- One-Pot Synthesis of Papaverine Hydrochloride and Identification of Impurities
-
Abstract: A one-pot synthesis of papaverine hydrochloride with 99.6% purity was performed using xylene as solvent for the entire process. The critical parameters of each step, as well as the impurities generated, were identified. The overall yield was improved to 63%. The proposed synthetic procedure is suitable for industrial production.
- Qiu, Zeng-Feng,Wu, Ze-Nong,Yang, Zhe-Zhou,Yu, Wen-Shuai,Zhang, Fu-Li,Zhao, Chun-Jie
-
p. 1295 - 1299
(2020/09/16)
-
- A Visible-Light Promoted Amine Oxidation Catalyzed by a Cp*Ir Complex
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Through a rapid screening of Cp*Ir complexes based on a turn-on type fluorescence readout, a [Cp*Ir(dipyrido[3,2-a : 2’,3’-c]phenazine)Cl]+ complex was found to catalyze the blue-light promoted dehydrogenation of N-heterocycles under physiological conditions. In the dehydrogenation of tetrahydroisoquinolines, the catalyst preferentially yielded the monodehydrogenated product, accompanying H2O2 generation. We surmise that this mechanism may be reminiscent of flavin-dependent oxidases.
- Davis, Holly Jane,H?ussinger, Daniel,Ward, Thomas R.,Okamoto, Yasunori
-
p. 4512 - 4516
(2020/07/27)
-
- Rh/TiO2-Photocatalyzed Acceptorless Dehydrogenation of N-Heterocycles upon Visible-Light Illumination
-
TiO2 is an effective and extensively employed photocatalyst, but its practical use in visible-light-mediated organic synthesis is mainly hindered by its wide band gap energy. Herein, we have discovered that Rh-photodeposited TiO2 nanoparticles selectively dehydrogenate N-heterocyclic amines with the concomitant generation of molecular hydrogen gas in an inert atmosphere under visible light (λmax = 453 nm) illumination at room temperature. Initially, a visible-light-sensitive surface complex is formed between the N-heterocycle and TiO2. The acceptorless dehydrogenation of N-heterocycles is initiated by direct electron transfer from the HOMO energy level of the amine via the conduction band of TiO2 to the Rh nanoparticle. The reaction condition was optimized by examining different photodeposited noble metals on the surface of TiO2 and solvents, finding that Rh0 is the most efficient cocatalyst, and 2-propanol is the optimal solvent. Structurally diverse N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, indolines, and others bearing electron-deficient as well as electron-rich substituents underwent the dehydrogenation in good to excellent yields. The amount of released hydrogen gas evinces that only the N-heterocyclic amines are oxidized rather than the dispersant. This developed method demonstrates how UV-active TiO2 can be employed in visible-light-induced synthetic dehydrogenation of amines and simultaneous hydrogen storage applications.
- Bahnemann, Detlef W.,Balayeva, Narmina O.,Dillert, Ralf,Mamiyev, Zamin,Zheng, Nan
-
p. 5542 - 5553
(2020/08/25)
-
- Reusable, homogeneous water soluble photoredox catalyzed oxidative dehydrogenation of N-heterocycles in a biphasic system: Application to the synthesis of biologically active natural products
-
Herein, a simple and efficient method for the oxidative dehydrogenation (ODH) of tetrahydro-β-carbolines, indolines and tetrahydro-(iso)quinolines is described using a reusable, homogeneous cobalt-phthalocyanine photoredox catalyst in a biphasic medium. A biphasic system offers an advantage of easy separation of the product and an efficient reusability of the homogeneous photoredox catalyst. Also, the current system significantly helps to overcome the solubility issue of the substrate and catalyst at room temperature. Its potential applications to organic transformations are demonstrated by the synthesis of various biologically active N-heterocycles such as indoles, (iso)quinolines and β-carbolines and natural products such as eudistomin U, norharmane, and harmane and precursors to perlolyrine and flazin. Without isolation and purification, the catalyst solution can be reused up to 5 times with almost comparable reactivity. Furthermore, the efficiency of the reaction was demonstrated on a gram scale. To the best of our knowledge, this is the first report on ODH reactions using a non noble, reusable and homogeneous cobalt photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Baskar, B.,Mariappan, M.,Prasanth, Arun,Sridhar, R.,Srinath, S.
-
p. 2575 - 2587
(2020/05/13)
-
- Visible-Light-Mediated Photocatalytic Aerobic Dehydrogenation of N-heterocycles by Surface-Grafted TiO2 and 4-amino-TEMPO
-
Herein, the visible-light-induced dehydrogenation of N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, and indolines in O2-containing suspensions of a commercially available titanium dioxide photocatalyst yielding the corresponding heteroarenes is presented. 4-Amino-2,2,6,6-tetramethylpipiridinyloxyl (4-amino-TEMPO) was found to exhibit a beneficial role, as it increased the yield and improved the selectivity of the dehydrogenation reaction. Both the selectivity and the yield are further enhanced by grafting 0.1 wt % of Ni(II) ions onto the TiO2 surface. It is proposed that the basic reactant adsorbs at Lewis acid sites present at the TiO2 surface. The dehydrogenation reaction is initiated by visible-light excitation of the resulting surface complex and a subsequent single-electron transfer from the excited N-heterocycle via the conduction band of TiO2 to O2. Ni(II) ions possibly serve as an electron transfer bridge between the conduction band of TiO2 and O2, while the TEMPO derivative is assumed to act as a selective redox mediator involved in reactions of the generated reactive oxygen species.
- Balayeva, Narmina O.,Zheng, Nan,Dillert, Ralf,Bahnemann, Detlef W.
-
p. 10694 - 10704
(2019/11/14)
-
- Metal-Free Dehydrogenation of N-Heterocycles by Ternary h-BCN Nanosheets with Visible Light
-
An efficient metal-free catalytic system has been developed based on hexagonal boron carbon nitride (h-BCN) nanosheets for the dehydrogenation of N-heterocycles with visible light; hydrogen gas is released in the process, and thus no proton acceptor is needed. This acceptorless dehydrogenation of hydroquinolines, hydroisoquinolines, and indolines to the corresponding aromatic N-heterocycles occurred in excellent yield under visible-light irradiation at ambient temperature. With h-BCN as the photocatalyst and water as the solvent, this environmentally benign protocol shows broad substitution tolerance and high efficiency.
- Zheng, Meifang,Shi, Jiale,Yuan, Tao,Wang, Xinchen
-
supporting information
p. 5487 - 5491
(2018/04/02)
-
- One substrate, two modes of C-H functionalization: A metal-controlled site-selectivity switch in C-H arylation reactions
-
A unique site-selectivity switch has been achieved in the ruthenium-catalyzed C-H arylation reaction of N-acetyl-1,2-dihydroisoquinolines. This metal-mediated switch is antipodal to the previous report on the palladium-mediated C-4 C-H arylation on the same substrate. Mechanistic details reveal interesting aspects of the reaction pathway, and kinetic studies bring out the difference in the modes of C-H activation adopted by the two catalytic systems.
- Tiwari, Virendra Kumar,Kamal, Neha,Kapur, Manmohan
-
supporting information
p. 262 - 265
(2017/11/27)
-
- Dehydrogenation of Nitrogen Heterocycles Using Graphene Oxide as a Versatile Metal-Free Catalyst under Air
-
Graphene oxide (GO) has been developed as an inexpensive, environmental friendly, metal-free carbocatalyst for the dehydrogenation of nitrogen heterocycles. Valuable compounds, such as quinoline, 3,4-dihydroisoquinoline, quinazoline, and indole derivatives, have been successfully used as substrates. The investigation of various oxygen-containing molecules with different conjugated systems indicated that both the oxygen-containing groups and large π-conjugated system in GO sheets are essential for this reaction. (Figure presented.).
- Zhang, Jingyu,Chen, Shiya,Chen, Fangfang,Xu, Wensheng,Deng, Guo-Jun,Gong, Hang
-
supporting information
p. 2358 - 2363
(2017/07/22)
-
- Synthesis method of quinoline compound
-
The invention discloses a synthesis method of a quinoline compound. The synthesis method of the quinoline compound comprises the following steps: taking a tetrahydroquinoline compound expressed in formula which is as shown in the description as a raw material, taking boron carbon nitrogen as a photocatalyst, adding a solvent, an oxidant and alkali, reacting under visible light radiation condition at room temperature, and purifying a reaction solution and then obtaining the quinoline compound; boron carbon nitrogen (h-BCNx) is a semiconductor polymer photocatalyst which has response to visible light and is free of metal elements; the semiconductor polymer photocatalyst has the advantages of low cost, high availability, high chemical stability, no toxicity, no harm and appropriate forbidden bandwidth and position of energy band; when the catalyst is applied to organic synthesis, the reaction process is simple to operate; the conditions are mild; the catalysis effect is excellent; the conversion rate can reach 90% or more; the yield of target products can reach 95%. The synthesis method of the quinoline compound is simple in process and low in cost, can meet the requirements of practical production, and has relatively great application potential.
- -
-
Paragraph 0021; 0022
(2017/12/04)
-
- Efficient and practical one-pot conversions of n- tosyltetrahydroisoquinolines into isoquinolines and of N-tosyltetrahydro-β- carbolines into β-carbolines through tandem β-elimination and aromatization
-
An efficient, practical, and general method for conversions of N-tosyltetrahydroisoquinolines (N-tosyl-THIQs) into isoquinolines and of N-tosyltetrahydro-β-carbolines (N-tosyl-THBCs) into β-carbolines is described. Treatment of N-tosyl-THIQs or N-tosyl-THBCs with base in dimethyl sulfoxide afforded dihydroisoquinolines or dihydro-β-carbolines as intermediates, and these were then oxidized in situ by molecular oxygen to furnish isoquinolines or β-carbolines in good to high yields. Both one-pot conversions occurred through tandem β-elimination and aromatization. An efficient method for conversions ofN-tosyltetrahydroisoquinolines (N-tosyl-THIQs) and N-tosyltetrahydro-β-carbolines (N-tosyl-THBCs) into isoquinolines and β-carbolines is described. Treatment ofN-tosyl-THIQs or N-tosyl-THBCs with base affords dihydroisoquinolines or dihydro-β- carbolines. These can be oxidized in situ by molecular oxygen to furnish isoquinolines or β-carbolines. Copyright
- Dong, Jing,Shi, Xiao-Xin,Yan, Jing-Jing,Xing, Jing,Zhang, Qiang,Xiao, Sen
-
experimental part
p. 6987 - 6992
(2011/02/24)
-
- Oxidation and deprotection of primary benzylamines by visible light flavin photocatalysis
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We report a photocatalytic oxidation procedure that can be used to convert benzylamines into their corresponding aldehydes under mild conditions without over-oxidation, using riboflavin tetraacetate as photocatalyst and blue emitting LEDs (440 nm) as light source. Oxygen is the terminal oxidant and H 2O2 and NH3 appear as the only byproducts of the oxidation of primary benzylamines. Furthermore, we have developed a photocatalytic protocol for 4-methoxybenzyl (Mob) group deprotection of primary amines and alcohols. Double bonds, benzyl-protected esters and alcohols are tolerated under the applied conditions, whereas the deprotection of protected secondary amines is not applicable. Mob-protected carboxylic acids and carboxybenzoyl (Cbz) protected amines are inert under the photodeprotection conditions. Georg Thieme Verlag Stuttgart - New York.
- Lechner, Robert,Koenig, Burkhard
-
experimental part
p. 1712 - 1718
(2010/07/05)
-
- 3,4-Dihydroisoquinolinium Salt Derivatives
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The present invention relates to 3,4-dihydroisoquinolinium salt derivatives. More specifically, the present invention relates to 3,4-dihydroisoquinolinium salt derivatives of the following chemical formula (I).
- -
-
Page/Page column 36
(2009/09/08)
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- LiCl-mediated preparation of highly functionalized benzylic zinc chlorides
-
In the presence of zinc dust (1.5-2.0 equiv) and LiCI(1.5-2.0 equiv), various benzylic chlorides bearing functional groups (iodide, cyanide, ester, ketone) are smoothly converted at 25°C to the corresponding zinc reagents without homo-coupling (≤5%). The utility of these benzylic zinc reagents is demonstrated by a short synthesis of papaverine.
- Metzger, Albrecht,Schade, Matthias A.,Knochel, Paul
-
supporting information; experimental part
p. 1107 - 1110
(2009/04/06)
-
- Diastereomeric reissert compounds of isoquinoline and 6,7-dimethoxy-3,4- dihydroisoquinoline in stereoselective synthesis
-
(Chemical Equation Presented) Chiral acid chlorides were reacted with isoquinoline and 6,7-dimethoxy-3,4-dihydroisoquinoline to form diastereomeric Reissert compounds 8-11 and 18-21, respectively. The best diastereoselectivity (80:20) was achieved in formation of the 9-phenylmenthyl derivative 20. The diastereomers of 2-l-menthoxy-carbonyl-1,2-dihydroisoquinaldonitriles (S)-8/(R)-8), formed in equal amounts, were inseparable. However, the individual diastereomers of 2-cholesteryloxycarbonyl-1,2-dihydroisoquinaldonitriles ((R)-11 and (5)-11) and the 2-l-menthoxycarbonyl-6,7-dimethoxy-1,2,3,4- tetrahydroisoquinaldonitriles ((S)-19/(R)-19)) were each readily purified. (S)-8/(R)-8 (1:1) via the corresponding anions (NaH, -40°C, DMF) with pivaldehyde yielded in 82:18 predominance the S-diastereomer of 1-isoquinolyl tert-butyl carbinyl l-menthyl carbonate ((S)-12), which was obtained in pure form by a single recrystallization; hydrolysis produced 99% pure S-(-)-1-isoquinolyl tert-butyl carbinol [(S)-16]. Reactions of the anions of diastereomeric Reissert compounds, either as mixtures or pure single species, with aromatic aldehydes and alkyl halides proceeded with at best modest selectivity (diastereomeric ratios up to 66:34 and 72:28, respectively). Therefore, it is concluded that the Reissert anions are either planar or rapidly inverting tetrahedral structures.
- Gibson, Harry W.,Berg, Michael A. G.,Dickson, Jennifer Clifton,Lecavalier, Pierre R.,Wang, Hong,Merola, Joseph S.
-
p. 5759 - 5770
(2008/02/11)
-
- Aerobic ruthenium-catalyzed oxidative transformation of secondary amines to imines
-
Aerobic, catalytic oxidation of secondary amines is performed efficiently in the presence of a diruthenium complex catalyst Ru2(OAc) 4Cl to give the corresponding imines. The catalytic system is characterized by its high selectivity, activity, and operational simplicity. Georg Thieme Verlag Stuttgart.
- Murahashi, Shun-Ichi,Okano, Yuriko,Sato, Hideomi,Nakae, Takahiro,Komiya, Naruyoshi
-
p. 1675 - 1678
(2007/12/29)
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- 3,4-DIHYDROISOQUINOLINIUM SALT DERIVATIVES
-
The present invention relates to 3,4-dihydroisoquinolinium salt derivatives. More specifically, the present invention relates to 3,4-dihydroisoquinolinium salt derivatives of the following chemical formula (I).
- -
-
Page/Page column 76
(2008/06/13)
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- FUNGAL CELL WALL SYNTHESIS GENE
-
A reporter system reflecting the transport process that transports GPI-anchored proteins to the cell wall was constructed and compounds inhibiting this process were discovered. Further, genes conferring resistance to the above compounds were identified and methods of screening for compounds that inhibit the activity of the proteins encoded by these genes were developed.Therefore, through the novel compounds, the present invention showed that antifungal agents having a novel mechanism, i.e. inhibiting the process that transports GPI-anchored proteins to the cell wall, could be achieved.
- -
-
-
- Laser versus lamp photolysis: A comparative account of the photolysis of papavarine by laser and UV lamp
-
Papavarine, when irradiated by N2 laser and UV lamp separately, gives different products. The time required is less and yields obtained are high under laser irradiation.
- Chawada, Shivraj Singh,Bokadia,Jain, Shubha
-
p. 865 - 867
(2007/10/03)
-
- Desulfonylation of N-sulfonyl tetrahydroisoquinoline derivatives by potassium fluoride on alumina under microwave irradiation: Selective synthesis of 3,4-dihydroisoquinolines and isoquinolines
-
In a solvent-free system, the microwave irradiation of mixtures of N-sulfonyl tetrahydroisoquinolines and 37% potassium fluoride supported on alumina selectively furnished 3,4-dihydroisoquinolines or isoquinolines, depending upon the reaction time.
- Silveira, Claudio C.,Bernardi, Carmem R.,Braga, Antonio L.,Kaufman, Teodoro S.
-
p. 907 - 910
(2007/10/03)
-
- Activation of iodosobenzene by catalytic tetrabutylammonium iodide and its application in the oxidation of some isoquinoline alkaloids
-
Oxidation of N-methyltetrahydroisoquinolines with iodosylbenzene in the presence of a catalytic amount of tetrabutylammonium iodide in various solvents afforded N-methyl-2H-3,4-dihydroisoquinol-1-ones in almost quantitative yields. The application of this finding to the oxidation of other isoquinolines, including tetrahydroisoquinolines, lycorine diacetate, and benzyltetrahydroisoquinolines, also afforded the corresponding lactams in good yields, however, accompanied by a few minor byproducts. Under similar conditions, tetrahydroberberine gave a rearranged compound, berberal, as the major product, accompanied by 8-oxoberberine and berberine.
- Huang, Wei-Jan,Singh, Om V.,Chen, Chung-Hsiung,Chiou, Sheng-You,Lee, Shoei-Sheng
-
p. 1069 - 1078
(2007/10/03)
-
- A novel synthesis of chiral tetrahydroisoquinolines employing silyl enol ethers in the presence of chiral acyl chlorides
-
6,7-Dimethoxyisoquinoline derivatives reacted with silyl enol ethers in a highly diastereoselective manner in the presence of an acyl chloride derived from L-alanine. (-)-Homolaudanosine was synthesized in an enantiopure form from 6,7-dimethoxyisoquinoline via six steps using this method.
- Itoh, Takashi,Nagata, Kazuhiro,Miyazaki, Michiko,Ohsawa, Akio
-
p. 1154 - 1156
(2007/10/03)
-
- Oxidation of amines with hyper valent Tert-butylperoxyiodanes: Synthesis of imines and Tert-butylperoxyamino acetalsh
-
Reaction of secondary amines with 1-tert-butylperoxy-1,2-benziodoxol-3(1H)-one (2) undergoes dehydrogenation to afford imines in the presence of K2CO3, while oxidation of tertiary amines without base produces tert-butylperoxyamino acetals.
- Ochiai, Masahito,Kajishima, Daisuke,Sueda, Takuya
-
-
- TOTAL SYNTHESIS OF PERUVIANINE, A PHENOLIC 7-OXOAPORPHINE ALKALOID OF TELITOXICUM PERUVIANUM
-
Peruvianine, a phenolic 7-oxoaporphine alkaloid from Telitoxicum peruvianum, has been sythesized via photo-Pschorr cyclization of an aminophenol precursor.
- Buck, Keith T.,Edgren, Denise L.,Blake, Geoffrey W.,Menachery, Mary D.
-
p. 2489 - 2496
(2007/10/02)
-
- Oxidation of Secondary Amines with NiSO4-K2S2O8
-
The catalytic system consisting of NiSO4 and K2S2O8 has been found to be effective for the oxidation of secondary amines to imines. 1,2,3,4-Tetrahydroisoquinoline was oxidized to 3,4-dihydroisoquinoline as the main product with a small amount of isoquinoline.N-Benzylaniline gave N-benzylideneaniline and a N-N coupling dimer.
- Yamazaki, Shigekazu
-
p. 823 - 826
(2007/10/02)
-
- Short-cut in the pomeranz-fritsch synthesis of 1-benzyl-isoquinolines; short and efficient syntheses of norrecticuline derivatives and of papaverine
-
A new methodology for the Pomeranz-Fritsch synthesis of 1-benzyl-1,2-dihydroisoquinolines avoiding pavine or isopavine troubles, has been developed. These intermediates could be reduced to their 1,2,3,4-tetrahydro congeners or aromatized to give isoquinolines, as it was demonstrated by the synthesis of some norrecticuline derivatives 4-7 and of papaverin 8.
- Hirsenkorn, Rolf
-
p. 1775 - 1778
(2007/10/02)
-
- Photoaromatization of 1,2,3,4-tetrahydroisoquinolines
-
Irradiation of 1,2,3,4-tetrahydroisoquinolines (1a-d) in the presence of phenanthraquinone or benzophenone affords the corresponding isoquinolines (3a-d) in about 50percent yield.
- Kessar, S V,Mankotia, Anil K Singh,Gujral, Gurjeet
-
p. 525 - 526
(2007/10/02)
-
- THE ALTERNATIVE SYNTHESIS OF ISOQUINOLINE NUCLEUS USING THE THERMAL ELECTROCYCLIC REACTION OF 1-AZAHEXA-1,3,5-TRIENE SYSTEM
-
The thermal electrocyclic reaction of 2-alkenylbenzaldoximes or their derivatives having conjugated 1-azahexatriene system in o-dichlorobenzene gave isoquinolines in moderate to good yields except the reaction of unsubstituted 2-alkenylbenzaldoxime and its oxime ethers.
- Hibino, Satoshi,Sugino, Eiichi,Adachi, Yukiko,Nomi, Kazuhiko,Sato, Kohichi,Fukumoto, Keiichiro
-
p. 275 - 282
(2007/10/02)
-
- Cyclopalladiated Aromatic Imines in Organic Synthesis: The Preparation of Cinnamonitriles, Cinnamates, Unsymmetrical Stilbenes, Isoquinolones, and Isoquinolines
-
The preparation and characterisation of some new ortho-palladiated benzaldimine complexes and their reaction with olefins are described.The reaction of di-μ-1-chloro-bis(2-alkyl-2,1-benzazapalladole) complexes (1) with styrene in trifluoroacetic acid-acetic acid mixtures yielded stilbene-2-carbaldehydes (10).These were converted into 2-methyl-3-phenyl-1(2H)-isoquinolones (12) via a mercury(II) mediated cyclisation of the N-methylimine derivatives of the stylbenes.Reaction of the complexes (1) with methyl acrylate produced methyl 2-(N-t-butyliminomethyl)cinnamates (7; Y=CO2Me) and with acrylonitril, the 2-(N-t-butyliminomethyl)cinnamonitriles (7; Y=CN), which upon in situ thermolysis gave the corresponding isoquinolines (8).
- Girling, Ian R.,Widdowson, David A.
-
p. 1317 - 1324
(2007/10/02)
-
- Evidence for a Radical Chain Mechanism for the Knabe Reaction of 1,2-Dihydro-2-methylpapaverine
-
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
-
p. 1436 - 1454
(2007/10/02)
-
- CYCLOPALLADATED IMINES IN SYNTHESIS 2: A NEW SYNTHESIS OF ISOQUINOLINES
-
Reaction of cyclopalladated arylimines with acrylonitrile, followed by thermolysis gives isoquinolines by an electrocyclic ring forming process and a subsequent eliminative aromatisation step.
- Girling, I. R.,Widdowson, D. A.
-
p. 4281 - 4284
(2007/10/02)
-
- NICKEL-PHOSPHINE COMPLEX-CATALYZED GRIGNARD COUPLING-II; GRIGNARD COUPLING OF HETEROCYCLIC COMPOUNDS
-
A general, versatile method for alkylation and arylation of haloheterocyclic compounds is reported.In the presence of a catalytic quantity of , where dppp stands for Ph2P(CH2)3PPh2, bromothiophenes, halopyridines, haloquinoline, and haloisoquinolines reacted with alkyl and aryl Grignard reagents at room temperature or at ether refluxing temperature to give the cross-coupling products.The coupling reactions has been applied to the synthesis of isoquinoline alkaloids.Reactivities of 2-thienyl and 2-pyridyl Grignard reagents have also been examined.
- Tamao, K.,Kodama, S.,Nakajima, I.,Kumada, M.,Minato, A.,Suzuki, K.
-
p. 3347 - 3354
(2007/10/02)
-
- A SIMPLIFIED ISOQUINOLINE SYNTHESIS
-
A simple variation of the Pomeranz-Fritsch cyclization provides a short, efficient route to isoquinolines.Treatment of benzylic halides or mesylates 1 with the sodium anion of N-tosyl aminoacetaldehyde dimethyl acetal (2) followed by acid-catalyzed cyclization provides an effective, two-step preparation of isoquinolines 4.
- Boger, Dale L.,Brotherton, Christine E.,Kelley, Marshall D.
-
p. 3977 - 3980
(2007/10/02)
-
- Synthesis of Isoquinolines from Indenes
-
A general procedure for the synthesis of isoquinolines from appropriately substituted indenes is described.Ozonolysis of the indenes followed by reductive workup gives intermediate homophthalaldehydes which are treated with ammonium hydroxide to give the isoquinolines.This "one-pot", three-step reaction sequence was applied to the formation of all of the mono-C-methyl-substituted isoquinolines in a regiospecific manner.The procedure is applicable to both electron-withdrawing and electron-donating substituents on the indene system.In this manner the 6- and 7-nitro-,-bromo-, and -iodoisoquinolines were prepared.
- Miller, R. Bryan,Frincke, James M.
-
p. 5312 - 5315
(2007/10/02)
-
- A ONE-POT ISOQUINOLINE SYNTHESIS BY CYCLODEHYDROGENATION OF BENZYLAMINOACETALS WITH CHLOROSULFONIC ACID
-
A direct preparation of the fully aromatized isoquinolines (3a-l) by the cyclodehydrogenation of benzylamnoacetals (2a-l) with chlorosulfonic acid is described.Comparing the behavior of chlorosulfonic acid with that of sulfuric acid toward 1,2-dihydroisoquinoline, it is able to be suggested that benzylaminoacetals were cyclized first to 1,2-dihydroisoquinolines, subsequently, dehydrogenated to the fully aromatized isoquinolines by the hydride abstraction with ClSO3H.Subtitution by a larger R3 group than isopropyl in the acetal ArCH(R3)NHCH2CH(OEt)2, interfered this second step, so the corresponding isoquinolines could not be obtained.
- Kido, Kazuko,Watanabe, Yasuo
-
p. 1151 - 1154
(2007/10/02)
-
