- A five-step synthesis of (±)-tylophorine via a nitrile-stabilized ammonium ylide
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The Stevens rearrangement of a nitrile-stabilized ammonium ylide is the key step of a very short and practical synthesis of the phenanthroindolizine alkaloid (±)-tylophorine. The method requires only five linear steps and is devoid of any protecting group manipulations.
- Lahm, Guenther,Stoye, Alexander,Opatz, Till
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- NEW SELECTIVE MODULATORS OF INSECT NICOTINIC ACETYLCHOLINE RECEPTORS
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The present invention relates to a compound having the following formula (I): wherein: - A is a (hetero)aryl radical comprising from 5 to 10 carbon atoms, possibly substituted by at least one substituent chosen from the group consisting of: halogen atoms, amino, azido, cyano, nitro, hydroxyl, formyl, carboxyl, amido, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, alkenyl groups, cycloalkenyl groups, and alkynyl groups, and - R is H, CN or CF3, or their pharmaceutically acceptable salts, racemates, diastereomers or enantiomers.
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Page/Page column 18; 19
(2020/06/01)
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- Covalently hooked EOSIN-Y in a Zr(IV) framework as visible-light mediated, heterogeneous photocatalyst for efficient C–H functionalization of tertiary amines
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Herein, we report the synthesis of a novel heterogeneous photo-catalyst by utilizing post-synthetic modification of an amine functionalized Zr(IV) metal-organic framework (UiO-66-NH2) through covalent hooking of EOSIN-Y via dehydrating coupling. The characterization of the catalyst was accomplished by FT-IR, XRD, BET surface analysis, TGA, as well as TEM, SEM, XPS, DRS-UV–visible, and NMR spectroscopy, confirming successful covalent linking of EOSIN-Y with the pendent –NH2 functionality in the framework. That post-modified EY@UiO-66-NH2 acts as simple and green visible light mediated photo-catalyst for the C–H activation of tertiary amines with excellent yields. Importantly, the activity of dye incorporated heterogeneous photo-catalyst is found superior to that for the homogeneous photo-catalyst EOSIN-Y. Thus, separation difficulty of homogeneous catalysis, as well as the environmental adverse effects of toxic EOSIN-Y can be excluded by developing such photo-catalyst. Moreover, EY@UiO-66-NH2 catalyst could be consistently recycled up to 10 cycles, without any significant loss in activity. Based on literature report and experimental findings, we also propose a plausible mechanism for the reaction.
- Kumar, Gaurav,Solanki, Pratik,Nazish, Mohd,Neogi, Subhadip,Kureshy, Rukhsana I.,Khan, Noor-ul H.
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p. 298 - 304
(2019/02/26)
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- Photoredox-Catalyzed Cα-H Cyanation of Unactivated Secondary and Tertiary Aliphatic Amines: Late-Stage Functionalization and Mechanistic Studies
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This paper describes the development and mechanistic studies of a general, high-yielding amine Cα-H cyanation protocol via photoredox catalysis. Inexpensive NaCN is employed as the cyanide source and air is the external oxidant, resulting in mild and highly functional group tolerant conditions. Notably, efficient Cα-H cyanations of secondary and tertiary aliphatic amines and of complex, biologically active compounds (drugs) can be performed using the established methodology. Mechanistic studies suggest that the carboxylic acid additive has three effects: formation of a stabilizing hemiaminal intermediate, prevention of catalyst decomposition by protonating the substrate, and modulation of fluorescence quenching of the photoexcited catalyst species.
- Yilmaz, Ozgur,Oderinde, Martins S.,Emmert, Marion H.
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p. 11089 - 11100
(2018/09/12)
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- Continuous-flow oxidative cyanation of primary and secondary amines using singlet oxygen
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Primary and secondary amines can be rapidly and quantitatively oxidized to the corresponding imines by singlet oxygen. This reactive form of oxygen was produced using a variable-temperature continuous-flow LED-photoreactor with a catalytic amount of tetraphenylporphyrin as the sensitizer. α- Aminonitriles were obtained in good to excellent yields when trimethylsilyl cyanide served as an insitu imine trap. At 25°C, primary amines were found to undergo oxidative coupling prior to cyanide addition and yielded secondary α-aminonitriles. Primary α-aminonitriles were synthesized from the corresponding primary amines for the first time, by an oxidative Strecker reaction at -50 °C. This atom-economic and protecting-group-free pathway provides a route to racemic amino acids, which was exemplified by the synthesis of tert-leucine hydrochloride from neopentylamine. The mild synthesis of imines paves the way to aminonitriles and amino acids. Aerobic oxidation of primary and secondary amines in a continuous photoreactor with singlet oxygen generated insitu led to the rapid formation of imines, which were quantitatively trapped as α-aminonitriles (see scheme; TMS=trimethylsilyl). Benzylic and primary α-aminonitriles, precursors for amino acids, could be efficiently produced in three minutes.
- Ushakov, Dmitry B.,Gilmore, Kerry,Kopetzki, Daniel,McQuade, D. Tyler,Seeberger, Peter H.
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supporting information
p. 557 - 561
(2014/01/23)
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- Cyclization via carbolithiation of α-amino alkyllithium reagents
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(Chemical Equation Presented) We report a new route to tertiary α-amino stereocenters by sequential alkylation of α-amino nitriles followed by reductive lithiation of the nitrile and cycllzation onto an alkene. Reductive lithiation of α-amino nitriles usi
- Bahde, Robert J.,Rychnovsky, Scott D.
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supporting information; experimental part
p. 4017 - 4020
(2009/06/18)
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- Synthesis of 2-Acetyl-1-pyrroline, the Principal Rice Flavor Component
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A new straightforward synthesis of 2-acetyl-1-pyrroline, the principal rice flavor component with a cracker-like flavor, is reported.The reaction sequence involves the conversion of pyrrolidine into tripyrroline, subsequent hydrocyanation of the latter into 2-cyanopyrrolidine, oxidation into 2-cyano-1-pyrroline, and Grignard addition of methylmagnesium iodide, affording an overall yield of 16-19percent from pyrrolidine.In similar way, 2-propionyl-1-pyrroline, a recently discovered flavor component of popcorn, was prepared in addition to several higher analogues, i.e., 2-acyl-1-pyrrolines.Also, the synthesis of 2-(acetyl-d3)-1-pyrroline, a deuterated derivative of the rice flavor compound which is useful for the stable isotope dilution assay, is described.
- Kimpe, Norbert G. De,Stevens, Christian V.,Keppens, Marian A.
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p. 1458 - 1461
(2007/10/02)
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- Process for the preparation of monocyclic, bicyclic and tricyclic aminoacids
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The invention relates to a process for the preparation of compounds of the formula I STR1 in which R represents hydrogen, alkyl or aralkyl, and R1 to R6 denote identical or different radicals hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, cycloalkenylalkyl, aralkyl or aryl, both being monosubstituted, disubstituted or trisubstituted in the aryl moiety by alkyl, alkoxy, hydroxyl, halogen, nitro, methylenedioxy and/or cyano, or in which two of the radicals R1 to R6, together with the carbon atom(s) bearing them form a monocyclic or bicyclic ring system, and the remaining radicals are hydrogen, which process comprises converting, with an oxidizing agent in the presence of a silver salt, a pyrrolidine derivative of the formula II into a Δ1 -pyrroline derivative of the formula III, reacting the latter with hydrogen cyanide or a metal cyanide to form a nitrile of the formula IV, and subjecting the latter to solvolysis with a compound of the formula ROH.
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- OXYDATION OF SECONDARY AMINES TO α-CYANOAMINES
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The dehydrogenation of secondary amines with phenylseleninic anhydride or acid under mild conditions in the presence of either sodium cyanide or trimethylsilylcyanide gives good yields of α-cyanoamines.These compounds can be regarded as protected imines, or as a source of α-amino-acids.
- Barton, Derek H. R.,Billion, Annick,Boivin, Jean
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p. 1229 - 1232
(2007/10/02)
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