924-50-5Relevant articles and documents
Coumarin-related compounds as plant growth inhibitors from two rutaceous plants in Thailand
Jiwajinda, Suratwadee,Santisopasri, Vilai,Ohigashi, Hajime
, p. 420 - 423 (2000)
Chemical investigation of naturally occurring plant growth inhibitors from Rutaceous plants in Thailand led us to identify five 7-methoxycoumarins and one 5,7-dimethoxycoumarin from Murraya paniculata, and six furanocoumarins from Citrus aurantifolia. Of these compounds, murranganon senecioate (1) is a new natural compound found in M. paniculata. Minumicrolin (6) was found to be highly active against the 2nd leaf sheath elongation of rice seedlings.
Effect of Differential Geminal Substitution of γAmino Acid Residues at the (i + 2) Position of αγTurn Segments on the Conformation of Template β-Hairpin Peptides
Chatterjee, Sunanda,Debnath, Swapna,Ghosh, Suvankar,Pandit, Gopal,Satpati, Priyadarshi
supporting information, p. 11310 - 11323 (2021/09/07)
The effect of insertion of three geminally dimethyl substituted γamino acid residues [γ2,2 (4-amino-2,2-dimethylbutanoic acid), γ3,3 (4-amino-3,3-dimethylbutanoic acid), and γ4,4 (4-amino-4,4-dimethylbutanoic acid)] at the (i + 2) position of a two-residue αγC12 turn segment in a model octapeptide sequence Leu-Phe-Val-Aib-Xxx-Leu-Phe-Val (where Xxx = γamino acid residues) has been investigated in this study. Solution conformational studies (NMR, CD, and IR) and ab initio calculations indicated that γ3,3 and γ4,4 residues were well accommodated in the β-hairpin nucleating αγC12 turns, which gave rise to well-registered hairpins, in contrast to γ2,2, which was unable to form a tight C12 β-hairpin nucleating turn and promote a well-registered β-hairpin. Geminal disubstitution at the Cα carbon in γ2,2 led to unfavorable steric contacts, disabling its accommodation in the αγC12 hairpin nucleating turn unlike the γ3,3 and γ4,4 residues. Geminal substitutions at different carbons along the backbone constrained backbone torsion angles for the three γamino acid residues differently, generating diverse conformational preferences in them. Folded hairpins were energetically more stable (～8 to 9 kcal/mol) than the unfolded peptides. Conformational preference of the peptides was independent of the N-terminal protecting group. Such fundamental understanding will instrumentalize the future directed design of foldamers.
N-Heterocyclic Carbene/Carboxylic Acid Co-Catalysis Enables Oxidative Esterification of Demanding Aldehydes/Enals, at Low Catalyst Loading
Berkessel, Albrecht,Biswas, Animesh,Harnying, Wacharee,Sudkaow, Panyapon
supporting information, p. 19631 - 19636 (2021/08/09)
We report the discovery that simple carboxylic acids, such as benzoic acid, boost the activity of N-heterocyclic carbene (NHC) catalysts in the oxidative esterification of aldehydes. A simple and efficient protocol for the transformation of a wide range of sterically hindered α- and β-substituted aliphatic aldehydes/enals, catalyzed by a novel and readily accessible N-Mes-/N-2,4,6-trichlorophenyl 1,2,4-triazolium salt, and benzoic acid as co-catalyst, was developed. A whole series of α/β-substituted aliphatic aldehydes/enals hitherto not amenable to NHC-catalyzed esterification could be reacted at typical catalyst loadings of 0.02–1.0 mol %. For benzaldehyde, even 0.005 mol % of NHC catalyst proved sufficient: the lowest value ever achieved in NHC catalysis. Preliminary studies point to carboxylic acid-induced acceleration of acyl transfer from azolium enolate intermediates as the mechanistic basis of the observed effect.
Engineering Catalysts for Selective Ester Hydrogenation
Dub, Pavel A.,Batrice, Rami J.,Gordon, John C.,Scott, Brian L.,Minko, Yury,Schmidt, Jurgen G.,Williams, Robert F.
, p. 415 - 442 (2020/03/04)
The development of efficient catalysts and processes for synthesizing functionalized (olefinic and/or chiral) primary alcohols and fluoral hemiacetals is currently needed. These are valuable building blocks for pharmaceuticals, agrochemicals, perfumes, and so forth. From an economic standpoint, bench-stable Takasago Int. Corp.'s Ru-PNP, more commonly known as Ru-MACHO, and Gusev's Ru-SNS complexes are arguably the most appealing molecular catalysts to access primary alcohols from esters and H2 (Waser, M. et al. Org. Proc. Res. Dev. 2018, 22, 862). This work introduces economically competitive Ru-SNP(O)z complexes (z = 0, 1), which combine key structural elements of both of these catalysts. In particular, the incorporation of SNP heteroatoms into the ligand skeleton was found to be crucial for the design of a more product-selective catalyst in the synthesis of fluoral hemiacetals under kinetically controlled conditions. Based on experimental observations and computational analysis, this paper further extends the current state-of-the-art understanding of the accelerative role of KO-t-C4H9 in ester hydrogenation. It attempts to explain why a maximum turnover is seen to occur starting at 25 mol % base, in contrast to only 10 mol % with ketones as substrates.
Direct and Tandem Routes for the Copolymerization of Ethylene with Polar Functionalized Internal Olefins
Chen, Min,Chen, Changle
supporting information, p. 1206 - 1210 (2019/12/24)
Transition metal catalyzed ethylene copolymerization with polar monomers is a highly challenging reaction. After decades of research, the scope of suitable comonomer substrates has expanded from special to fundamental polar monomers and, recently, to 1,1-disubstituted ethylenes. Described in this contribution is a direct and tandem strategy to realize ethylene copolymerization with various 1,2-disubstituted ethylenes. The direct route is sensitive to sterics of both the comonomers and the catalyst. In the tandem route, ruthenium-catalyzed ethenolysis can convert 1,2-disubstituted ethylenes into terminal olefins, which can be subsequently copolymerized with ethylene to afford polar functionalized polyolefins. The one-pot, two-step tandem route is highly versatile and efficient in dealing with challenging substrates. This work is a step forward in terms of expanding the substrate scope for transition metal catalyzed ethylene copolymerization with polar-functionalized comonomers.
Cyanide-Free One-Pot Synthesis of Methacrylic Esters from Acetone
Koyama, Minoru,Kawakami, Takafumi,Okazoe, Takashi,Nozaki, Kyoko
, p. 10913 - 10917 (2019/08/02)
Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF3CH2, and n-C6F13CH2CH2 esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C6F13CH2CH2 esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d6 and MeOH-d4, with DBU in acetonitrile afforded deuterated MMA (MMA-d8) in 70 % yield.
Synthesis method of methyl senecioate
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Paragraph 0007; 0009-0017; 0028, (2018/10/19)
The invention discloses a synthesis method of methyl senecioate. The synthesis method takes 1,3-propane sultone, methylimidazole, senecioic acid, methanol, aluminum hydroxide powder, citric acid, nickel nitrate and ammonium metatungstate as main raw materials; a synthesis technology provided by the invention takes senecioic acid and methanol to be subjected to esterification reaction under the action of a catalyst NiW/Al-CA to obtain methyl senecioate; in a preparation process of the catalyst, citric acid is added and used as organic acid to weaken a mutual effect between a metal component anda carrier; when the quantity of carboxyl groups of an organic acid molecule is greater, the mutual effect between active metal and the carrier is more obvious; compared with a traditional synthesis method, the synthesis method has the advantages that the catalyst is easy to separate and recycle and the environment pollution is reduced; a target product is synthesized in one step, side reaction isreduced and post-treatment steps are simplified; the yield of products is greatly improved.
Synthesis method of ciclopirox olamine
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Paragraph 0050; 0051, (2017/12/29)
The invention discloses a synthesis method of ciclopirox olamine. The synthesis method includes following steps: (1), preparing dimethyl methacrylate; (2), preparing cyclohexane formyl chloride; (3), preparing 5-oxo-3-methyl-5-cyclohexyl-3-methyl pentenoate; (4), preparing 1-hydroxy-4-methyl-6-cyclohexyl-2(1H)-pyridone; (5), preparing 1-hydroxy-4-methyl-6-cyclohexyl-2(1H)-pyridone-2-amino-ethylate ciclopirox olamine. The synthesis method has the advantages of high yield, high product quality, low running cost, automatic running of equipment, high stability and easiness in meeting industrial needs.
DMAP-Catalyzed [4 + 2] Cycloaddition of α,β-Unsaturated Carboxylic Acids with Ketones for Synthesis of α,β-Unsaturated δ-Lactones
Jin, Jinghai,Xu, Qinchang,Deng, Weiping
supporting information, p. 397 - 400 (2017/04/27)
The DMAP-catalyzed [4 + 2] cycloaddition of α,β-unsaturated carboxylic acids with ketones furnishing α,β-unsaturated δ-lactones in good yields (up to 80%) is described, which is the first example of remote γ-C(sp3)-H activation of α,β-unsaturated carboxylic acids facilitated by DMAP, a pyridine-based catalyst. Copyright
Mukaiyama aldol reactions catalyzed by a trimeric organo aluminum(III) alkoxide
Kim, So Han,Yoon, Sungwoo,Kim, Youngjo,Verkade, John G.
, p. 1193 - 1206 (2014/09/30)
Mukaiyama aldol reactions of enol ethers with a variety of aldehydes and ketones are efficiently catalyzed at 0-25 °C by the sterically bulky trimeric organo aluminum(III) alkoxide 1 synthesized via the reaction of 3 equiv of AlMe3 with tripodal tris(2-hydroxy-3-tert-butyl-5-methylphenyl) methane and the elimination of 3 equiv of methane. Comparisons of its catalytic properties with the less sterically hindered analogue 2, the more sterically hindered analogue 3, a monomeric aluminum near-analogue 4, and a dimeric alumatrane 5 revealed that 1 possesses superior activity.
