Synthesis of 5-amino-2,3-dihydro-1H-1,4-benzodiazepines

A number of 5-amino-2,3-dihydro-lH-1,4-benzodiazepines (II) have been prepared from the reaction of 5-methylmercapto-2,3-dihydro-1H-1,4-benzodiazepine (I) with amines. Another alternate approach based on the cyclodehydration of the ureic compounds (IV) was unsuccessful. The synthesis of I was accomplished by methylation of the 1,2,3,4-tetrahydro-5H-5-thioxo-1,4-benzodiazepine (VI) with dimethyl sulfate in methanol-dioxane. Another attempted method for the synthesis of I is also presented. J. Heterocyclic Chem., 14, 985 (1977)     

Ein neuer zugang zu indeno[1,2-b]pyridinen

A new synthesis of 5H-indeno[1,2-6]pyridines [IV] starting from 4-cyanobutyrophenones [I] or their cyclization products, the 6-phenyl-3,4-dihydropyridin-2-ones [II], is reported. The condensation of I or II in polyphosphoric acid with aromatic or heteroaromatic aldehydes [III] yields 1,2,3,4-tetrahydro-5H-indeno[1,2-b]pyridin-2-ones [IV]. 2,3,4,4a,5,9b-Hexahydro-1H-indeno[1,2-b]pyridines [X, XI] which were previously difficult to obtain can now be easily synthesized from compounds IV.     

New tetracyclic compounds containing the β-carboline moiety

Oxidation of 1-methyl-3-methoxycarbonyl-β-carboline with selenium dioxide gave 1-formyl-3-methoxycarbonyl-β-carboline II . Compound II reacted with acetic or propionic anhydride to give easily the 2-methoxycarbonyl-6H-indolo[3,2,1-d,e][1,5]naphthyridin-6-ones III ; reaction of II with some primary amines led to the formation of the Schiff bases IV , which were reduced to the 1-aminomethyl-3-methoxycarbonyl-β-carbolines V with sodium borohydride. Cyclization of V with aqueous formaldehyde led to the pyrimido[3,4,5-lm]pyrido[3,4-b]indoles VI . Analogously, cyclization with formaldehyde, acetone or 1,1′-carbonyldiimidazole of the 3-aminomethyl- 1,2,3,4-tetrahydro-β-carbolines VIII , obtained by reaction of 3-methoxycarbonyl-1,2,3,4-tetrahydro-β-carboline VII with amines followed by lithium aluminium hydride reduction of the resulting amides, gave the imidazo[1′,5′-1,6]pyrido[3,4-b]indoles IX and X . Dieckmann cyclization of 3-methoxycarbonyl-2-[(3-ethoxycarbonyl)-1-propyl]-1,2,3,4-tetrahydro-β-carboline XI led to a 1:1 mixture of the β-ketoesters XII and XIII , which underwent deethoxycarbonylation to 5,6,8,9,10,11,11a,12-octahydroindolo[3,2-b]quinolizin-11-one XIV . Finally, the polyphosphoric acid (or esters) catalyzed cyclization of the N-acyl derivatives XVI of 3-hydrazinocarbonyl-β-carboline XV led smoothly to the 3-(1,3,4-oxadiazol-2-yl)-β-carbolines XVII .     

Copper and palladium complexes with substituted pyrimidine-2-thiones and 2-thiouracils: syntheses,spectral characterization,and X-ray crystallographic study

Copper(I) and palladium(II) complexes containing 5-acetyl-6-methyl-1,2,3,4-tetrahydropyrimidine-2-thione (L¹), ethyl 4,6-dimethyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (L²), cis-5-acetyl-6-ethyl-5,6-dihydro-2-thiouracil (L³), and 5,6-dihydro-2-thiouracil (L⁴) have been synthesized. All complexes were characterized by elemental analysis, IR, ¹H, and ¹³C NMR spectroscopy. To assign bands in the IR spectra of L¹ and L² and complexes with Cu(I) and Pd(II), deuterium substitution of movable protons at N-atoms was used. The crystal structures of two compounds, [Cu(L²)₂Cl] and [Pd(L⁴)₂Cl₂], were determined by X-ray single-crystal and powder diffraction, respectively. In [Cu(L²)₂Cl], copper has a rare coordination number of three and triangular surrounding of two neutral L² molecules, coordinated through sulfurs, and chloride. In [Pd(L⁴)₂Cl₂], palladium has a standard square-planar geometry, formed by two uracil molecules and two chlorides. A new method for the synthesis of 5,6-dihydro-2-thiouracil, starting from β-aminopropionic acid, was suggested.     

Optically active diaryl tetrahydroisoquinoline derivatives

In (1R,3S)‐6,7‐dimethoxy‐3‐(methoxydiphenylmethyl)‐1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline, C₃₁H₃₁NO₃, (I), and (1R,3S)‐2‐benzyl‐3‐[diphenyl(trimethylsiloxy)methyl]‐6,7‐dimethoxy‐1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline, C₄₀H₄₃NO₃Si, (II), the absolute configurations have been confirmed to be R and S at the isoquinoline 1‐ and 3‐positions, respectively, by NMR spectroscopy experiments. Both structures have monoclinic (P2₁) symmetry and the N‐containing six‐membered ring assumes a half‐chair conformation. The asymmetric unit of (I) contains one molecule, while (II) has two molecules within the asymmetric unit. These structures are of interest with respect to the conformation around the exocyclic C—C bond: (I) displays an ap (antiperiplanar) conformation, while (II) displays an sc‐exo (synclinal) conformation around this bond. These conformations are significant for stereocontrol when these compounds are used as catalysts. Various C—H...π and C—H...O bonds link the molecules together in the crystal structure of (I). In the crystal structure of (II), three intermolecular C—H...π hydrogen bonds help to establish the packing.     

Synthesen in der Isochinolinreihe: Zur Ätherspaltung 6,7,8-trimethoxy-substituierter Isochinolinverbindungen mit wässeriger Salzsäure

Zusammenfassung Die Behandlung des 6,7,8-trimethoxy-substituierten 1,2,3,4-Tetrahydroisochinolins (I) mit 20proz. wäßr. HCl ergibt zur Hauptsache das entsprechende 6,7,8-Trihydroxyderivat II. Die Behandlung des analog substituierten 3,4-Dihydroisochinolins IV und Isochinolins XXI führt hauptsächlich zu den 6,8-dimethoxy-7-hydroxy-substituierten Isochinolinverbindungen V und XXII, unter selektiver Spaltung der in 7-Stellung befindlichen Methoxyl-gruppe. Die Konstitution von V und XXII konnte durch Synthese und Abbau bewiesen werden.

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Treatment of the 6,7,8-trimethoxy-substituted 1,2,3,4-tetrahydroisoquinoline I with 20% aqueous HCl yields predominantly the corresponding 6,7,8-trihydroxy derivative II. The analogously substituted 3,4-dihydroisoquinoline IV and isoquinoline XXI are converted into their 6,8-dimethoxy-7-hydroxy derivatives V and XXII under these conditions. The constitution of these phenols was established by synthesis and degradation.

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Herrn Prof. Dr.H. Bretschneider zum 60. Geburtstag gewidmet.     

R 和 s-1-(3'-溴-4'-甲氧基)苄基-2-甲基-6-甲氧基-7-羟基-1, 2,3,4-四氢异喹啉的合成

本文报道了R和S-1-(3'-溴-4'-甲氧基)苄基-2-甲基-6-甲氧基-7-羟基-1,2,3,4-四氢异喹啉的合成。     

Borane-Catalyzed Tandem Cyclization/Hydrosilylation Towards Enantio- and Diastereoselective Construction of trans-2,3-Disubstituted-1,2,3,4-Tetrahydroquinoxalines

Recent years have witnessed marked progress in the efficient synthesis of various enantioenriched 1,2,3,4-tetrahydroquinoxalines. However, enantio- and diastereoselective access to trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines remains much less explored. Herein we report that a frustrated Lewis pair-based catalyst generated via in situ hydroboration of 2-vinylnaphthalene with HB(C₆F₅)₂ allows for the one-pot tandem cyclization/hydrosilylation of 1,2-diaminobenzenes and 1,2-diketones with commercially available PhSiH₃ to exclusively afford trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines in high yields with excellent diastereoselectivities (>20 : 1 dr). Furthermore, this reaction can be rendered asymmetric by using an enantioenriched borane-based catalyst derived from HB(C₆F₅)₂ and a binaphthyl-based chiral diene to give rise to enantioenriched trans-2,3-disubstituted 1,2,3,4-tetrahydroquinoxalines in high yields with almost complete diastereo- and enantiocontrol (>20 : 1 dr, up to >99 % ee). A wide substrate scope, good tolerance of diverse functionality and up to 20-gram scale production are demonstrated. The enantio- and diastereocontrol are achieved by the judicious choice of borane catalyst and hydrosilane. The catalytic pathway and the origin of the excellent stereoselectivity are elucidated by mechanistic experiments and DFT calculations.     

Synthesis and alkylation ofN-methylmorpholinium 5-cyano-4-(3- and 4-hydroxyphenyl)-2-oxo-1,2,3,4-tetrahydropyridine-6-thiolates

The reactions of 3- or 4-hydroxybenzaldehydes with cyanothioacetamide and Meldrum's acid in the presence ofN-methylmorpholine affordedN-methylmorpholinium 5-cyano-4-(3-or 4-hydroxyphenyl)-2-oxo-1,2,3,4-tetrahydropyridine-6-thiolates, respectively. The resulting compounds were used in the synthesis of substituted 6-alkylthio-1,2,3,4-tetrahydropyridin-2-ones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2333–2336. December, 1999.     

Synthesis and structures of 3-hydroxy-6-(R-phenylazo)-7,8-benzo-1,2,3,4-tetrahydroquinolines as products of analytical test reactions for nitrite and nitrate anions

An improved procedure was proposed for the synthesis of 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline, which is used as a reagent for the analytical test reaction for nitrate and nitrite anions based on azo coupling with diazo compounds. 3-Hydroxy-6-(R-phenylazo)-7,8-benzo-1,2,3,4-tetrahydroquinolines (R = 2-COOH, 4-COOH, or 4-SO₃H) were synthesized by azo coupling reactions in 65–70% yields. The structures of these compounds were confirmed by elemental analysis, ¹H NMR and IR spectroscopy, and X-ray diffraction. Based on the X-ray data, the bathochromic shift in the UV spectrum of the o-carboxy isomer compared to the p-carboxy isomer (Δλ_max = 50 nm) is attributed to a strong intramolecular hydrogen bond. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1027–1031, June, 2006     

A convenient synthesis and antifungal activity of 1-aryl-1H- and 1-aryl-3-heteroaryl-1H-pyrazolo[3,4-b]quinoxalinesA Convenient Synthesis and Antifungal Activity

Novel 1-aryl-1H- and 1-aryl-3-heteroaryl-1H-pyrazolo[3,4-b]quinoxalines (flavazoles) 9a-c, 12, 13 were synthesized from 3-methyl-2-oxo-1,2-dihydroquinoxaline 5 and the 3-triazolylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline 6, respectively, via a facile hydrazone synthesis using aryl diazonium salts. Some of the above flavazoles and their related compounds exhibited the antifungal activity in some extent. The above results are described.     

1-Phenyl-6,7-disubstituted-aminopropyl)-1,2,3,4-tetrahydroisoquinolines as possible antituberculer agents

The Condensation of 3,4-disubstituted phenylethylamine and benzaldehyde furnished l-phenyl-6,7-disubstituted-1,2,3,4-tetrahydroisoquinolines l. which on reaction with 1,3-dibromopropane gave l-phenyl-6,7-disubstituted-2-(3-bromoprophyl)-1,2,3,4-tetrahydroisoquinolines 2. The reaction of 2 with different secondary amines resulted in the synthesis of 3. The compounds 3 were screened for their in vitro antituberculer activity against Mycobacterium smegmatis, and some of them have been found to be total inhibitors of M. Smegmatis     

Synthesis and dehydration reaction of 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,2,3,4-tetrahydronaphth-2-ol: possible intermediate of Lasofoxifene

The paper deals with a simple and sufficient synthesis of key precursor of Lasofoxifene. The 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-3,4-dihydronaphthalene was prepared by a sequence of five reactions steps: first 1-(4-benzyloxyphenyl)-6-methoxy-3,4-dihydronaphthalene was prepared (70%), and this was quantitatively epoxidized to 7b-[4-(benzyloxy)phenyl]-5-methoxy-1a,2,3,7b-tetrahydronaphtho[1,2-b]oxirene. Catalytic (ZnI₂) isomerization of the epoxide gave 1-(4-benzyloxyphenyl)-6-methoxy-1,2,3,4-tetrahydronaphthalen-2-one (75%). Its subsequent reaction with phenylmagnesium bromide gave 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,2,3,4-tetrahydro-2-naphthol (87%). Acid-catalysed dehydration of this alcohol by polyphosphoric acid (25°C) provides 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-1,4-dihydronaphthalene (80%). Dehydration in the system of acetic anhydride/polyphosphoric acid gives 1-(4-benzyloxyphenyl)-6-methoxy-2-phenyl-3,4-dihydronaphthalene (66%).     

Imino Diels-Alder Reactions: Efficient Synthesis of 2-Aryl-4-(2′-oxopyrrolidinyl-1′)-1,2,3,4-tetrahydroquinolines catalyzed by Antimony(III) Sulfate

Antimony(III) sulfate is found to catalyze the imino Diels-Alder reaction of Schiff’s bases with N-vinylpyrrolidin-2-one to afford 2-aryl-4-(2′-oxopyrrolidinyl-1′)-1,2,3,4-tetrahydroquinolines. One-pot synthesis of 1,2,3,4-tetrahydroquinolines from 3-nitro benzaldehyde and aromatic amines with N-vinylpyrrolidin-2-one catalyzed by antimony(III) sulfate is also reported. This catalyst is inexpensive, easily available, and it was also found that catalyst could be recovered quantitatively and reused without much loss of catalytic activity.     

Optical characterisation of organosilane-modified nanocrystalline diamond films

We report on an optical characterisation of nanocrystalline diamond films photochemically functionalised with the organosilane-coupling agent, N ¹-(3-(trimethoxysilyl)propyl)hexane-1,6-diamine (alternative names: N-(6-aminohexyl)aminopropyl-trimethoxysilane, (3-(6-aminohexylamino)propyl) trimetoxysilane, AHAPS). The presence and homogeneity of the organosilane layers were detected by fluorescence microscopy and infrared reflectance-absorbance spectroscopy. The results indicated that a homogeneous surface coverage with organosilane layers was achieved on diamond surfaces which were modified either by hydrogen or by oxygen plasma treatment. The functionalised nanocrystalline diamonds present a promising solution in future biosensor applications.     

Studies on Debenzylation and Photolysis of 1-Benzyl- and 1-(β-Phenethyl)-1,2,3,4-tetrahydroisoquinolines

Debenzylation of 1-(3-benzyloxybenzyl)-1,2,3,4-tetrahydroisoquinolines 1 , 6 , 7 with hydrochloric acid and ethanol gave the corresponding phenolic isoquinolines 2 , 8 , 9 and tetrahydroprotoberberines 4 , 12 , 13 . Compounds 2 , 8 , 9 on photolysis also gave, besides the expected noraporphines 3 , 10 , 11 , the tetrahydroprotoberberines 4 , 12 , 13 [1–4] (Schemes 1 and 2). 6-Benzyloxy-1-(5-benzyloxy-2-bromo-benzyl)-1,2,3,4-tetrahydroisoquinoline (27a) containing no methoxy or methylenedioxy groups either in ring A or C does not give protoberberine during debenzylation; but 28 , the debenzylation product of 27a , on photolysis gives both the noraporphine 29 and the tetrahydroprotoberberine 30 (Scheme 6), proving that during debenzylation of 1-(3-benzyloxybenzyl)-1,2,3,4-tetrahydroisoquinolines containing additional methoxy or methylenedioxy groups, the necessary formaldehyde comes from the latter groups. During photolysis both the methoxy groups (methylenedioxy groups) and the C(3) atom of the tetrahydroisoquinoline moiety provide the formaldehyde. Veratrole under debenzylation and photolytic conditions and tetrahydroisoquinoline under the latter condition also give rise to formaldehyde (Schemes 8 and 10). The novel bromohomoprotoberberine 43 along with 42 was formed during debenzylation of the 1-phenethyl-1,2,3,4-tetrahydroisoquinoline 41 . Photolysis of 42 yielded the novel nor-homoaporphine 44 , in addition to 43 ; the latter was debrominated to give the homoberbine 45 .     

Investigation of the products of the reaction of epichlorohydrin with aromatic amines

N-(-Chloro--hydroxy)propyl derivatives of 5-chloro-1-naphthylamine, 8-chloro-1-naphthylamine, and 5-cyano-1-naphthylamine were obtained. They were cyclized to 1,2,3,4-tetrahydro-3-hydroxy-7-chlorobenzo[f]quinoline (II), 1,2,3,4-tetrahydro-3-hydroxy-10-chlorobenzo-[fJquinoline (VII), and 1,2,3,4-tetrahydro-3-hydroxy-7-cyanobenzo[f]quinoline (X). Chlorination at the 6 position to form 1,2,3,4-tetrahydro-3-hydroxy-6,7-dichlorobenzo[f]quinoline occurs under the action of thionyl chloride on II at room temperature. The action of thionyl chloride on II, VII, and X at elevated temperatures leads not only to chlorination at the 6 position but also to aromatization of the tetrahydropyridine ring to form, respectively, 6,7-dichlorobenzo[f]quinoline (V), 6,10-dichlorobenzo[f]quinoline (VIII), and 6-chloro-7-cyanobenzo[f]quinoline (XIII).See [5] for Communication V.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1522–1525, November, 1970.     

A study of the Claisen—Eschenmoser reaction for hydroxymethylbenzofurans and-indoles

N,N-Dimethylacetamide dimethyl acetal reacted with 5(7)-substituted 2-(hydroxy-methyl)benzofurans to give N,N-dimethyl-2-(2-methylbenzofuran-3-yl)acetamides. Analogous reactions with 3-(hydroxymethyl)indole and 1-hydroxy-6-methyl-1,2,3,4-tetrahydro-carbazole afforded N,N-dimethyl-3-(3-indolyl)propionamide and N, N-dimethyl-2-(6-methyl-1,2,3,4-tetrahydrocarbazol-1-yl)acetamide, respectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 314–318, February, 2007.     

Imino <Emphasis Type="Italic">Diels-Alder</Emphasis> Reactions: Efficient Synthesis of 2-Aryl-4-(2′-oxopyrrolidinyl-1′)-1,2,3,4-tetrahydroquinolines catalyzed by Antimony(III) Sulfate

Summary. Antimony(III) sulfate is found to catalyze the imino Diels-Alder reaction of Schiff’s bases with N-vinylpyrrolidin-2-one to afford 2-aryl-4-(2′-oxopyrrolidinyl-1′)-1,2,3,4-tetrahydroquinolines. One-pot synthesis of 1,2,3,4-tetrahydroquinolines from 3-nitro benzaldehyde and aromatic amines with N-vinylpyrrolidin-2-one catalyzed by antimony(III) sulfate is also reported. This catalyst is inexpensive, easily available, and it was also found that catalyst could be recovered quantitatively and reused without much loss of catalytic activity.     

Synthesis of 2′,3′-dihydrospiro[benzofuran-2(3H),4′(1′-H)isoquinoline]s. A novel heterocyclic ring system

The synthesis of a novel 2′,3′-dihydrospiro(benzofuran-2(3H),4′(1′H)isoquinoline] ring system ( IV ) by a nucleophilic aromatic fluoride displacement-cyclization is described. Preparation of various derivatives of IV as well as the precursor 4-(2-fluorobenzyl)-1,2,3,4-tetrahydro-4-isoquinolinols is also described.