- Berberis alkaloids XXXIX. New alkaloids from B. densiflora
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The alkaloid composition of the leaves of Berberis densiflora has been studied. Berberine, β-allocryptopine, oxyacanthine, glautine, thalicmidine, isocorydine, O-methylcorypalline and the new bases densinine and densiberine have been isolated. The structures of the new alkaloids have been established by a study of spectral characteristics and chemical transformations. This is the first time that any of the known alkaloids, apart from berberine, have been isolated from a plant of this species and it is the first time that β-allocryptopine and O-methylcorypalline have been isolated from the Berberis genus.
- Khamidov,Aripova,Telezhenetskaya,Karimov,Dzhenberov
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- Total Synthesis of (-)-Oxycodone via Anodic Aryl-Aryl Coupling
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A fully regio- and diastereoselective electrochemical 4a-2′-coupling of a 3′,4′,5′-trioxygenated laudanosine derivative enables the synthesis of the corresponding morphinandienone. This key intermediate is further transformed into (-)-oxycodone through conjugate nucleophilic substitution for E-ring closure and [4 + 2] cycloaddition with photogenerated singlet oxygen to accomplish diastereoselective hydroxylation at C-14. The anodic transformation provides high yields and can be performed under constant current conditions both in a simple undivided cell or in continuous flow.
- Lipp, Alexander,Selt, Maximilian,Ferenc, Dorota,Schollmeyer, Dieter,Waldvogel, Siegfried R.,Opatz, Till
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supporting information
p. 1828 - 1831
(2019/03/07)
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- Total Synthesis of Tetrahydroisoquinoline-Based Bioactive Natural Products Laudanosine, Romneine, Glaucine, Dicentrine, and Their Unnatural Analogues Isolaudanosine and Isoromneine
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Starting from suitably substituted homophthalic acids, total synthesis of titled alkaloids have been demonstrated in very good yields. The obtained natural products laudanosine and romneine were utilized to accomplish synthesis of two isoquinoline-based alkaloids glaucine and dicentrine. Base-induced selective generation of two different types of benzylic carbanions, their coupling reactions with 3,4-dimethoxybenzyl mesylate, and the regioselective iodination followed by intramolecular aryl-aryl coupling reactions to form the fused biaryl systems were the strategic steps.
- Jangir, Ravi,Argade, Narshinha P.
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p. 1655 - 1663
(2017/03/21)
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- Light-Induced Alkylation of (Hetero)aromatic Nitriles in a Transition-Metal-Free C-C-Bond Metathesis
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A light-induced C-C-σ-bond metathesis was achieved through transition-metal-free activation of an unstrained C(sp3)-C(sp3)-σ-bond in 1-benzyl-1,2,3,4-tetrahydroisoquinolines. A photoredox-mediated single-electron oxidation of these precursor amines yield radical cations which undergo a homolytic cleavage of a C(sp3)-C(sp3)-σ-bond rather than the well-known α-C-H-scission. The resulting carbon-centered radicals are used in the ipso-substitution of (hetero)aromatic nitriles proceeding through another single-electron transfer-mediated C-C-bond cleavage and formation.
- Lipp, Benjamin,Lipp, Alexander,Detert, Heiner,Opatz, Till
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supporting information
p. 2054 - 2057
(2017/04/27)
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- Synthesis of 1-substituted tetrahydroisoquinolines by lithiation and electrophilic quenching guided by in situ IR and NMR spectroscopy and application to the synthesis of salsolidine, carnegine and laudanosine
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The lithiation of N-tert-butoxycarbonyl (N-Boc)-1,2,3,4- tetrahydroisoquinoline was optimized by in situ IR (ReactIR) spectroscopy. Optimum conditions were found by using n-butyllithium in THF at -50 °C for less than 5 min. The intermediate organolithium was quenched with electrophiles to give 1-substituted 1,2,3,4-tetrahydroisoquinolines. Monitoring the lithiation by IR or NMR spectroscopy showed that one rotamer reacts quickly and the barrier to rotation of the Boc group was determined by variable-temperature NMR spectroscopy and found to be about 60.8 kJ mol-1, equating to a half-life for rotation of approximately 30 s at -50 °C. The use of (-)-sparteine as a ligand led to low levels of enantioselectivity after electrophilic quenching and the "poor man's Hoffmann test" indicated that the organolithium was configurationally unstable. The chemistry was applied to N-Boc-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline and led to the efficient synthesis of the racemic alkaloids salsolidine, carnegine, norlaudanosine and laudanosine. Copyright
- Li, Xiabing,Leonori, Daniele,Sheikh, Nadeem S.,Coldham, Iain
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p. 7724 - 7730
(2013/07/19)
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- Synthesis of alkaloids by stevens rearrangement of nitrile-stabilized ammonium ylides: (±)-laudanosine, (±)-laudanidine, (±)-armepavine, (±)-7-methoxycryptopleurine, and (±)-xylopinine
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The Stevens rearrangement of nitrile-stabilized ammonium ylides in conjunction with the reductive removal of the nitrile function permits the facile construction of α-branched amines from α-aminonitriles. We employed this reaction sequence for the preparation of (±)-laudanosine, (±)-laudanidine and (±)-armepavine, (±)-7- methoxycryptopleurine, and (±)-xylopinine from two closely related and readily accessible bicyclic α-aminonitriles. The final products were obtained in high to almost quantitative yields (71-98%) from the quaternary ammonium salts obtained by N-alkylation of these starting materials.
- Orejarena Pacheco, Julio Cesar,Lahm, Günther,Opatz, Till
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p. 4985 - 4992
(2013/06/27)
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- A variation of the Pictet-Spengler reaction via a sequential reduction-cyclization reaction of N-acylcarbamates: synthesis of 1-substituted tetrahydroisoquinoline derivatives
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A new variation of the Pictet-Spengler reaction for the synthesis of 1-substituted tetrahydroisoquinoline derivatives has been developed. The reaction employs the reduction of N-acylcarbamates by DIBAL-H followed by simultaneous cyclization mediated by BF3·OEt2. The synthetic potential of this method has been illustrated by the synthesis of the tetrahydroisoquinoline alkaloids, (±)-xylopinine, (±)-laudanosine, (±)-8-oxo-O-methylbharatamine, and (±)-isoindoloisoquinolone.
- Kuhakarn, Chutima,Panyachariwat, Nattakan,Ruchirawat, Somsak
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p. 8182 - 8184
(2008/03/14)
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- Potential cancer chemopreventive activity of simple isoquinolines, 1-benzylisoquinolines, and protoberberines
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Seventeen simple isoquinolines, 15 1-benzylisoquinolines, and 19 protoberberines were tested for their inhibitory activities against Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol- 13-acetate (TPA) in Raji cells. Among the tested alkaloids, the inhibitory activity of all 1-benzylisoquinolines and 11 protoberberines was higher than that of β-carotene. The 1-benzylisoquinolines 19, 21, 22, 29, and 34 and protoberberines 41, 47-49, 51, 52, and 55 showed potent inhibitory effects on EBV-EA induction (96-100% inhibition at 1 × 103 mol ratio/TPA). These alkaloids were more active than the naturally occurring alkaloids, 23, 25, 33, 53, and 54. In addition, fifteen simple isoquinolines, eighteen 1-benzylisoquinolines and eight protoberberines were evaluated with respect to their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. Nine simple isoquinolines, ten 1-benzylisoquinolines, and four protoberberines were more potent than α-tocopherol, and four 1-benzylisoquinolines, 20 and 28-30, exhibited potent activities (SC50 4.5-5.8 μM). Their activities were higher than the naturally occurring alkaloids, 23, 25, and 33. Therefore, some of the isoquinoline alkaloids indicating the high activity on both assays may be potentially valuable cancer chemopreventive agents. Structure-activity relationships are discussed for both tests.
- Cui, Wenhua,Iwasa, Kinuko,Tokuda, Harukuni,Kashihara, Akiko,Mitani, Yosuke,Hasegawa, Tomoko,Nishiyama, Yumi,Moriyasu, Masataka,Nishino, Hoyoku,Hanaoka, Miyoji,Mukai, Chisato,Takeda, Kazuyoshi
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- A convenient synthesis of 1-benzyl-1,2,3,4-tetrahydroisoquinolines by combined Strecker/Bruylants reaction
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Strecker reaction of iodophenethylamines with phenylacetaldehydes afforded the corresponding α-aminonitriles, which on treatment with i-propyl magnesium chloride underwent a Bruylants reaction to give the title compounds. Their structures were deduced by NMR and by an independent preparation starting from papaverine. The educts were easily available by standard procedures. Springer-Verlag 2004.
- Reimann, Eberhard,Ettmayr, Christian
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p. 1289 - 1295
(2007/10/03)
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- Syntheses of the seco benzyltetrahydroisoquinoline alkaloids polysignine and methoxypolysignine
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The structures previously assigned to the seco benzyltetrahydroisoquinoline alkaloids polysignine (1) and methoxypolysignine (2) have been confirmed by total syntheses in which the key step involved cleavage of the C 1-N bonds in the corresponding N-methylbenzyltetrahydroisoquinolines. CSIRO 2000.
- Nimgirawath, Surachai
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p. 523 - 525
(2007/10/03)
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- A new regioselective synthesis of isopavine and pavine alkaloids via double cyclization of N-(1,2-diarylethyl)-N-(2-phenylsulfinylethyl)formamide
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Pummerer reaction of N-[1,2-(3,4-dimethoxyphenyl)ethyl]-N-(2-phenylsulfinylethyl)formamide (9) using trifluoroacetic anhydride and boron trifluoride etherate caused double cyclization to give N-formylisopavine (21). Acid catalyzed cyclization of the 1,2-dihydroisoquinoline (23) prepared from 4-phenylthio-1,2,3,4-tetrahydroisoquinoline (11) gave N-formylpavine (26). LiAlH4 reduction of the N-formates (21 and 26) gave (±)-O-methylthalisopavine (4) and (±)-argemonine (5), respectively.
- Shinohara, Tatsumi,Takeda, Akira,Toda, Jun,Sano, Takehiro
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p. 981 - 992
(2007/10/03)
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- Neuromuscular blocking agents
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1R-cis,1'R-cis isomer of a 2',2'-(3,11-dioxo-4,10-dioxatridecylene)-bis(1,2,3,4-tetrahydro-6, 7-dimethoxy-2-methyl-1-veratrylisoquinolium) said, substantially free from other geometrical and optical isomers thereof. The 1R-cis,1'R-cis isomer has been found to have an advantageous combination of pharmacological properties, notably greater neuromuscular blocking potency, weaker histamine-releasing potency, and at equivalent levels of neuromuscular blockade, fewer potential adverse effects on the autonomic nervous system (sympathetic and parasympathetic blockage), in comparison with the known mixture of geometrical and optical isomers.
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- Synthesis of Benzyltetrahydroisoquinoline Alkaloids with the Use of 1,3-Dithianes of Aromatic Aldehydes
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A practical synthesis of 1-benzyl-2-methyl-1,2,3,4-tetrahydroisoquinolines (4) is described. Condensation of 6,7-disubstituted N-methyl-3,4-dihydroisoquinolinium iodide 1 with 1,3-dithianes 2 gave addition products 3 from which alkaloids 4 were obtained by desulfuration. Key words: 1-benzyltetrahydroisoquinolines, dithianes, tetrahydroisoquinolinium alkaloids
- Brozda, D.
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p. 2665 - 2670
(2007/10/02)
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- A FACILE ROUTE TO TETRAHYDROISOQUINOLINE ALKALOIDS VIA SULFOXIDE MEDIATED CYCLIZATION
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A facile route to 1,2,3,4-tetrahydroisoquinoline framework has been developed by employing the sulfoxide mediated cyclization reaction.Utilizing the reaction developed some naturally occurring isoquinoline alkaloids have been synthesized.
- Takano, Seiichi,Iida, Hirokazu,Inomata, Kohei,Ogasawara, Kunio
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- Lewis Acid Complexed Heteroatom Carbanions; A New Concept for α-Metallation of Tertiary Amines
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BF3 complexes of typical benzylic, allylic and saturated N-methyl tertiary amines were α-lithiated, with lithium tetramethylpiperidide (LTMP) or sec-butyllithium, and were treated with electrophiles.
- Kessar, Satinder V.,Singh, Paramjit,Vohra, Rahul,Kaur, Nachhattar Pal,Singh, Kamal Nain
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p. 568 - 570
(2007/10/02)
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- ALKALOIDS FROM THE ROOTS OF Papaver pseudo-orientale (FEDDE) MEDW.
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Two new alkaloids, pseudorine (Ia) (quaternary benzyltetrahydroisoquinoline type) and pseudoronine (II) (benzil type), were isolated from the roots of Papaver pseudo-orientale (FEDDE) MEDW.This is a first occurence of this type of alkaloids in Papaveraceae.The main component of the tertiary alkaloid fraction was isothebaine accompanied by smaller amounts of orientalidine, mecambridine, bracteoline, nuciferine, protopine, and allocryptopine.The presence of salutaridine and papaverrubine D was established.Traces of coptisine and palmatine were also found in some samples.Strongly polar portion of the extract was converted to iodides.N-Methylisothebainium iodide (IIIa) (major component), pseudorine iodide (Ia), and corytuberine hydriodide (IV) (significant amounts), a minor alkaloids such as alborine iodide (alkaloid PO-5), pseudoronine (II), and magnoflorine iodide (IIIb) were isolated from this source.Structure of pseudorine was determined by UV, IR, 1H, and 13C NMR spectroscopy and using the correlation with laudanosine and codamine.Proposed structure of pseudoronine is based on the mass spectra comparison.
- Veznik, Frantisek,Taborska, Eva,Sedmera, Petr,Dolejs, Ladislav,Slavik, Jiri
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p. 1752 - 1763
(2007/10/02)
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- SODIUM HYDROGEN TELLURIDE AS A USEFUL NUCLEOPHILIC REAGENT FOR THE CLEAVAGE OF EPOXIDES AND OF QUATERNARY AMMONIUM SALTS
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Sodium hydrogen telluride opens many epoxides cleanly by an SN2 process to give telluro-alcohols, which by reduction with nickel boride afford alcohols.An intermediate telluro-alcohol was converted to olefin in high yield by treatment with p-toluene-sulphonyl chloride in pyridine.Quaternary ammonium salts are also cleaved efficiently by sodium hydrogen telluride.
- Barton, Derek H. R.,Fekih, Abdelwaheb,Lusinchi, Xavier
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p. 6197 - 6200
(2007/10/02)
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- BIOMIMETIC OXIDATIONS OF BENZYLISOQUINOLINE ALKALOUDS. II. THE BIS(SALICYLALDEHYDE)ETHYLENEDIIMINECOBALT(II)-CATALYZED OXIDATION OF BENZYLISOQUINOLINES WITH OXYGEN
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The complex bis(salicylaldehyde)ethylenediiminecobalt(II) (CoII salen) catalyzes the oxidation of benzylisoquinoline alkaloids with oxygen.Aminium radicals are formed and give rise to 1,2-dehydrobenzylisoquinoline ions.Cleavage of the C(1)-C(9) bond via C(9) oxidation is observed in some instances.
- Canonica, Luigi,Galliani, Guido,Nali, Micaela,Rindone, Bruno,Tollari, Stefano
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- Evidence for a Radical Chain Mechanism for the Knabe Reaction of 1,2-Dihydro-2-methylpapaverine
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A free radical chain mechanism is proposed for the Knabe reaction and the accompanying elimination reaction on account of their nonintegral reaction order and of successful inhibition experiments. 3,4-Dimethoxybenzyl radicals are the chain carrying species.Battersby's synthesis of N-methylpavine (19) from 1,2-dihydro-2-methylpapaverine (9) is dependent on the presence of formic acid as radical chain inhibitor.In the presence of inhibitors 1-benzyl-1,4-dihydro-2-methylisoquinolinium ions like 10 are persistent species whose chemistry can now be investigated.
- Langhals, Elke,Langhals, Heinz,Ruechardt, Christoph
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p. 1436 - 1454
(2007/10/02)
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- Novel Zinc-Promoted Alkylation of Iminium Salts. New Synthesis of Benzylisoquinoline, Phthalidylisoquinoline, and Protoberberine Alkaloids and Related Compounds
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Zinc-promoted reductive coupling reaction of iminium salts with alkyl halides was found to be a successful key reaction for synthesis of a variety of alkaloids such as benzylisoquinoline, phthalidylisoquinoline, and protoberberine alkaloids.More specifically, laudanosine, cordrastine, hydrastine, narcotine, tetrahydropalmatine, and canadine were obtained.A new route for the synthesis of the emetine and yohimbine skeletons was exploited.
- Shono, Tatsuya,Hamaguchi, Hiroshi,Sasaki, Manji,Fujita, Shumei,Nagami, Kimihiko
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p. 1621 - 1628
(2007/10/02)
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- SYTHESIS OF N-(ARYLETHYL)ARYLTHIOACETAMIDES BY THE WILLGERODT-KINDLER REACTION AND THEIR CONVERSION TO SUBSTITUTED 1-BENZYL-1,2,3,4-TETRAHYDROISOQUINOLINES
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N-(Arylethyl)arylthioacetamides were synthesized by the reaction of substituted acetophenones with 2-arylethylamines.The reaction gives good yields when compounds with substituted hydroxyl groups are used. 2,4-Diarylthiazoles were isolated as side products from the Wilgerodt-Kindler reaction.The thioamides were converted into substituted 1-benzyl-1,2,3,4-tetrahydroisoquinolines by the Bischler-Napieralski cyclization, N-methylation, and reduction of the corresponding 3,4-dihydroisoquinoline methiodide derivatives.
- Nakova, E.P.,Tolkachev, O.N.,Evstigneeva, R.P.
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p. 550 - 555
(2007/10/02)
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- The Characterization and Thermolysis of cis- and trans-(+/-)-Laudanosine N-Oxide
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The isolation and characterization of cis- and trans-(+/-)-laudanosine N-oxide is described.Thermolysis of cis-(+/-)-laudanosine N-oxide afforded the new fused and bridged heterocyclic derivatives (3RS,3aRS,8aSR)-3-(3,4-dimethoxyphenyl)-5,6-dimethyoxy-1-methyl-3,3a,8,8a-tetrahydro-1H-indeno-isoxazole (18) and (1RS,2RS,4RS)-2-(3,4-dimethoxyphenyl)-8,9-dimethoxy-5,6-dihydro-2H-1,4-methano-4H-3,4-benzoxazocine (19); other products included (+/-)-laudanosine, the Cope elimination product, (E)-N-2--4,5-dimethoxyphenyl>ethyl-N-methylhydroxyalamine (4) and 1-(3,4-dimethoxybenzyl)-7,8-dimethoxy-3-methyl -1,3,4,5-tetrahydro-2,3-benzoxazepine (17), the product of a Meisenheimer rearrangement.By contrast, trans-(+/-)-laudanosine N-oxide gave (4) in nearly quantitative yield.Some of the possible mechanistic implications of these results are discussed
- Bremner, John B.,Thuc, Le van
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p. 379 - 394
(2007/10/02)
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