5466-78-4Relevant academic research and scientific papers
An expedient stereoselective synthesis of (E)-α,β-unsaturated esters and thioesters using FeCl3·6H2O
Mohite, Amar R.,Mete, Trimbak B.,Bhat, Ramakrishna G.
, p. 770 - 774 (2017/03/31)
Facile and convenient synthesis of α,β-unsaturated esters and thioesters from alkylidene derivatives of Meldrum's Acid is described. This method uses catalytic amount of FeCl3·6H2O (0.001–0.005?equiv) with alcohols/thiols (1?equiv) in dry CH3NO2 followed by catalytic amount of piperidine. A variety of α,β-unsaturated esters and thioesters have been synthesized with high E-stereoselectivity in good to excellent yields. The application of this methodology is demonstrated by gram scale synthesis of octinoxate, a sunscreen agent, and other p-methoxycinnamate esters.
Catalytic, Enantioselective β-Protonation through a Cooperative Activation Strategy
Wang, Michael H.,Barsoum, David,Schwamb, C. Benjamin,Cohen, Daniel T.,Goess, Brian C.,Riedrich, Matthias,Chan, Audrey,Maki, Brooks E.,Mishra, Rama K.,Scheidt, Karl A.
, p. 4689 - 4702 (2017/05/12)
The NHC-catalyzed transformation of unsaturated aldehydes into saturated esters through an organocatalytic homoenolate process has been thoroughly studied. Leveraging a unique “Umpolung”-mediated β-protonation, this process has evolved from a test bed for homoenolate reactivity to a broader platform for asymmetric catalysis. Inspired by our success in using the β-protonation process to generate enals from ynals with good E/Z selectivity, our early studies found that an asymmetric variation of this reaction was not only feasible, but also adaptable to a kinetic resolution of secondary alcohols through NHC-catalyzed acylation. In-depth analysis of this process determined that careful catalyst and solvent pairing is critical for optimal yield and selectivity; proper choice of nonpolar solvent provided improved yield through suppression of an oxidative side reaction, while employment of a cooperative catalytic approach through inclusion of a hydrogen bond donor cocatalyst significantly improved enantioselectivity.
Mechanistic Investigations of the Pd(0)-Catalyzed Enantioselective 1,1-Diarylation of Benzyl Acrylates
Orlandi, Manuel,Hilton, Margaret J.,Yamamoto, Eiji,Toste, F. Dean,Sigman, Matthew S.
supporting information, p. 12688 - 12695 (2017/09/22)
A mechanistic study of the Pd-catalyzed enantioselective 1,1-diarylation of benzyl acrylates that is facilitated by a chiral anion phase transfer (CAPT) process is presented. Kinetic analysis, labeling, competition, and nonlinear effect experiments confirm the hypothesized general mechanism and reveal the role of the phosphate counterion in the CAPT catalysis. The phosphate was found to be involved in the phase transfer step and in the stereoinduction process, as expected, but also in the unproductive reaction that provides the traditional Heck byproduct. Multivariate correlations revealed the CAPT catalyst's structural features, affecting the production of this undesired byproduct, as well as weak interactions responsible for enantioselectivity. Such putative interactions include π-stacking and a CH···O electrostatic attraction between the substrate benzyl moiety and the phosphate. Analysis of the computed density functional theory transition structures for the stereodetermining step of the reaction supports the multivariate model obtained. The presented work provides the first comprehensive study of the combined use of CAPT and transition metal catalysis, setting the foundation for future applications.
Total Synthesis and Biological Assessment of Novel Albicidins Discovered by Mass Spectrometric Networking
von Eckardstein, Leonard,Petras, Daniel,Dang, Tam,Cociancich, Stéphane,Sabri, Souhir,Gr?tz, Stefan,Kerwat, Dennis,Seidel, Maria,Pesic, Alexander,Dorrestein, Pieter C.,Royer, Monique,Weston, John B.,Süssmuth, Roderich D.
supporting information, p. 15316 - 15321 (2017/10/20)
Natural products represent an important source of potential novel antimicrobial drug leads. Low production by microorganisms in cell culture often delays the structural elucidation or even prevents a timely discovery. Starting from the anti-Gram-negative antibacterial compound albicidin produced by Xanthomonas albilineans, we describe a bioactivity-guided approach combined with non-targeted tandem mass spectrometry and spectral (molecular) networking for the discovery of novel antimicrobial compounds. We report eight new natural albicidin derivatives, four of which bear a β-methoxy cyanoalanine or β-methoxy asparagine as the central α-amino acid. We present the total synthesis of these albicidins, which facilitated the unambiguous determination of the (2 S,3 R)-stereoconfiguration which is complemented by the assessment of the stereochemistry on antibacterial activity.
1,4-Bis-Dipp/Mes-1,2,4-Triazolylidenes: Carbene Catalysts That Efficiently Overcome Steric Hindrance in the Redox Esterification of α- And β-Substituted α,β-Enals
Yatham, Veera Reddy,Harnying, Wacharee,Kootz, Darius,Neud?rfl, J?rg-M.,Schl?rer, Nils E.,Berkessel, Albrecht
supporting information, p. 2670 - 2677 (2016/03/12)
As reported by Scheidt and Bode in 2005, sterically nonencumbered α,β-enals are readily converted to saturated esters in the presence of alcohols and N-heterocyclic carbene catalysts, e.g., benzimidazolylidenes or triazolylidenes. However, substituents at the α- or β-position of the α,β-enal substrate are typically not tolerated, thus severely limiting the substrate spectrum. On the basis of our earlier mechanistic studies, a set of N-Mes- or N-Dipp-substituted 1,2,4-triazolium salts were synthesized and evaluated as (pre)catalysts in the redox esterification of various α- or β-substituted enals. In particular the 1,4-bis-Mes/Dipp-1,2,4-triazolylidenes overcome the above limitations and efficiently catalyze the redox esterification of a whole series of α/β-substituted enals hitherto not amenable to NHC-catalyzed transformations. The synthetic value of 1,4-bis-Mes/Dipp-1,2,4-triazolylidenes is further demonstrated by the one-step bicyclization of 10-oxocitral to (racemic) nepetalactone in diastereomerically pure form.
Attractive aerobic access to the α,β-unsaturated acyl azolium intermediate: Oxidative NHC catalysis via multistep electron transfer
Ta,Axelsson,Sundén
supporting information, p. 686 - 690 (2016/02/12)
To replace high molecular weight oxidants with air (O2) we introduce multistep electron transfer NHC catalysis. The method provides a general and selective oxidation of the α,β-unsaturated aldehyde derived homoenolate to the synthetically useful α,β-unsaturated acyl azolium intermediate. Several independent oxidative NHC-catalyzed reactions are viable with this strategy and the products can be isolated in high to excellent yields.
AMIDATION METHOD AND ESTERIFICATION METHOD USING SULFONIC ACID HALIDE
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Paragraph 0038, (2017/01/17)
PROBLEM TO BE SOLVED: To provide a safe and economical method for rapidly synthesizing amides and esters in high yield. SOLUTION: There is provided a method for amidating an amine or a derivative thereof using a sulfonic acid halide, where a sulfonic acid halide is allowed to act as an activator on a carboxylic acid or a derivative thereof to synthesize an active ester, and the active ester is reacted with an amine or a derivative thereof as a nucleophile to amidate the amine or the derivative thereof to obtain a corresponding amide or a derivative thereof. In a similar manner, a sulfonic acid halide is allowed to act as an activator on a carboxylic acid or a derivative thereof to synthesize an active ester, and the active ester is reacted with an alcohol or a derivative thereof as a nucleophile to esterify the alcohol or the derivative thereof to obtain a corresponding ester or a derivative thereof. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2016,JPO&INPIT
N,N,N′,N′-Tetramethylenediamine dioxide (TMEDAO2) facilitates atom economical/open atmosphere Ley-Griffith (TPAP) tandem oxidation-Wittig reactions
Read, Christopher D. G.,Moore, Peter W.,Williams, Craig M.
supporting information, p. 4537 - 4540 (2015/09/15)
N,N,N′,N′-Tetramethylethylenediamine dioxide (TMEDAO2) was explored as a more atom economical co-oxidant for the Ley-Griffith oxidation of alcohols to aldehydes. TMEDAO2 was found to selectivity oxidise benzylic and allylic alcohols in comparable yields to that of the standard Ley-Griffith co-oxidant (NMO). Importantly TMEDAO2 facilitated tandem Ley-Griffith-Wittig reactions with stabilised ylides, in good to excellent yields, without the requirement of anhydrous conditions.
Imidazolium ionic liquid-tagged palladium complex: An efficient catalyst for the Heck and Suzuki reactions in aqueous media
Nehra, Pankaj,Khungar, Bharti,Pericherla, Kasiviswanadharaju,Sivasubramanian,Kumar, Anil
, p. 4266 - 4271 (2014/09/29)
An air stable, water soluble, and efficient ionic liquid-tagged Schiff base palladium complex was prepared. The synthesized complex was well characterized by NMR, mass spectrometry, FT-IR, UV-visible spectroscopy and powder X-ray diffraction. The complex was used as a catalyst for the Suzuki and Heck cross-coupling reactions in water. Good to excellent yields were achieved using a modest amount of the catalyst. In addition, the catalyst can be easily reused and recycled for six steps without much loss in activity, exhibiting an example of sustainable and green methodology. the Partner Organisations 2014.
CO/C-H as an acylating reagent: A palladium-catalyzed aerobic oxidative carbonylative esterification of alcohols
Wang, Lu,Wang, Yanxia,Liu, Chao,Lei, Aiwen
supporting information, p. 5657 - 5661 (2014/06/10)
A palladium-catalyzed oxidative carbonylative esterification of a variety of functionalized alcohols under base- and ligand-free conditions has been demonstrated. A CO/olefin combination was utilized as the acylating reagent with O2 as a benign oxidant. Notably, the scope of the substrate alcohols has been greatly broadened. New choice: A palladium-catalyzed oxidative carbonylative esterification of a variety of functionalized alcohols under base- and ligand-free conditions is demonstrated, and a CO/olefin combination is utilized as the acylating reagent with O2 as a benign oxidant. Notably, scope of the substrate alcohols has been greatly broadened.
