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Yves Troin

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Aimé Ainin SOMBORO

Ndale N G I D A Zakawa

Adamawa State University,Mubi,Nigeria.

Dr. M. I. Alkali

Imoh Imeh Johnny

University of uyo, Nigeria

Martin KIENDREBEOGO

Souleymane SANON

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Papers by Yves Troin

An ethnobotanical and phytochemical study of the African medicinal plant Guiera senegalensis J. F. Gmel

Journal of Medicinal Plants Research, 2011

The Sudano-Sahelian species Guiera senegalensis J. F. Gmel. is a small shrub found mainly in West... more The Sudano-Sahelian species Guiera senegalensis J. F. Gmel. is a small shrub found mainly in West Africa. It is well known in the Sahel, where it grows gregariously, forming abundant single-species colonies on fallow clay or sandy soils. Its widespread use in traditional medicine prompted us to conduct an ethnobotanical survey and phytochemical screening of this plant. The chemical analysis tests we carried out confirmed the results of earlier work. The main classes of secondary metabolites, namely anthraquinones, terpenoids, saponins, alkaloids, coumarins, mucilages, flavonoids, tannins, and cardiotonic and cyanogenic heterosides were assayed in different organs of the plant: leaves, fruits, and root and stem bark. New uses of different parts of G. senegalensis by the traditional medical practitioners were recorded especially the use of decoctions of leaves to relieve abdominal pain and migraines. The further investigation of the potentially active constituents of G. senegalensis s...

Anti-Inflammatory and Cytotoxic Potential of New Phenanthrenoids from Luzula sylvatica

Molecules, 2020

Phenanthrenoids have been widely described, in the Juncaceae family, for their biological propert... more Phenanthrenoids have been widely described, in the Juncaceae family, for their biological properties such as antitumor, anxiolytic, anti-microbial, spasmolytic, and anti-inflammatory activities. The Juncaceae family is known to contain a large variety of phenanthrenoids possessing especially anti-inflammatory and cytotoxic properties. Luzula sylvatica, a Juncaceae species, is widely present in the Auvergne region of France, but has never been studied neither for its phytochemical profile nor for its biological properties. We investigated the phytochemical profile and evaluated the potential anti-inflammatory activities of L. sylvatica aerial parts extracts. A bioassay-guided fractionation was carried out to identify the most active fractions. Nine compounds were isolated, one coumarin 1 and eight phenanthrene derivatives (2–9), including four new compounds (4, 5, 8 and 9), from n-hexane and CH2Cl2, fractions. Their structures were established by HRESIMS, 1D and 2D NMR experiments. T...

$Figure 1. ROS production of blood leucocytes, incubated with the methanolic extract or fractions (10, 25 and 50 ug/mL) and stimulated with PMA (1 uM) for 1h. Values are expressed as percentage of the control (cells incubated with PMA and without extract). Data are shown as means + SEM (n = 3-6); * p < 0.05 compared with Control. All results are expressed as a percentage, with control (i.e., cells with PMA but without extract) normalized as 100%.$

$Figure 2. Isolated compounds from CH2Cly and n-hexane fractions. n-hexane fraction was first purified by steric exclusion method using biobeads, then by column chromatography. Six major compounds were isolated, juncunol (3) [23], juncuenin A (6), dehydrojuncuenin A (7) [26] and three new compounds (5, 8, and 9), with original phenanthrene structures, were identified.$

$Figure 3. Key COSY, HMBC and NOESY correlations for compounds 4, 5, 8 and 9. -2. The 'H and °C NMR data showed the presence an aldehyde function with the corresponding arbon at dc 193.5 ppm (CH) and a singlet proton at 64 10.07 ppm. As previously reported in terature [28-30], the aldehyde function was located on C-5. This was confirmed by the HMBC orrelations from H-12 (64 10.07) to C-6 (6¢ 127.2). The position of all the substituents and 1e chemical shifts of all the protons and the carbons were attributed using HMBC and COSY orrelations as described on Figure 3. The structure of the new compound 9 was determined as -hydroxy-1,7-dimethyl-9,10-dihydrophenanthrene-5-carbaldehyde, named sylvaticin C. The nine isolated compounds were tested on leucocytes ROS production as described above for the five fractions. Four of them inhibited ROS production significantly in a dose-dependent manner: compounds 2, 4, 8, and 1 (Figure 4), although the last one had to be tested at higher concentration to be effective.$

Stereoselective strategies for the construction of polysubstituted piperidinic compounds and their applications in natural products’ synthesis

Organic Chemistry Frontiers, 2017

An abridged and far-reaching review communication on the construction of the polysubstituted pipe... more

Advances in tetrahydropyrido[1,2-a]isoindolone (valmerins) series: Potent glycogen synthase kinase 3 and cyclin dependent kinase 5 inhibitors

European journal of medicinal chemistry, Jan 27, 2015

An efficient synthetic strategy was developed to modulate the structure of the tetrahydropyridine... more An efficient synthetic strategy was developed to modulate the structure of the tetrahydropyridine isoindolone (Valmerin) skeleton. A library of more than 30 novel final structures was generated. Biological activities on CDK5 and GSK3 as well as cellular effects on cancer cell lines were measured for each novel compound. Additionally docking studies were performed to support medicinal chemistry efforts. A strong GSK3/CDK5 dual inhibitor (38, IC50 GSK3/CDK5 32/84 nM) was obtained. A set of highly selective GSK3 inhibitors was synthesized by fine-tuning structural modifications (29 IC50 GSK3/CDK5 32/320 nM). Antiproliferative effects on cells were correlated with the in vitro kinase activities and the best effects were obtained with lung and colon cell lines.

A β,β′-ketoaminoester as a valuable tool for the asymmetric construction of substituted homopipecolic esters: application to a formal synthesis of (+)-Calvine

Tetrahedron: Asymmetry, 2004

A highly diastereoselective 1,4-addition involving Davies' lithium amide is employed as the key r... more A highly diastereoselective 1,4-addition involving Davies' lithium amide is employed as the key reaction to prepare, in five steps from ethyl acetoacetate, an enantiomerically pure keto protected b,b 0-ketoaminoester. This latter was reacted with aldehydes in an intramolecular Mannich process and furnished a direct and stereoselective access to substituted homopipecolates. The validity of this approach was achieved through a new formal asymmetric synthesis of alkaloid (þ)-Calvine.

Diastereoselective elaboration of 2,3,4-substituted piperidines using diene iron tricarbonyl complexes. Total synthesis of (±)-dienomycin C and (±)-4-epi-dienomycin C

Tetrahedron Letters, 1996

The diastereoselective formation of 2,3,4-substituted piperidines is achieved by condensation of ... more

Simple pyridylmethylamines: efficient and robust N,N-ligands for Suzuki–Miyaura coupling reactions

Tetrahedron Letters, 2010

... 27 July 2010 Accepted Date: 28 July 2010 Please cite this article as: Gunawan, MA., Qiao, C.,... more

N-Heterocyclic Pyridylmethylamines: Synthesis, Complexation, Molecular Structure, and Application to Asymmetric Suzuki–Miyaura and Oxidative Coupling Reactions

Organometallics, 2011

Acetyl-d3 Chloride: A Convenient Nonchiral Derivatizing Agent (NCDA) for a Facile Enantiomeric Excess Determination of Amines through Deuterium NMR

The Journal of Organic Chemistry, 1996

Chiral resolution of functionalized piperidine enantiomers by capillary electrophoresis with native, alkylated and anionic β-cyclodextrins

Journal of Chromatography A, 1998

Anionic sulfobutylether-b-CD (SBE-b-CD) has been found to be more suitable and convenient than na... more Anionic sulfobutylether-b-CD (SBE-b-CD) has been found to be more suitable and convenient than native or alkylated b-CDs for the enantiomeric separation of functionalized piperidines. This anionic cyclodextrin derivative facilitates the separation of cationic enantiomers since the mobility of the complexed form is opposed to that of the free cation. The addition of low concentrations of SBE-b-CD (5-20 mg / ml) to the phosphate buffer, pH 2.6, allows a fast and baseline separation of dienomycine C (R 51.70) and also of 4-protected 2-alkylated piperidine (R 51.26) into their enantiomers. s s Compared to neutral CDs, this chiral selector offers the benefits of an increased aqueous solubility and a better resolution because this anionic CD acts as a countermigrating complexing agent versus cationic drugs.

A Simple Stereoselective Route to α-Trifluoromethyl Analogues of Piperidine Alkaloids

European Journal of Organic Chemistry, 2006

ABSTRACT The highly diastereoselective synthesis of five trifluoro-substituted analogues of mono-... more ABSTRACT The highly diastereoselective synthesis of five trifluoro-substituted analogues of mono-, di-, and trisubstituted piperidine alkaloids was accomplished in two to four steps from 2-trifluoromethyl keto-protected 4-piperidones, prepared by an intramolecular Mannich-type reaction methodology. A simple stereoselective elaboration of new 2-(trifluoromethyl)-4-piperidinols and 4-amino-2-(trifluoromethyl) piperidines is also described. ((c) Wiley-VCH Verlag GmbH &amp; Co. XGaA, 69451 Weinheim, Germany, 2006)

Efficient synthesis of β’-amino-α,β-unsaturated ketones

Beilstein Journal of Organic Chemistry, 2013

A general and simple procedure to access chiral β'-amino-α,β-enones, in seven steps, from an ... more A general and simple procedure to access chiral β'-amino-α,β-enones, in seven steps, from an α,β unsaturated ester has been described. The use of a Horner–Wadsworth–Emmons reaction as a key step for generating the β'-amino-α,β-enones, permits access to a range of substrates under mild conditions and in moderate to high yield.

Synthesis of 2-thioxoimidazolin-4-one and thiazolo[3,2-a]-benzimidazole derivatives from substituted maleimides

Arkivoc, 2010

We describe here a hetero Michael-type reaction, involving maleimides and 2cyanoacetichydrazide o... more We describe here a hetero Michael-type reaction, involving maleimides and 2cyanoacetichydrazide or 2-mercaptobenzimidazole, followed by an opening cyclization reaction with isothiocyanates. This reaction allows the preparation of new 2-thioxoimidazolidin-4-one and thiazolo[3,2-a]benzimidazole derivatives depending on the nucleophile used.

Diastereoselective preparation of cyclic β-aminoketals. Application to the total synthesis of piperidine alkaloids

Arkivoc, 2007

We describe here the diastereoselective synthesis of cyclic β-aminoketone derivatives which are v... more We describe here the diastereoselective synthesis of cyclic β-aminoketone derivatives which are very powerful synthons for alkaloid synthesis. They were stereoselectively prepared by condensation of a chiral lithium amide on an α,β-unsaturated ester which possesses a leaving group in ω−position. The usefulness of these compounds was demonstrated through the synthesis of indolizidine 209D, an alkaloid isolated from skin extracts of South American frogs and also in the preparation of allosedridine which has been isolated from Sedum acre.

Photocyclization of ketolactams: a new synthesis of functionalized aza-1-bicyclo[x.y.0] alkanes

Journal of Photochemistry, 1981

Photoreduction d'arylcetones par les amides et les lactames: applications synthetiques

Tetrahedron, 1979

ABSTRACT Benzophenone is photoreduced by lactams and amides. In this reaction the hydrogen atom α... more ABSTRACT Benzophenone is photoreduced by lactams and amides. In this reaction the hydrogen atom α to the lactam nitrogen is abstracted regioselectively, and radical coupling leads to adducts. The reaction is general and comparable to an hydroxyalkylation α to the nitrogen atom. Its quantum yield is 0.13 in the case of N-methyl 2-pyrrolidone in CH3CN or in C6H6. Adducts obtained with acetophenone and p,p&#39;-dimethoxy benzophenone are described. The reduction of adduct 12yields the diphenylethanolamine 22 and 12 is dehydrated to give the enamide 21.

Photocyclisation de N-benzoylenamines. Syntheses de spirocyclohexanes en serie isoquinoleine

Tetrahedron, 1991

Substituted N-benzoylenammes are easily prepared from benzoyl chlorides and cycloalkane carboxald... more

Photocyclization of enaminoesters: Access to 2,3 -dihydroindoles spiroimides

Tetrahedron Letters, 1996

The synthesis of spiroindolines imides 15a,b using a photochemical reaction and their transformat... more

Photocyclization of aryl enaminones. An efficient route to indole alkaloid synthons

Canadian Journal of Chemistry, 1989

The photocyclization of enaminones was extended to aryl enaminones bearing a substituent on the a... more The photocyclization of enaminones was extended to aryl enaminones bearing a substituent on the aromatic moiety. This reaction was studied in order to achieve the synthesis of indole alkaloid synthons. Trials of regioselectivity control were made by using groups with enhanced steric hindrance. The reactivity of secondary enaminones was tested, and the ratio of C-alkylation to N-alkylation was shown to be dependent on the nature of the aromatic substituent. During this work, new hexahydrocarbazolones were synthesized, with substituents on the A ring or the modified C ring. Keywords: photocyclization, aryl enaminones, indole alkaloids, hexahydrocarbazolones-4, cyclopenta[b]indoles.

Letter Open Access

Keywords: β’-amino-α,β-unsaturated ketones; Horner–Wadsworth–Emmons reaction; stereoselective syn... more

An ethnobotanical and phytochemical study of the African medicinal plant Guiera senegalensis J. F. Gmel

Journal of Medicinal Plants Research, 2011

The Sudano-Sahelian species Guiera senegalensis J. F. Gmel. is a small shrub found mainly in West... more The Sudano-Sahelian species Guiera senegalensis J. F. Gmel. is a small shrub found mainly in West Africa. It is well known in the Sahel, where it grows gregariously, forming abundant single-species colonies on fallow clay or sandy soils. Its widespread use in traditional medicine prompted us to conduct an ethnobotanical survey and phytochemical screening of this plant. The chemical analysis tests we carried out confirmed the results of earlier work. The main classes of secondary metabolites, namely anthraquinones, terpenoids, saponins, alkaloids, coumarins, mucilages, flavonoids, tannins, and cardiotonic and cyanogenic heterosides were assayed in different organs of the plant: leaves, fruits, and root and stem bark. New uses of different parts of G. senegalensis by the traditional medical practitioners were recorded especially the use of decoctions of leaves to relieve abdominal pain and migraines. The further investigation of the potentially active constituents of G. senegalensis s...

Anti-Inflammatory and Cytotoxic Potential of New Phenanthrenoids from Luzula sylvatica

Molecules, 2020

Phenanthrenoids have been widely described, in the Juncaceae family, for their biological propert... more Phenanthrenoids have been widely described, in the Juncaceae family, for their biological properties such as antitumor, anxiolytic, anti-microbial, spasmolytic, and anti-inflammatory activities. The Juncaceae family is known to contain a large variety of phenanthrenoids possessing especially anti-inflammatory and cytotoxic properties. Luzula sylvatica, a Juncaceae species, is widely present in the Auvergne region of France, but has never been studied neither for its phytochemical profile nor for its biological properties. We investigated the phytochemical profile and evaluated the potential anti-inflammatory activities of L. sylvatica aerial parts extracts. A bioassay-guided fractionation was carried out to identify the most active fractions. Nine compounds were isolated, one coumarin 1 and eight phenanthrene derivatives (2–9), including four new compounds (4, 5, 8 and 9), from n-hexane and CH2Cl2, fractions. Their structures were established by HRESIMS, 1D and 2D NMR experiments. T...

$Figure 1. ROS production of blood leucocytes, incubated with the methanolic extract or fractions (10, 25 and 50 ug/mL) and stimulated with PMA (1 uM) for 1h. Values are expressed as percentage of the control (cells incubated with PMA and without extract). Data are shown as means + SEM (n = 3-6); * p < 0.05 compared with Control. All results are expressed as a percentage, with control (i.e., cells with PMA but without extract) normalized as 100%.$

$Figure 2. Isolated compounds from CH2Cly and n-hexane fractions. n-hexane fraction was first purified by steric exclusion method using biobeads, then by column chromatography. Six major compounds were isolated, juncunol (3) [23], juncuenin A (6), dehydrojuncuenin A (7) [26] and three new compounds (5, 8, and 9), with original phenanthrene structures, were identified.$

$Figure 3. Key COSY, HMBC and NOESY correlations for compounds 4, 5, 8 and 9. -2. The 'H and °C NMR data showed the presence an aldehyde function with the corresponding arbon at dc 193.5 ppm (CH) and a singlet proton at 64 10.07 ppm. As previously reported in terature [28-30], the aldehyde function was located on C-5. This was confirmed by the HMBC orrelations from H-12 (64 10.07) to C-6 (6¢ 127.2). The position of all the substituents and 1e chemical shifts of all the protons and the carbons were attributed using HMBC and COSY orrelations as described on Figure 3. The structure of the new compound 9 was determined as -hydroxy-1,7-dimethyl-9,10-dihydrophenanthrene-5-carbaldehyde, named sylvaticin C. The nine isolated compounds were tested on leucocytes ROS production as described above for the five fractions. Four of them inhibited ROS production significantly in a dose-dependent manner: compounds 2, 4, 8, and 1 (Figure 4), although the last one had to be tested at higher concentration to be effective.$

Stereoselective strategies for the construction of polysubstituted piperidinic compounds and their applications in natural products’ synthesis

Organic Chemistry Frontiers, 2017

An abridged and far-reaching review communication on the construction of the polysubstituted pipe... more

Advances in tetrahydropyrido[1,2-a]isoindolone (valmerins) series: Potent glycogen synthase kinase 3 and cyclin dependent kinase 5 inhibitors

European journal of medicinal chemistry, Jan 27, 2015

An efficient synthetic strategy was developed to modulate the structure of the tetrahydropyridine... more An efficient synthetic strategy was developed to modulate the structure of the tetrahydropyridine isoindolone (Valmerin) skeleton. A library of more than 30 novel final structures was generated. Biological activities on CDK5 and GSK3 as well as cellular effects on cancer cell lines were measured for each novel compound. Additionally docking studies were performed to support medicinal chemistry efforts. A strong GSK3/CDK5 dual inhibitor (38, IC50 GSK3/CDK5 32/84 nM) was obtained. A set of highly selective GSK3 inhibitors was synthesized by fine-tuning structural modifications (29 IC50 GSK3/CDK5 32/320 nM). Antiproliferative effects on cells were correlated with the in vitro kinase activities and the best effects were obtained with lung and colon cell lines.

A β,β′-ketoaminoester as a valuable tool for the asymmetric construction of substituted homopipecolic esters: application to a formal synthesis of (+)-Calvine

Tetrahedron: Asymmetry, 2004

A highly diastereoselective 1,4-addition involving Davies' lithium amide is employed as the key r... more A highly diastereoselective 1,4-addition involving Davies' lithium amide is employed as the key reaction to prepare, in five steps from ethyl acetoacetate, an enantiomerically pure keto protected b,b 0-ketoaminoester. This latter was reacted with aldehydes in an intramolecular Mannich process and furnished a direct and stereoselective access to substituted homopipecolates. The validity of this approach was achieved through a new formal asymmetric synthesis of alkaloid (þ)-Calvine.

Diastereoselective elaboration of 2,3,4-substituted piperidines using diene iron tricarbonyl complexes. Total synthesis of (±)-dienomycin C and (±)-4-epi-dienomycin C

Tetrahedron Letters, 1996

The diastereoselective formation of 2,3,4-substituted piperidines is achieved by condensation of ... more

Simple pyridylmethylamines: efficient and robust N,N-ligands for Suzuki–Miyaura coupling reactions

Tetrahedron Letters, 2010

... 27 July 2010 Accepted Date: 28 July 2010 Please cite this article as: Gunawan, MA., Qiao, C.,... more

N-Heterocyclic Pyridylmethylamines: Synthesis, Complexation, Molecular Structure, and Application to Asymmetric Suzuki–Miyaura and Oxidative Coupling Reactions

Organometallics, 2011

Acetyl-d3 Chloride: A Convenient Nonchiral Derivatizing Agent (NCDA) for a Facile Enantiomeric Excess Determination of Amines through Deuterium NMR

The Journal of Organic Chemistry, 1996

Chiral resolution of functionalized piperidine enantiomers by capillary electrophoresis with native, alkylated and anionic β-cyclodextrins

Journal of Chromatography A, 1998

Anionic sulfobutylether-b-CD (SBE-b-CD) has been found to be more suitable and convenient than na... more Anionic sulfobutylether-b-CD (SBE-b-CD) has been found to be more suitable and convenient than native or alkylated b-CDs for the enantiomeric separation of functionalized piperidines. This anionic cyclodextrin derivative facilitates the separation of cationic enantiomers since the mobility of the complexed form is opposed to that of the free cation. The addition of low concentrations of SBE-b-CD (5-20 mg / ml) to the phosphate buffer, pH 2.6, allows a fast and baseline separation of dienomycine C (R 51.70) and also of 4-protected 2-alkylated piperidine (R 51.26) into their enantiomers. s s Compared to neutral CDs, this chiral selector offers the benefits of an increased aqueous solubility and a better resolution because this anionic CD acts as a countermigrating complexing agent versus cationic drugs.

A Simple Stereoselective Route to α-Trifluoromethyl Analogues of Piperidine Alkaloids

European Journal of Organic Chemistry, 2006

ABSTRACT The highly diastereoselective synthesis of five trifluoro-substituted analogues of mono-... more ABSTRACT The highly diastereoselective synthesis of five trifluoro-substituted analogues of mono-, di-, and trisubstituted piperidine alkaloids was accomplished in two to four steps from 2-trifluoromethyl keto-protected 4-piperidones, prepared by an intramolecular Mannich-type reaction methodology. A simple stereoselective elaboration of new 2-(trifluoromethyl)-4-piperidinols and 4-amino-2-(trifluoromethyl) piperidines is also described. ((c) Wiley-VCH Verlag GmbH &amp; Co. XGaA, 69451 Weinheim, Germany, 2006)

Efficient synthesis of β’-amino-α,β-unsaturated ketones

Beilstein Journal of Organic Chemistry, 2013

A general and simple procedure to access chiral β'-amino-α,β-enones, in seven steps, from an ... more A general and simple procedure to access chiral β'-amino-α,β-enones, in seven steps, from an α,β unsaturated ester has been described. The use of a Horner–Wadsworth–Emmons reaction as a key step for generating the β'-amino-α,β-enones, permits access to a range of substrates under mild conditions and in moderate to high yield.

Synthesis of 2-thioxoimidazolin-4-one and thiazolo[3,2-a]-benzimidazole derivatives from substituted maleimides

Arkivoc, 2010

We describe here a hetero Michael-type reaction, involving maleimides and 2cyanoacetichydrazide o... more We describe here a hetero Michael-type reaction, involving maleimides and 2cyanoacetichydrazide or 2-mercaptobenzimidazole, followed by an opening cyclization reaction with isothiocyanates. This reaction allows the preparation of new 2-thioxoimidazolidin-4-one and thiazolo[3,2-a]benzimidazole derivatives depending on the nucleophile used.

Diastereoselective preparation of cyclic β-aminoketals. Application to the total synthesis of piperidine alkaloids

Arkivoc, 2007

We describe here the diastereoselective synthesis of cyclic β-aminoketone derivatives which are v... more We describe here the diastereoselective synthesis of cyclic β-aminoketone derivatives which are very powerful synthons for alkaloid synthesis. They were stereoselectively prepared by condensation of a chiral lithium amide on an α,β-unsaturated ester which possesses a leaving group in ω−position. The usefulness of these compounds was demonstrated through the synthesis of indolizidine 209D, an alkaloid isolated from skin extracts of South American frogs and also in the preparation of allosedridine which has been isolated from Sedum acre.

Photocyclization of ketolactams: a new synthesis of functionalized aza-1-bicyclo[x.y.0] alkanes

Journal of Photochemistry, 1981

Photoreduction d'arylcetones par les amides et les lactames: applications synthetiques

Tetrahedron, 1979

ABSTRACT Benzophenone is photoreduced by lactams and amides. In this reaction the hydrogen atom α... more ABSTRACT Benzophenone is photoreduced by lactams and amides. In this reaction the hydrogen atom α to the lactam nitrogen is abstracted regioselectively, and radical coupling leads to adducts. The reaction is general and comparable to an hydroxyalkylation α to the nitrogen atom. Its quantum yield is 0.13 in the case of N-methyl 2-pyrrolidone in CH3CN or in C6H6. Adducts obtained with acetophenone and p,p&#39;-dimethoxy benzophenone are described. The reduction of adduct 12yields the diphenylethanolamine 22 and 12 is dehydrated to give the enamide 21.

Photocyclisation de N-benzoylenamines. Syntheses de spirocyclohexanes en serie isoquinoleine

Tetrahedron, 1991

Substituted N-benzoylenammes are easily prepared from benzoyl chlorides and cycloalkane carboxald... more

Photocyclization of enaminoesters: Access to 2,3 -dihydroindoles spiroimides

Tetrahedron Letters, 1996

The synthesis of spiroindolines imides 15a,b using a photochemical reaction and their transformat... more

Photocyclization of aryl enaminones. An efficient route to indole alkaloid synthons

Canadian Journal of Chemistry, 1989

The photocyclization of enaminones was extended to aryl enaminones bearing a substituent on the a... more The photocyclization of enaminones was extended to aryl enaminones bearing a substituent on the aromatic moiety. This reaction was studied in order to achieve the synthesis of indole alkaloid synthons. Trials of regioselectivity control were made by using groups with enhanced steric hindrance. The reactivity of secondary enaminones was tested, and the ratio of C-alkylation to N-alkylation was shown to be dependent on the nature of the aromatic substituent. During this work, new hexahydrocarbazolones were synthesized, with substituents on the A ring or the modified C ring. Keywords: photocyclization, aryl enaminones, indole alkaloids, hexahydrocarbazolones-4, cyclopenta[b]indoles.

Letter Open Access

Keywords: β’-amino-α,β-unsaturated ketones; Horner–Wadsworth–Emmons reaction; stereoselective syn... more