- Muricatisine - A new alkaloid from two species of Oxytropis
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The new alkaloid muricatisine has been isolated from the epigeal parts of the plants Oxytropis muricata (Pall.) DC. (Mongolia) and O. puberula Boriss. (Kazakhstan), which belong to the Fabaceae family, and its structure has been established on the basis of spectral characteristics as N-benzoyl-2-oxo-2-phenylethylamine and has been confirmed by a partial synthesis.
- Demeuov,Akhmedzhanova,Moldagulov,Shakirov
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- Synthesis method of alpha-acylamino ketone compound
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The invention discloses a synthesis method of an alpha-acylamino ketone compound, and belongs to the technical field of organic synthesis. The preparation method comprises the following steps: mixingan alkenyl azide compound 1, a carboxylic acid compound 2 and an organic solvent, and heating to react to obtain the alpha-acylamino ketone compound 3. Compared with the prior art, the method has thefollowing advantages: (1) the synthesis process is simple and efficient, no catalyst is needed in the whole process, and the alpha-acylamino ketone compound can be obtained with high yield by dissolving the alkenyl azide compound and the carboxylic acid compound in the solvent and stirring; (2) raw materials are cheap and easy to obtain, reaction conditions are mild, and operation is simple; (3) the substrate is wide in application range and can be used for modifying drug molecules; and (4) the atom economy is high, and the requirements of green chemistry are met.
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Paragraph 0020-0026; 0027-0029
(2020/12/08)
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- Synthesis of α-Amidoketones through the Cascade Reaction of Carboxylic Acids with Vinyl Azides under Catalyst-Free Conditions
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An efficient synthesis of α-amidoketone derivatives through the cascade reactions of carboxylic acids with vinyl azides is presented. Compared with literature protocols, notable features of this new method include catalyst-free conditions, broad substrate scope, good tolerance of a wide range of functional groups, and high efficiency. In addition, the synthetic potential of this method as a tool for late-stage modification was convincingly manifested by its application in the structural elaborations of a number of carboxylic acid drug molecules.
- Gao, Cai,Zhou, Qianting,Yang, Li,Zhang, Xinying,Fan, Xuesen
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p. 13710 - 13720
(2020/11/13)
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- Site-Selective Conversion of Azido Groups at Carbonyl α-Positions to Diazo Groups in Diazido and Triazido Compounds
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This paper reports on the selective conversion of alkyl azido groups at the carbonyl α-position to diazo compounds. Through β-elimination of dinitrogen, followed by hydrazone formation/decomposition, α-azidocarbonyl moieties were transformed into α-diazo carbonyl groups in one step. As these reaction conditions do not involve aryl or general alkyl azides, site-selective conversions of di- and triazides were achieved. Through this method, the successive site-selective conjugation of the triazido molecule with three different components is demonstrated.
- Yokoi, Taiki,Tanimoto, Hiroki,Ueda, Tomomi,Morimoto, Tsumoru,Kakiuchi, Kiyomi
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p. 12103 - 12121
(2018/10/09)
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- Remote C(sp3)-H Oxygenation of Protonated Aliphatic Amines with Potassium Persulfate
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This letter describes the development of a method for selective remote C(sp3)-H oxygenation of protonated aliphatic amines using aqueous potassium persulfate. Protonation serves to deactivate the proximal C(sp3)-H bonds of the amine substrates and also renders the amines soluble in the aqueous medium. These reactions proceed under relatively mild conditions (within 2 h at 80 °C with amine as limiting reagent) and do not require a transition metal catalyst. This method is applicable to a variety of types of C(sp3)-H bonds, including 3°, 2°, and benzylic C-H sites in primary, secondary, and tertiary amine substrates.
- Lee, Melissa,Sanford, Melanie S.
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p. 572 - 575
(2017/02/10)
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- 2,5-diphenyl-oxazole preparation method
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The invention relates to a method for preparing scintillation pure grade 2,5-diphenyl oxazole (DPO or PPO for short). The method comprises the following steps: by taking benzoyl glycine as a raw material, performing multiple steps of reaction such as acylating chlorination, Frieldel-Crafts and ring formation, purifying middle products of each step without being separated, and preparing 2,5-diphenyl oxazole by using a one-pot method. An obtained product can be rectified and purified, the requirements of a scintillator cannot be met but metal oxide heating treatment is needed, and thus a 2,5-diphenyl oxazole product for scintillation fluor can be obtained. As the one-pot method is adopted to prepare 2,5-diphenyl oxazole, the reaction steps are reduced, the operation process is simplified, the production efficiency is improved, a purification method is simple, convenient and effective, and on-scale industrialization production is achieved.
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Paragraph 0026; 0027; 0036; 0038
(2019/02/04)
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- Synthesis of Multiple-Substituted Pyrroles via Gold(I)-Catalyzed Hydroamination/Cyclization Cascade
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A gold-catalyzed cascade hydroamination/cyclization reaction of α-amino ketones with alkynes to form substituted pyrroles has been developed. The method offers several advantages such as high regioselectivity with the tested cases, wide functional group tolerance, and easily accessible starting materials. The synthetic utility of the obtained pyrrole products was demonstrated by their efficient transformations to 2-vinylated pyrroles via gold-catalyzed intermolecular hydroarylation.
- Li, Xiangdong,Chen, Ming,Xie, Xin,Sun, Ning,Li, Shi,Liu, Yuanhong
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supporting information
p. 2984 - 2987
(2015/06/30)
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- Base-catalyzed N -N bond cleavage of hydrazones: Synthesis of α-amino ketones
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An efficient Cs2CO3-promoted synthesis of α-amino ketones using hydrazines, aldehydes, and α-haloketones as starting materials through a cascade condensation/nucleophilic substitution/N -N bond cleavage route is developed. The carbonyl group plays a key role in this novel N -N bond cleavage process. Breaking good: A novel method of base-catalyzed N -N bond cleavage of hydrazones has been discovered. A variety of α-amino ketones was synthesized using hydrazines, α-haloketones, and benzaldehyde as starting materials through a cascade condensation/ nucleophilic substitution/N -N bond cleavage sequence.
- Tang, Hai-Tao,Zhou, Yun-Bing,Zhu, Yu,Sun, Hong-Chao,Lin, Min,Zhan, Zhuang-Ping
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supporting information
p. 1278 - 1281
(2014/05/06)
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- Synthesis of novel trisubstituted imidazolines
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Imidazolines substituted at the 1- and either the 4-, or 5-position with phenyl and at the 2-position with alkyl or phenyl have been prepared in racemic form. They appear to be fairly stable compounds and potentially useful as scaffolds in medicinal chemistry. Georg Thieme Verlag Stuttgart.
- Lakner, Frederick J.,Parker, Matthew A.,Rogovoy, Boris,Khvat, Alexander,Ivachtchenko, Alexander
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experimental part
p. 1987 - 1990
(2009/12/25)
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- Competition between α-cleavage and energy transfer in α-azidoacetophenones
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(Chemical Equation Presented) Molecular modeling demonstrates that the first excited state of the triplet ketone (T1K) in azide 1b has a (π,π*) configuration with an energy that is 66 kcal/mol above its ground state and its second excited state (T2K) is 10 kcal/mol higher in energy and has a (n,π*) configuration. In comparison, T 1K and T2K of azide 1a are almost degenerate at 74 and 77 kcal/mol above the ground state with a (n,π*) and (π,π*) configuration, respectively. Laser flash photolysis (308 nm) of azide 1b in methanol yields a transient absorption (λmax = 450 nm) due to formation of T1K, which decays with a rate of 2.1 × 10 -5 s-1 to form triplet alkylnitrene 2b (λmax = 320 nm). The lifetime of nitrene 2b was measured to be 16 ms. In contrast, laser flash photolysis (308 nm) of azide 1a produced transient absorption spectra due to formation of nitrene 2a (λ max = 320 nm) and benzoyl radical 3a (λmax = 370 nm). The decay of 3a is 2 × 10-5 s-1 in methanol, whereas nitrene 2a decays with a rate of ～91 s-1. Thus, T 1K (π,π*) in azide 1b leads to energy transfer to form nitrene 2b; however, α-cleavage is not observed since the energy of T 2K (n,π*) is 10 kcal/mol higher in energy than T 1K, and therefore, T2K is not populated. In azide 1a both α-cleavage and energy transfer are observed from T1K (n,π*) and T2K (π,π*), respectively, since these triplet states are almost degenerate. Photolysis of azide 1a yields mainly product 4, which must arise from recombination of benzoyl radicals 3a with nitrenes 2a. However, products studies for azide 1b also yield 4b as the major product, even though laser flash photolysis of azide 1b does not indicate formation of benzoyl radical 3b. Thus, we hypothesize that benzoyl radicals 3 can also be formed from nitrenes 2. More specifically, nitrene 2 does undergo α-photocleavage to form benzoyl radicals and iminyl radicals. The secondary photolysis of nitrenes 2 is further supported with molecular modeling and product studies.
- Muthukrishnan, Sivaramakrishnan,Mandel, Sarah M.,Hackett, John C.,Singh, Pradeep N. D.,Hadad, Christopher M.,Krause, Jeanette A.,Gudmundsdottir, Anna D.
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p. 2757 - 2768
(2008/02/02)
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- Microbial deracemisation of N-(1-hydroxy-1-phenylethyl)benzamide
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Microbial deracemisation of racemic N-(1-hydroxy-1-phenylethyl)benzamide to give the (R)-enantiomer is described using whole cells of Cunninghamella echinulata NRRL 1384. The deracemisation involves fast highly (S)-selective oxidation followed by slower p
- Cardus, Gareth J.,Carnell, Andrew J.,Trauthwein, Harald,Riermeir, Thomas
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p. 239 - 243
(2007/10/03)
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- Chemistry and biology of diazonamide A: Second total synthesis and biological investigations
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As an especially unique target for chemical synthesis, diazonamide A has the potential to be constructed through a plethora of synthetic routes, each attended by different challenges and opportunities for discovery. In this article, we detail our second total synthesis of diazonamide A through a sequence entirely distinct from that employed in our first campaign, one whose success required the development of several special strategies and tactics. We also disclose our complete studies regarding the chemical biology of diazonamide A and its structural congeners, and more fully delineate the scope of our protocol for Robinson-Gabriel cyclodehydration using pyridine-buffered POCl 3.
- Nicolaou,Hao, Junliang,Reddy, Mali V.,Rao, Paraselli Bheema,Rassias, Gerasimos,Snyder, Scott A.,Huang, Xianhai,Chen, David Y.-K.,Brenzovich, William E.,Giuseppone, Nicolas,Giannakakou, Paraskevi,O'Brate, Aurora
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p. 12897 - 12906
(2007/10/03)
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- Synthetic applicability and in situ recycling of a B-methoxy oxazaborolidine catalyst derived from cis-1-amino-indan-2-ol
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A procedure is described that greatly simplifies the use of an oxazaborolidine catalyst derived from (1R,2S) cis-1-amino-indan-2-ol. This B-OMe catalyst has been employed in the asymmetric reduction of a number of structurally diverse prochiral ketones, in particular the reduction of α-amino acetophenone and its derivatives. A method for reducing the effective catalyst loading by "in situ recycling" is also presented.
- Gilmore, Nathan J.,Jones, Simon,Muldowney, Mark P.
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p. 2805 - 2808
(2007/10/03)
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- Photolysis of α-azidoacetophenones: Direct detection of triplet alkyl nitrenes in solution
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We report the first detection of triplet alkyl nitrenes in fluid solution by laser flash photolysis of α-azido acetophenone derivatives, 1. Azides 1 contain an intramolecular triplet sensitizer, which ensures formation of the triplet alkyl nitrene by bypassing the singlet nitrene intermediate. At room temperature, azides 1 cleave to form benzoyl and methyl azide radicals in competition with triplet energy transfer to form triplet alkyl nitrene. The major photoproduct 3 arises from interception of the triplet alkyl nitrene with benzoyl radicals. The triplet alkyl nitrene intermediates are also trapped with molecular oxygen to yield the corresponding 2-nitrophenylethanone. Laser flash photolysis of 1 reveals that the triplet alkyl nitrenes have absorption around 300 nm. The triplet alkyl nitrenes were further characterized by obtaining their UV and IR spectra in argon matrices. 13C and 15N isotope labeling studies allowed us to characterize the C-N stretch of the nitrene intermediate at 1201 cm-1.
- Singh, Pradeep N. D.,Mandel, Sarah M.,Robinson, Rachel M.,Zhu, Zhendong,Franz, Roberto,Ault, Bruce S.,Gudmundsdottir, Anna D.
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p. 7951 - 7960
(2007/10/03)
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- Fischer synthesis of 3-(N-acylamino)-2-phenylindoles
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Phenylhydrazones were obtained by the reaction of phenylhydrazine with ω-(N-acylamino)-acetophenones and were converted into 3-(N-acylamino)indoles by the Fischer cyclizaction.
- Przheval'Skii,Skvortsova,Magedov
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p. 1055 - 1061
(2007/10/03)
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- Photolysis of α-azidoacetophenones: Trapping of triplet alkyl nitrenes in solution
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(Matrix presented) Selective excitation of the ketone chromophore in α-azidoacetophenones, 1, leads to intramolecular triplet energy transfer to the azido group, which forms the corresponding triplet alkyl nitrene, 2. Azides 1 also undergo α-cleavage to form benzoyl and methyl azido radicals in competition with nitrene formation. Thus the major photoproduct, 2-benzoylamino-1-phenylethanone, 3, comes from trapping of 2 with a benzoyl radical. This appears to be the first observation of bimolecular trapping of triplet alkyl nitrenes in solution.
- Mandel, Sarah M.,Bauer, Jeanette A. Krause,Gudmundsdottir, Anna D.
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p. 523 - 526
(2007/10/03)
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- Pyrrolomorphinans as δ opioid receptor antagonists. The role of steric hindrance in conferring selectivity
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A series of 2',3'-disubstituted pyrrolomorphinans (5a-i) were synthesized to determine the role of steric hindrance at μ and γ receptors in promoting δ opioid receptor antagonist selectivity. In smooth muscle preparations, five members of the series (5a-c,e,f) possessed K(e) values in the range 2-15 nM and were 6 selective. Since the unsubstituted analogue 4 possessed δ antagonist potency of similar magnitude, but was not δ selective, it is suggested that the 2',3'substitution confers δ selectivity by hindering the interaction of the pharmacophore at μ and γ receptors, while not affecting δ receptors.
- Farouz-Grant,Portoghese
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p. 1977 - 1981
(2007/10/03)
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- Investigations of Novel Azomethine Ylide-Forming Photoreactions of N-Silylmethylimides
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The scope of a recently discovered (Yoon, E.C. et al.J.Am.Chem.Soc. 1995, 117, 2698), azomethine ylide-forming photoreaction has been explored by probing the excited state chemistry of several N-trimethylsilylmethyl substituted cyclic and acyclic imides and amide analogs.Photolysis of N-maleimide (4) in acetonitrile leads to efficient production of the tricyclic product 16, formed by trapping of the photogenerated azomethine ylide intermediate 15 through cycloaddition with 4.Irradiation 4 in solutions containing high concentrations of the dipolarophiles, acrylonitrile or fumaronitrile, results in production of the products (19-21 and 23-24, respectively) arising by cycloaddition of the ylide 15 with the added dipolarophiles.In contrast, photolysis of the nonconjugated cyclic imide, N-succinimide (5), brings about N-acyl migration resulting in the exclusive production of the unstable, iminolactone 30.On the other band, acyclic, N-trimethylsilylmethyl aroyl imides 6-8 undergo the excited state C to O silyl migration reaction to produce azomethine ylide intermediates 35.Both in the presence or absence of added dipolarophiles, these ylides undergo electrocyclization to form transient aziridine intermediates 36 which react further by ring opening to generate N-phenacylamide products 32-34.In contrast, the nonconjugated imide, N--N-acetylacetamide (9), is unreactive upon irradiation.Similarly, simple N-amides 10-13, while being photochemically labile, do not react to form "trappable" ylide intermediates upon irradiation.The results outlined above are presented and discussed in terms of the scope and limitations of the new, azomethine ylide-forming photoreaction of silylmethyl imides.
- Yoon, Ung Chan,Cho, Sung Ju,Lee, Yean-Jang,Mancheno, Maria J.,Mariano, Patrick S.
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p. 2353 - 2360
(2007/10/02)
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- Baker's Yeast Reduction of α-(Acylamino)acetophenones and Lipase Catalyzed Resolution of 2-Acylamino-1-arylethanols
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Enzymatic reduction of α-acylaminoacetophenones with fermenting baker's yeast afforded optically active (R)-2-acylamino-1-arylethanols.Furthermore, lipase-catalyzed resolution of the 2-acylamino-1-arylethanols using vinyl acetate as an acyl donor resulted in the formation of (S)-1-acetoxy-2-acylamino-1-arylethanols and (R)-2-acylamino-1-arylethanols.
- Izumi, Taeko,Fukaya, Katsumi
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p. 1216 - 1221
(2007/10/02)
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- Studies on organophosphorus compounds 55. A new and facile synthetic route to 1-alkyl(aryl)-2-amino-1-hydroxyalkylphosphonic acids
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Nucleophilic addition of dimethyl phosphite to acylamino ketones prepared conveniently by the Dakin-West reaction involving reaction of the corresponding α-amino acids and acid anhydrides, followed by subsequent hydrolysis affords 1-alkyl(aryl)-2-amino-1-hydroxyalkylphosphonic acids in satisfactory yield.
- Yuan,Chen
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p. 531 - 532
(2007/10/02)
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- Synthesis and hypolipidemic activities of 5-thienyl-4-oxazoleacetic acid derivatives
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A series of 2,5-disubstituted 4-oxazoleacetic acid derivatives was synthesized and evaluated for hypolipidemic activity. Among them, those with a thienyl group at C-5 of the oxazole ring exerted highly potent hypolipidemic effects in rats. 2-(4-Fluorophen
- Moriya,Takabe,Maeda,Matsumoto,Takashima,Takeyama
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p. 333 - 341
(2007/10/02)
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