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Letters in Organic Chemistry
ISSN: 1570-1786
Letters in Organic Chemistry
Volume 4, Number 3, April 2007
Oxidation of Baccatin III at C14: A Facile Rearrangement
of the Baccatin III Core Pp. 151-154
Dinah Dutta, Apurba Datta, David G. Vander Velde and Gunda
I. Georg
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Stereoselective Addition of Chiral Oxazoline
Cyanocuprates to Conjugated Nitroalkenes Pp. 155-157
Francisco A. Marques, Davi C. Silva, Edison P. Wendler,
Celso L. Wosch, Quezia B. Cass and Fabiana Batigalhia
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Synthesis of Novel Chiral Ammonium-Based Ionic Liquids
Derived from Isosorbide and their Applications in an Asymmetric
Aza Diels-Alder Reaction Pp. 158-167
Olivier Nguyen Van Buu and Giang Vo-Thanh
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Synthesis of Asymmetric Peptide Mimetic Compounds
Containing Tartaric Acid Core. Potential Inhibitors of HIV-1
Protease Pp. 168-171
Gabriel O. de Resende, Lucia C.S. Aguiar, Bruno A. Cotrim,
João F.C. da Silva and O.A.C. Antunes
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New BINOL Schiff Base as a Tridentate Ligand for Catalytic
Asymmetric Addition of Diethylzinc to Aldehydes in the Presence
of Titanium Tetraisopropoxide Pp. 172-174
Bing Liu, Cao Fang, Zhi-Bing Dong and Jin-Shan Li
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First Immobilization of Chiral Menthol-Derived Picoline
on Solid Support and Evaluation for Asymmetric Catalysis
Pp. 175-180
Philippe Pierrat, Yves Fort and Philippe C. Gros
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The Copper(I) Chloride-Catalyzed Reaction of Ketene
Silyl Acetals or Silyl Enol Ethers with α-Halogen
Substituted Allylsilanes to Form Carbonyl Compounds Bearing
Vinylsilane Functionality Pp. 181-184
Michiharu Mitani and Masayuki Masuda
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Synthesis and Photophysical Properties of a Star-Shaped
Fluorescent Phosphane Sulfide Pp. 185-188
Minh-Huong Ha-Thi, Vincent Souchon, Maël Penhoat,
Fabien Miomandre, Jean-Pierre Genêt, Isabelle Leray
and Véronique Michelet
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Synthesis and Cytotoxic Activity of Steroidal Phosphorothioate,
Phosphoroselenoate, and Phosphate Derivatives Conjugated with
3’-Azido-3’-Deoxythymidine Pp. 189-192
Peiyuan Jin, Sanhao Ji, Yong Ju and Yufen Zhao
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Synthesis of New Halo-Containing Enynes: Reaction
of Lithium Acetylenides with 1,1,1-Trihalo-4-alkoxy-3-buten-2-ones
Pp. 193-197
Marcos A.P. Martins, Marcelo Rossatto, Clarissa P. Frizzo,
Pablo Machado, Lucas Pizzuti, Daniel Emmerich, João
I. Pereira, Sergio Brondani, Nilo Zanatta, Helio G. Bonacorso
and Alex F.C. Flores
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Synthesis of New 4-(3,4,5-Trimethoxyphenyl)-3H-Furo[3,4-b]
Carbazole-3-Ones Derivatives Pp. 198-202
Aurélie Chilloux, Bérenger Biannic, Fabien
Girault, Maud Antoine,
Sylvain Routier and Jean-Yves Mérour
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Synthesis of Novel 5,6,7-Substituted 3-Phenyl-6,7
Dihydroisoxazolo [4,5-d]Pyrimidines Pp.
203-211
S.B. Aliabiev, I.S. Ivanov, A.P. Ilyin, D.V. Kravchenko
and A.V. Ivachtchenko
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Structure-Activity Relationship of Acetylcholinesterase
Reactivators – Antidotes Against Nerve Agents
Pp. 212-217
Kamil Kuca, Veronika Racakova, Daniel Jun and Jiri Bajgar
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Nanoclay-Catalyzed Tandem Conjugate Addition-Annulation
Protocol for Imidazo-1,3-Thiazines Pp. 218-221
Lal Dhar Singh Yadav and Ritu Kapoor
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Synthesis of Some Spirochroman-4-Ones by Regioselective
[4+2] Cycloaddition Reactions Pp. 222-227
Moheddine Askri, Mohamed Rammah, Karin Monnier-Jobé,
Kabula Ciamala, Michael Knorr and Carsten Strohmann
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Oxidation of Baccatin III at C14: A Facile
Rearrangement of the Baccatin III Core
Dinah Dutta, Apurba Datta, David G. Vander Velde and Gunda
I. Georg
Modifications at the largely unexplored C14 position
of the baccatin III core of the taxanes were carried out.
Oxidation at C14 of 7-TES-13-ketobaccatin III with benzeneseleninic
anhydride resulted in novel A, B ring rearranged products.
A probable mechanism for product formation and reductive transformations
of the rearranged products are described.
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Stereoselective Addition of Chiral Oxazoline
Cyanocuprates to Conjugated Nitroalkenes
Francisco A. Marques, Davi C. Silva, Edison P. Wendler,
Celso L. Wosch, Quezia B. Cass and Fabiana Batigalhia
Chiral oxazoline cyanocuprates were prepared and added to
conjugated nitroalkenes. Stereoselectivity up to 80% was achieved
with the cuprate prepared from the chiral oxazoline derived
from (S)-Phenylalaninol.
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Synthesis of Novel Chiral Ammonium-Based Ionic Liquids
Derived from Isosorbide and their Applications in an Asymmetric
Aza Diels-Alder Reaction
Olivier Nguyen Van Buu and Giang Vo-Thanh
A novel family of chiral ammonium-based ionic liquids containing
a chiral moiety and a free hydroxyl function has been designed
and synthesized from isosorbide. The synthesis of these ionic
liquids is easy and practical owing to the commercially available
starting materials. These new chiral ionic liquids can be
used as chiral reaction media as well as catalysts in asymmetric
synthesis, which are currently being investigated in our laboratory.
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Synthesis of Asymmetric Peptide Mimetic Compounds
Containing Tartaric Acid Core. Potential Inhibitors of HIV-1
Protease
Gabriel O. de Resende, Lucia C.S. Aguiar, Bruno A. Cotrim,
João F.C. da Silva and O.A.C. Antunes
Dihydroxyethylene containing compounds, envisaged as aspartic
protease inhibitors (cores), were easily synthesized in few
steps, by a sequence involving ring opening of diacetyl tartaric
anhydride, peptide coupling and de-esterification under basic
conditions affording the desired diols in a simple and inexpensive
method.
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New BINOL Schiff Base as a Tridentate Ligand for Catalytic
Asymmetric Addition of Diethylzinc to Aldehydes in the Presence
of Titanium Tetraisopropoxide
Bing Liu, Cao Fang, Zhi-Bing Dong and Jin-Shan Li
We have developed three new chiral 3-substituted BINOL Schiff
base ligands for the asymmetric diethylzinc addition to aldehydes
in the presence of titanium tetraisopropoxide. The reaction
provided optically active second alcohols in high yield and
moderate enantioselectivity (up to 67% ee).
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First Immobilization of Chiral Menthol-Derived Picoline
on Solid Support and Evaluation for Asymmetric Catalysis
Philippe Pierrat, Yves Fort and Philippe C. Gros
The first polystyrene-supported chiral picolyl menthol has
been prepared via a selective hydrosilylation route
and evaluated for asymmetric catalysis. The new catalyst was
efficient and reusable in the test reaction of diethylzinc
addition to benzaldehyde at room temperature. The enantioselectivity
was comparable with that of the soluble counterpart.
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The Copper(I) Chloride-Catalyzed Reaction of Ketene
Silyl Acetals or Silyl Enol Ethers with α-Halogen
Substituted Allylsilanes to Form Carbonyl Compounds Bearing
Vinylsilane Functionality
Michiharu Mitani and Masayuki Masuda
The CuCl-catalyzed reaction of (1-bromo-2-propenyl)trimethylsilane
with silyl enol ethers or ketene silyl acetals in a CH3CN
solution was studied. A new method for the preparation of
ketone and ester derivatives bearing a vinylsilane functionality
at the γ-position
was developed.
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Synthesis and Photophysical Properties of a Star-Shaped
Fluorescent Phosphane Sulfide
Minh-Huong Ha-Thi, Vincent Souchon, Maël Penhoat,
Fabien Miomandre, Jean-Pierre Genêt, Isabelle Leray
and Véronique Michelet
The synthesis of a new push-pull fluorophore containing phosphane
sulfide derivative was realized via organophosphorous
reaction and Sonogashira cross-coupling reaction. This molecule
exhibits high fluorescence quantum yields and large Stokes
shift in polar solvents.
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Synthesis and Cytotoxic Activity of Steroidal Phosphorothioate,
Phosphoroselenoate, and Phosphate Derivatives Conjugated with
3’-Azido-3’-Deoxythymidine
Peiyuan Jin, Sanhao Ji, Yong Ju and Yufen Zhao
Some steroidal phosphorothioate, phosphoroselenoate, and phosphate
derivatives conjugated with 3’-Azido-3’-deoxythymidine
(AZT) have been synthesized in good yields and their structures
were confirmed on the basis of spectral methods. The result
has shown that some of bioconjugates possess activity against
breast cancer MCF-7 in bioassay.
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Article]
Synthesis of New Halo-Containing Enynes: Reaction
of Lithium Acetylenides with 1,1,1-Trihalo-4-alkoxy-3-buten-2-ones
Marcos A.P. Martins, Marcelo Rossatto, Clarissa P. Frizzo,
Pablo Machado, Lucas Pizzuti, Daniel Emmerich, João
I. Pereira, Sergio Brondani, Nilo Zanatta, Helio G. Bonacorso
and Alex F.C. Flores
The reaction of lithium acetylenide ((R–C?CLi, where
R = Ph, Pent, Bu) with 1,1,1-trihalo-4-alcoxy-3-alken-2-ones
[CX3C(O)C(R2)=C(R1)–OR3,
where X = Cl, F; R1, R2
= H, Me; R3 = Me, Et] in
the presence of BF3•Et2O
to give 1,4- or 1,2-addition products is reported. The regiospecific
formation of 1,4-addition products was observed for substrates
with R1 = H, and for substrates
which had the methyl group on C-4 (R1
= Me), the formation of 1,2-addition products was favored.
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Synthesis of New 4-(3,4,5-Trimethoxyphenyl)-3H-Furo[3,4-b]
Carbazole-3-Ones Derivatives
Aurélie Chilloux, Bérenger Biannic, Fabien
Girault, Maud Antoine,
Sylvain Routier and Jean-Yves Mérour
New 1,5-Dihydro-4-(3,4,5-trimethoxyphenyl)-3H-furo[3,4-b]carbazol-3-ones
were synthesized via a key Diels-Alder reaction under
microwave irradiation. Two routes were investigated to generate
the dienoic precursors. Both started from 3-formylindole,
which was used in a six steps synthesis to obtain the complex
heterocycle. The use and removal of indolic protective groups
such as t-Boc and benzenesulfonyl have been studied.
The Diels-Alder reaction generating the carbazole ring was
optimised under either thermal conditions or microwave irradiation.
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Synthesis of Novel 5,6,7-Substituted 3-Phenyl-6,7
Dihydroisoxazolo [4,5-d]Pyrimidines
S.B. Aliabiev, I.S. Ivanov, A.P. Ilyin, D.V. Kravchenko
and A.V. Ivachtchenko
In this work we present a convenient synthetic route to novel
5,6,7-substituted 3-phenyl-6,7 dihydroisoxazolo[4,5-d]pyrimidines.
The key synthetic step is based on the cyclization of 4-amino-3-phenylisoxazole-5-carboxamides
and ethyl 4-[(ethoxymethylene)amino]-3-phenylisoxazole-5-carboxylates.
The developed methodology can be easily adapted to high-throughput
combinatorial format.
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Structure-Activity Relationship of Acetylcholinesterase
Reactivators – Antidotes Against Nerve Agents
Kamil Kuca, Veronika Racakova, Daniel Jun and Jiri Bajgar
Organophosphorus nerve agents such as sarin, cyclosarin or
tabun are substances originally developed for military purposes.
These compounds are able to inhibit an enzyme acetylcholinesterase
(AChE; EC 3.1.1.7) via phosphorylation in its active
site. AChE reactivators and anticholinergics are generally
used as antidotes in the case of intoxication with these agents.
In this work, reactivation potency of twenty-one structurally
different AChE reactivators was tested in vitro and
subsequently, relationship between their chemical structure
and biological activity was described. Cyclosarin as an appropriate
member of the nerve agents family was chosen to illustrate
these relationships.
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Nanoclay-Catalyzed Tandem Conjugate Addition-Annulation
Protocol for Imidazo-1,3-Thiazines
Lal Dhar Singh Yadav and Ritu Kapoor
A nanoclay-catalyzed atom and energy-efficient low hazardous
tandem conjugate addition-cyclodehydration of cyclic thioureas
(ethylenethiourea and 2-mercaptoimidazole/-benzimidazole)
with dielectrophiles (chalcones) readily annulates a 1,3-thiazine
ring on imidazoles to yield 7H-imidazo[2,1-b]-1,3-thiazines
under solvent-free microwave irradiation in a one-pot procedure.
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Synthesis of Some Spirochroman-4-Ones by Regioselective
[4+2] Cycloaddition Reactions
Moheddine Askri, Mohamed Rammah, Karin Monnier-Jobé,
Kabula Ciamala, Michael Knorr and Carsten Strohmann
Synthesis of several spiro[4-aryl-5-hydroxy-2-(1-isoquinolinyl)-5-phenyl-4,5-dihydro-3H-pyrrole-3,3’-3H-chroman-4’-ones]
has been accomplished in satisfying yields by regioselective
[4+2] cycloaddition reaction of a 2-benzoyl-1,2-dihydroisoquinoline-1-carbonitrile
tetrafluoroborate salt across (E)-3-arylidene-4-chromanones.
The spirocompounds evolve to pyrroles after acidic hydrolysis.
The crystal structure of (10c) has been determined
by an X-Ray study diffraction.
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