121725-20-0Relevant articles and documents
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)
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.
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.
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.
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.
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.
Cooperative N-Heterocyclic Carbene (NHC) and Ruthenium Redox Catalysis: Oxidative Esterification of Aldehydes with Air as the Terminal Oxidant
Zhao, Junfeng,Mueck-Lichtenfeld, Christian,Studer, Armido
supporting information, p. 1098 - 1106 (2013/05/21)
The paper describes a cooperative NHC (N-heterocyclic carbene) and ruthenium-based redox catalysis for the mild aerobic oxidative esterification of various aromatic and heteroaromatic aldehydes. The ruthenium(II) complex Ru(bpz)3(PF6)2 (bpz=2,2′-bipyrazine) as catalyst is shown to be compatible with free NHCs. The NHC is used in these cascade reactions for the umpolung of the aldehyde to form the corresponding Breslow intermediate which in turn gets oxidized to an acylazolium ion by the ruthenium redox catalyst. Air is used as a terminal oxidant for oxidation (regeneration) of the ruthenium catalyst. In addition, we will show that in the absence of the ruthenium redox catalyst and alcohol, NHC-catalyzed aerobic oxidation of aldehydes delivers the corresponding acids in good to excellent yields. Mechanistic studies and DFT calculations supporting our suggested mechanisms are provided. Copyright
NHC-catalyzed C-O or C-N bond formation: Efficient approaches to α,β-unsaturated esters and amides
Zhang, Bo,Feng, Peng,Cui, Yuxin,Jiao, Ning
supporting information; experimental part, p. 7280 - 7282 (2012/07/28)
Simple and efficient NHC-catalyzed transformations of bromoenal or α,β-dibromoenal into α,β-unsaturated esters or amides with high stereoselectivity through C-O or C-N bond formation have been demonstrated. The NHC-catalyzed processes occur under mild con
Organocatalyzed anodic oxidation of aldehydes
Finney, Eric E.,Ogawa, Kelli A.,Boydston, Andrew J.
supporting information; experimental part, p. 12374 - 12377 (2012/09/05)
A method for the catalytic formation of electroauxiliaries and subsequent anodic oxidation has been developed. The process interfaces N-heterocyclic carbene-based organocatalysis with electro-organic synthesis to achieve direct oxidation of catalytically generated electroactive intermediates. We demonstrate the applicability of this method as a one-pot conversion of aldehydes to esters for a broad range of aldehyde and alcohol substrates. Furthermore, the anodic oxidation reactions are very clean, producing only H2 gas as a result of cathodic reduction.
