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Letters in Organic Chemistry
ISSN: 1570-1786
Letters in Organic Chemistry
Volume 5, Number 6, September 2008
Contents
Development of an AM1 “In Silico Tool
Box” for Enantioselective Free Radical Chemistry of
Chiral Non-Racemic Organostannanes and Organogermanes
Pp. 407-416
Victoria T. Perchyonok
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Access to C-Branched Sugars: Stereoselective
Synthesis of C3-C5-Linked Deoxy Disaccharide and C-Linked
Deoxy Aza Disaccharide Mimetics via a Ring-Closing
Metathesis Protocol Pp. 417-424
Palakodety R. Krishna, Appalashetti Manjuvani, Gannoju
Srinivasulu and Aajit C. Kunwar
[Abstract]
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A Regioselective Synthesis of Aryl Sulfones Using
Graphite/MeSO3
H (GMA) Pp. 425-428
Mona Hosseini-Sarvari
[Abstract] [Purchase
Article]
Glycosidation Reactions of 5-Thioxylopyranosyl Donors
Pp. 429-431
Hideya Yuasa, Youichiro Suga and Hironobu Hashimoto
[Abstract] [Purchase
Article]
An Expedient and Selective Approach Towards Disulfides Using
Sodium Bromate/Sodium Hydrogen Sulfite Reagent Pp.
432-434
Khalid M. Khan, Muhammad Ali, Muhammad Taha, Shahnaz Perveen,
M. Iqbal Choudhary and Wolfgang Voelter
[Abstract] [Purchase
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CuBr2
Catalyzed One-Pot Transprotection of TBDMS Ethers to Acetates/benzoates:
Chemoselective Acetylation of Aliphatic in the Presence of
Aromatic TBDMS Ethers Pp. 435-443
Suchitra Bhatt and Sandip K. Nayak
[Abstract] [Purchase
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Lanthanide(III) Chelates for Selective Solution Phase Labeling
of Biomolecules Pp. 444-449
Janne Ketola, Lassi Jaakkola and Jari Hovinen
[Abstract] [Purchase
Article]
CBr4 Catalyzed Synthesis
of Aryl-14H-dibenzo[a, j] Xanthenes
Under Solvent-free Conditions Pp. 450-454
Bhimapaka C. Raju, D. V. Subrahmanya Pradeep, Polepally
P. Reddy and Janaswamy M. Rao
[Abstract]
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Bi(OTf)3 as Mild,
Efficient and Cost-Effective Catalyst for the Alkylation of
N-Heterocycles with Epoxides Pp. 455-460
Jhillu S. Yadav, Basi V. Subbareddy, Avvaru D. Krishna,
Ailuri R. Reddy and Akkirala V. Narsaiah
[Abstract] [Purchase
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TMSCl-NaI-MeCN Reagent Mediated Simple Two-Step Synthesis
of Phenolic Benzosultams Pp. 461-463
Rui Wang, Fang Fang, Long-Qian Tang and Zhao-Peng Liu
[Abstract] [Purchase
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Michael Reactions of β-Ketoesters
Catalyzed by Yb(NTf2 )3
in the Presence of Water Pp. 464-466
Ichiro Suzuki, Yuko Suzumura and Kei Takeda
[Abstract]
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Simple and Convenient Synthesis of (±)-Bakuchiol
Pp. 467-469
Hongli Chen and Yuanchao Li
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Article]
An Efficient Synthesis of (+/-)-Xanthorrhizol: One Pot Decyanation
and Demethylation Pp. 470-472
Jesús A. Luján-Montelongo, Adrián
Covarrubias-Zúñiga, Moisés Romero-Ortega
and José G. Avila-Zárraga
[Abstract] [Purchase
Article]
Exploration of Molybdenum(V) Chloride as a Lewis Acid Catalyst
in Various C-C Bond Formation Reactions Pp. 473-477
Chada R. Reddy, Nagavaram N. Rao and Ambadi Sudhakar
[Abstract] [Purchase
Article]
A Facile Method for Preparation of Novel Cyclopropanespirohydantoins
Pp. 478-483
Qifeng Zhu, Zaixu Xu, Yongbing Hao, Yuling Xiao, Wenjin
Xu, Xianbing Ke, Hanbing Teng, Lamei Wu,Guofu Qiu, Shucai
Liang and Xianming Hu
[Abstract] [Purchase
Article]
A Simple and High-Yield Route to N-9-purynil-acetic
Acid Derivatives Coupled with Amino Acids Pp. 484-489
Marie-Emmanuelle Million, Sylvie Radix, Sébastien
Marrot, Magali Imbert and Joelle Paris
[Abstract]
[Purchase
Article]
Oxalic Acid Dihydrate: A Reusable and Cost-Effective
Catalyst for the Synthesis of Bis(indolyl)methanes under Solvent-Free
Conditions Pp. 490-494
Minoo Dabiri, Mostafa Baghbanzadeh, Seyedeh C. Azimi,
Shaghayegh Ahmadzadeh-Asl and Reza R. Ardestani
[Abstract] [Purchase
Article]
Silica-Supported Dichlorophosphate Catalyzed
Beckmann Rearrangement and Dehydration of Oximes Under Microwave
Irradiation Pp. 495-501
Zheng Li and Zhong Lu
[Abstract] [Purchase
Article]
Novel Photochromic Spiro[Thioxanthene-Naphthopyrans] with
Faster Bleaching Kinetics Pp. 502-506
Érica F. Silva and Paulo J. Coelho
[Abstract] [Purchase
Article]
Melatonin Receptor Antagonist Luzindole: A Facile
New Synthesis Pp. 507-509
Andrew Tsotinis and Pandelis A. Afroudakis
[Abstract] [Purchase
Article]
Abstracts
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Development of an AM1 “In Silico Tool Box”
for Enantioselective Free Radical Chemistry of Chiral Non-Racemic
Organostannanes and Organogermanes
Victoria T. Perchyonok
The AM1 “in silico tool box” is
capable of correctly predicting the preferred stereochemistry
and the stereoenhancement effects of Lewis acids during free
radical hydrogen transfer reactions for a series of chiral
non-racemic organostannanes to several prochiral radicals.
While other methods overestimate the difference in energy
involved, the accuracy of the predicted magnitude, using the
above-mentioned process, for observed enantioselectivities
of certain cases is noteworthy. The methodology has shown
a remarkable adaptability to various structurally diverse
chiral non-racemic hydrides and given reproducibility of the
trends in enantioselectivity observed by several independent
experimental studies.
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Article]
Access to C-Branched Sugars: Stereoselective Synthesis
of C3-C5-Linked Deoxy Disaccharide and C-Linked Deoxy
Aza Disaccharide Mimetics via a Ring-Closing Metathesis
Protocol
Palakodety R. Krishna, Appalashetti Manjuvani, Gannoju
Srinivasulu and Aajit C. Kunwar
RCM mediated stereoselective synthetic approaches for
the branched C-C disaccharide and its aza analog
via Ring Closing Metathesis protocol are described.
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Article]
A Regioselective Synthesis of Aryl Sulfones Using
Graphite/MeSO3
H (GMA)
Mona Hosseini-Sarvari
A rapid, high yielding and regioselective process has
been developed for the synthesis of aryl sulfones via sulfonation
reactions using a mixture of graphite/MeSO3H.
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Article]
Glycosidation Reactions of 5-Thioxylopyranosyl
Donors
Hideya Yuasa, Youichiro Suga and Hironobu Hashimoto
Glycosidation reactions of 5-thioxylopyranosides were
examined. The reaction of a 1,5-dithioxyloside derivative
with N-iodosuccinimide and trifluoromethanesulfonate
gave ring-opened products, but no glycosylated products. On
the other hand, a 5-thioxylopyranosyl trichloroacetimidate
derivative was found to react with aliphatic alcohols and
a sugar alcohol to give a 5-thio analog of biologically important
β(1,4)xylopyranoside
structures.
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An Expedient and Selective Approach Towards Disulfides Using
Sodium Bromate/Sodium Hydrogen Sulfite Reagent
Khalid M. Khan, Muhammad Ali, Muhammad Taha, Shahnaz Perveen,
M. Iqbal Choudhary and Wolfgang Voelter
Treatment of various aliphatic and functionalized aromatic
thiols with a mixture of sodium bromate/sodium hydrogen sulfite
gave the corresponding disulfides in good yields.
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CuBr2
Catalyzed One-Pot Transprotection of TBDMS Ethers to Acetates/benzoates:
Chemoselective Acetylation of Aliphatic in the Presence of
Aromatic TBDMS Ethers
Suchitra Bhatt and Sandip K. Nayak
A variety of TBDMS ethers were directly transprotected
into their acetates/benzoates with acetyl chloride/benzoyl
chloride in a one-pot procedure using CuBr2
(30 mol%). Chemo-selective transprotection of aliphatic TBDMS
ethers in the presence of aromatic TBDMS ethers was achieved
using 10 mol% of the catalyst. Various sensitive functional
groups such as ketals, ketones, alkenes, allyl and benzyl
ethers were found to be compatible under the reaction conditions.
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Lanthanide(III) Chelates for Selective Solution Phase
Labeling of Biomolecules
Janne Ketola, Lassi Jaakkola and Jari Hovinen
Synthesis of photoluminescent lanthanide(III) chelates
that allow selective solution phase labeling of bioactive
molecules using phosphate elimination, native chemical ligation,
and ´click-chemisty´ is described.
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CBr4 Catalyzed
Synthesis of Aryl-14H-dibenzo[a, j]
Xanthenes Under Solvent-free Conditions
Bhimapaka C. Raju, D. V. Subrahmanya Pradeep, Polepally
P. Reddy
and Janaswamy M. Rao
A convenient procedure has been developed for the synthesis
of heteroaryl, aryl and alkyl 14-[H]-dibenzo [a,j]
xanthenes by one-pot condensation of β-naphthol
with heteroaryl, aryl and alkyl aldehydes in the presence
of CBr4, under solvent free
conditions in very good yields. The catalyst is readily available
and is inexpensive to promote the synthesis of xanthenes.
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Bi(OTf)3 as Mild,
Efficient and Cost-Effective Catalyst for the Alkylation of
N-Heterocycles with Epoxides
Jhillu S. Yadav, Basi V. Subbareddy, Avvaru D. Krishna,
Ailuri R. Reddy and Akkirala V. Narsaiah
Epoxides undergo smooth ring opening with N-heterocyclic
compounds such as indoles and pyrroles in the presence of
a catalytic amount of bismuth triflate under mild conditions
to produce C-alkylated indole and pyrrole derivatives
in high yields with a high regioselectivity. Imidazole and
benzotriazole affords N-alkylated products under
identical conditions.
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TMSCl-NaI-MeCN Reagent Mediated Simple Two-Step Synthesis
of Phenolic Benzosultams
Rui Wang, Fang Fang, Long-Qian Tang and Zhao-Peng Liu
A novel simple two-step synthesis of phenolic benzosultams
is first reported. o-Lithiation of N-Boc-o-toluenesulfonamide
followed by reaction with methoxybenzaldehydes gave carbinol
sulfonamides, which were converted to the cyclic phenolic
compounds via TMSCl/NaI/MeCN reagent mediated sequence
involving N-deprotective cyclization and O-demethylation.
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Michael Reactions of β-Ketoesters
Catalyzed by Yb(NTf2 )3
in the Presence of Water
Ichiro Suzuki, Yuko Suzumura and Kei Takeda
Yb(NTf2)3
catalyzed Michael reactions of β-ketoesters
to α,β-unsaturated
carbonyl compounds more efficiently than did Yb(OTf)3
without any additives in pure water, providing Michael adducts
in moderate to good yields.
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Simple and Convenient Synthesis of (±)-Bakuchiol
Hongli Chen and Yuanchao Li
A simple and convenient synthesis of (±)-bakuchiol
has been developed. The key intermediate was obtained in only
one step from the easily available starting material, citral,
by an 1,4-addition procedure. (±)-Bakuchiol
was finally produced in 4 steps to give 50% overall yield.
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An Efficient Synthesis of (+/-)-Xanthorrhizol:
One Pot Decyanation and Demethylation
Jesús A. Luján-Montelongo, Adrián
Covarrubias-Zúñiga, Moisés Romero-Ortega
and José G. Avila-Zárraga
A new and short total synthesis affording (±)-Xanthorrhizol
in 90% overall yield is described. The method comprises three
steps: 1) C-alkylation of 3-methoxy-4-methyl-benzylcyanide
with 5-iodine-2-methyl-pent-2-ene; 2) C-methylation of the
resulting cyanide; and 3) one-pot decyanation and demethylation
carried out by the action of lithium.
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Exploration of Molybdenum(V) Chloride as a Lewis Acid Catalyst
in Various C-C Bond Formation Reactions
Chada R. Reddy, Nagavaram N. Rao and Ambadi Sudhakar
The catalytic activity of Molybdenum(V) chloride as a
Lewis acid in carbon-carbon bond formation reactions has been
described. The reactions of various substrates viz.
aldehydes, benzyl alcohols, glucals and aminals with carbon
nucleophiles were studied in the presence of MoCl5
as a catalyst. Progress of all the reactions proceeded smoothly
to furnish the corresponding products in good yields.
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A Facile Method for Preparation of Novel Cyclopropanespirohydantoins
Qifeng Zhu, Zaixu Xu, Yongbing Hao, Yuling Xiao, Wenjin
Xu, Xianbing Ke, Hanbing Teng, Lamei Wu,Guofu Qiu, Shucai
Liang and Xianming Hu
A facile synthetic approach to 3’-substituted-5-cyclopropanespirohydantoins
has been developed and used to synthesize some new spirohydantoins.
The key aspect is the preparation of α-carboethoxy
isocyanate basing on Curtius rearrangement, which can be ring-closed
to the expected spirohydantoins after the reaction with various
amines and hydrazines. Interestingly the cyclopropane ring
doesn’t open during the whole process.
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A Simple and High-Yield Route to N-9-purynil-acetic
Acid Derivatives Coupled with Amino Acids
Marie-Emmanuelle Million, Sylvie Radix, Sébastien
Marrot, Magali Imbert and Joelle Paris
A facile route to synthesize amide type N-9-purinyl-acetic
acid derivatives both in guanine and hypoxanthine series is
described. The regioselective alkylation of the 6-chloro-purine
derivatives followed by their conversion into guanine or hypoxanthine
nucleus in mild acidic conditions, are the key steps that
allow the efficient preparation of compounds with an acetic
function coupled with various amino acids.
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Oxalic Acid Dihydrate: A Reusable and Cost-Effective Catalyst
for the Synthesis of Bis(indolyl)methanes under Solvent-Free
Conditions
Minoo Dabiri, Mostafa Baghbanzadeh, Seyedeh C. Azimi,
Shaghayegh Ahmadzadeh-Asl and Reza R. Ardestani
Oxalic acid as a solid organic acid catalyzed the synthesis
of bis(indolyl)methanes by the reaction of indole derivatives
and different carbonyl compounds. All the reactions were performed
at ambient temperature and completely het-erogeneous conditions
and the products were obtained in high yields.
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Silica-Supported Dichlorophosphate Catalyzed Beckmann Rearrangement
and Dehydration of Oximes Under Microwave Irradiation
Zheng Li and Zhong Lu
Silica-supported dichlorophosphate had been proved to
be an efficient, recoverable and reusable catalyst for Beckmann
rearrangement of a variety of ketoximes and dehydration of
various aldoximes in THF under microwave irradiation. This
protocol has advantages of high conversion, high selectivity,
short reaction time, no environmental pollution and simple
work-up procedure.
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Article]
Novel Photochromic Spiro[Thioxanthene-Naphthopyrans] with
Faster Bleaching Kinetics
Érica F. Silva and Paulo J. Coelho
Novel spiro[thioxanthene-naphthopyrans] were prepared
and their photochromic properties in solution investigated
under UV-Vis continuous irradiation. When compared to known
similar naphthopyrans these new compounds showed a significant
bathochromic shift of the maximum wavelength of absorption
and faster ring closure kinetics.
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Melatonin Receptor Antagonist Luzindole: A Facile New Synthesis
Andrew Tsotinis and Pandelis A. Afroudakis
A new, convenient and high yield route to luzindole,
the most commonly used melatonin receptor antagonist, is described.
The new method involves the Sonogashira coupling reaction
between 2-iodoaniline and 3-phenyl-1-propyne followed by cyclisation
of the adduct formed, C-3 indole nitroolefination with 1-(dimethylamino)-2-nitroethylene/TFA,
reduction to the respective tryptamine and finally acetylation.
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