaturated acyl ammonium catalysis

Aryloxide facilitated catalyst turnover in enantioselective α,β unsaturated acyl ammonium catalysis

[11] For examples of using aryl esters as azolium enolate and a,b- unsaturated acyl azolium precursors see: a) L. Hao, Y. Du, H. Lv, X. Chen, H. Jiang, Y. Shao, Y. R. Chi, Org. Lett. 2012, 14, 2154 – 2157; b) J. Cheng, Z. Huang, Y. R. Chi, Angew. Chem. Int. Ed. 2013, 52, 8592 – 8596; Angew. Chem. 2013, 125, 8754 – 8758; c) Z. Fu, X. Wu, Y. R. Chi, Org. Chem. Front. 2016, 3, 145 – 149. [12] For a recent review of isothiourea catalysis see: J. Merad, J.-M. Pons, O. Chuzel, C. Bressy, Eur. J. Org. Chem. 2016, 5589 – 5610. [13] a) L. S. Aitken, N. R. Arezki, A. DellIsola, A. J. A. Cobb, Synthesis 2013, 2627 – 2648; b) R. Ballini, G. Bosica, D. Fiorini, A. Palmieri, M. Petrini, Chem. Rev. 2005, 105, 933 – 971. [14] Yields determined by 1 H NMR spectroscopy using an internal
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Synthesis of Some New Pyrazoline Compounds Derived from α-β Unsaturated Compounds and Study their biological and Biochemical Effect

Synthesis of Some New Pyrazoline Compounds Derived from α-β Unsaturated Compounds and Study their biological and Biochemical Effect

Treatment with hydrogen peroxide (0.1%) by mouth with drinking water and for (15) days in male white rats as shown in Table (6) to a significant increase (P˂0.01) in serum glucose level when compared with the control group, this may be due to an increase in oxygen pressure from hydrogen peroxide and thus to an increase in the active oxygen species that attack beta cells in the pancreas, disrupting insulin synthesis [42].

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Microwave induced novel synthesis and characterization of 3,5-diaryl-∆2-isoxazoline” from α, β-unsaturated carbonyl compounds

Microwave induced novel synthesis and characterization of 3,5-diaryl-∆2-isoxazoline” from α, β-unsaturated carbonyl compounds

isoxazolines (4a-k) microwave assisted solid support methodusing basic alumina was found better method in comparison to classical as well as solution phase MWl method and gave shorter reaction time, higher yield and solvent free condition with easy experimental manipulation. The synthesized compound may serve as useful intermediate for the synthesis of structurally diverse heterocyclic compounds. Significant anti- microbial activity was observed with synthesized compounds against bacteria and fungi.

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Isothiourea catalysed enantioselective Michael addition of N heterocyclic pronucleophiles to α,β unsaturated aryl esters

Isothiourea catalysed enantioselective Michael addition of N heterocyclic pronucleophiles to α,β unsaturated aryl esters

Following our previous mechanistic investigations, 19 a proposed catalytic cycle is outlined in Scheme 3. Catalysis is initiated through rapid and reversible catalyst acylation by the a,b-unsaturated PNP ester 1 to give a,b-unsaturated acyl iso- thiouronium ion pair 82. Deprotonation of the pronucleophile by the released p-nitrophenoxide, 28 followed by Michael addi- tion of the resultant enolate to the a , b -unsaturated acyl iso- thiouronium 82, in the assumed stereo-determining step, will generate isothiouronium enolate 83. Subsequent protonation, presumably by the generated p-nitrophenol, gives acyl iso- thiouronium ion pair 84. Finally, catalyst turnover either directly by p-nitrophenoxide, or by intramolecular participation from the oxindole C]O to give 86, followed by addition of p- nitrophenoxide, gives the Michael addition product 87 and
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