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Letters in Organic Chemistry
ISSN: 1570-1786
Letters in Organic Chemistry
Volume 5, Number 3, April 2008
Substituted Dienols from Palladium Catalyzed Coupling
of Hydroaluminated Enynols with Aryl Iodides Pp.
158-164
Kenneth E. Crook, Jin Nie and Mark E. Welker
[Abstract]
Regioselective Alkylation of Pyrrole with 2 Benzylidenemalononitriles
Catalyzed by Cu(OTf)2 Pp.165-168
Dilek I. Tasgin, Baris Temelli, Arife Yazici,
Sertan Aytac and Canan Unaleroglu
[Abstract]
Regioselective Synthesis of Oxepin and Oxocin Annulated Quinoline
Heterocycles by Ring-Closing Metathesis Pp. 169-173
Krishna C. Majumdar, Pradip Debnath and Abu Taher
[Abstract]
Catalytic Activities of Ln-N Complexes
Pp. 174-190
Luo Mei
[Abstract]
Improved Preparation of Nabumetone by
Raney Ni Catalytic Hydrogenation Pp. 191-193
Fan Yang, Lixin Wang Xianguo Li, Jianfen Shen, Jiyu Wang
and Xiaoqi Yu
[Abstract]
Efficient Acetylation and Boc Protection of Carbohydrates,
Phenols and Amines Pp. 194-201
Pintu Kumar Mandal and Anup Kumar Misra
[Abstract]
New Efficient Method for the Preparation of 2-Aryl-4,6- Dinitroindoles:
Reductive Cyclization of E-1-(2-Azido-4,6 Dinitrophenyl)-2-Arylethenes
Pp. 202-204
Vasily V. Mezhnev, Mikhail D. Dutov and Svyatoslav A. Shevelev
[Abstract]
Synthesis of a Benzo[b]furyl (+)-Norcamphor-Derived
Hydroperoxide: Study of the Activity as an Oxidant in Asymmetric
Epoxidations Pp. 205-208
Alessandra Lattanzi, Giovanna Botta and Arrigo Scettri
[Abstract]
An Efficient Protocol for Henry Reaction Using
Basic Ionic Liquid [bmIm]OH as Catalyst and Reaction Medium
Pp. 209-211
Hui Wu, Fu-ren Zhang, Yu Wan and Ling Ye
[Abstract]
Synthesis of NH-Aziridines from Vicinal Amino
Alcohols Via the Wenker Reaction: Scope and Limitation
Pp. 212-217
Min Zhu, Libo Hu, Ning Chen, Da-Ming Du and Jiaxi Xu
[Abstract]
Sequential Thermal and Catalyzed Claisen Rearrangements
Toward the Synthesis of Thiocoumarin-Annulated Furopyrans
Pp. 218-223
Krishna C. Majumdar, Pradip K. Maji and Amarta
K. Pal
[Abstract]
Microwave Irradiation as a Green Alternative to
Phase Transfer Catalysis: Solid-Liquid Phase Alkylation of
Active Methylene Containing Substrates Under Solvent-Free
Conditions Pp. 224-228
György Keglevich Katalin Majrik, László
Vida and István Greiner
[Abstract]
Synthesis of Melphalan-Gem-Bisphosphonate Conjugation
to Bone Tumors and Study of Affinity to Hydroxyapatite In
Vitro Pp. 229-233
Qinglin Jiang, Li Yang, Li Hai and Yong Wu
[Abstract]
Concise Formal Synthesis of (±)-Shikonin
Via a Highly α-
Regioselective Prenylation of 1, 4, 5, 8 Tetramethoxynaphthalene-2-Carbaldehyde
Pp. 234-236
Li-Ming Zhao, De-Feng Xu, Wen Zhou and Shao-Shun Li
[Abstract]
An Efficient Synthesis of Calix[4]pyrroles Under
Lewis Acid Conditions Pp. 237-239
Itzel Mejía-Farfán, Claudia Contreras-Celedón,
Juidt Aviña Verduzco and Luis Chacón-García
[Abstract]
Asymmetric Synthesis of β-Aminosulfones
Via the Enantioselective Hydrogenation of the Corresponding
β-Ketosulfones
Pp. 240-243
Ridha Touati and Béchir Ben Hassine
[Abstract]
Abstracts
[Back to top]
Substituted Dienols from Palladium Catalyzed
Coupling of Hydroaluminated Enynols with Aryl Iodides
Kenneth E. Crook, Jin Nie and Mark E. Welker
Enynols were hydroaluminated and cross coupled with
aryl iodides. Reduction of the yne portion of the enynol is
a serious side reaction so reaction conditions to minimize
reduction and maximize cross coupling were investigated in
detail.
[Back to top]
Regioselective Alkylation of Pyrrole with 2-Benzylidenemalononitriles
Catalyzed by Cu(OTf)2
Dilek I. Tasgin, Baris Temelli, Arife Yazici,
Sertan Aytac and Canan Unaleroglu
Copper triflate was used as catalyst for the addition
of pyrrole to 2-benzylidenemalononitrile and its substituted
derivatives. 2-Alkylated pyrrole derivatives were regioselectively
obtained in mild reaction conditions. The addition reactions
were found to be highly dependent on the substituents of the
phenyl group.
[Back to top]
Regioselective Synthesis of Oxepin and Oxocin Annulated Quinoline
Heterocycles by Ring-Closing Metathesis
Krishna C. Majumdar, Pradip Debnath and Abu Taher
Regioselective synthesis of oxepin and oxocin annulated quinoline
heterocycles by the combination of Claisen rearrangement and
ring-closing metathesis reaction is described. The ring-closing
metathesis (RCM) and ring-closing enyne metathesis (RCEM)
proceeded smoothly in the presence of Grubbs’ catalyst
A or B in toluene under
nitrogen atmosphere without deactivation of the basic quinoline
nitrogen.
[Back to top]
Catalytic Activities of Ln-N Complexes
Luo Mei
Ln-N complexes are important catalysts for organic synthesis
and polymerization. This review describes the progress on
a series of Ln-N complexes, as well as the recent applications
of these complexes in hydroamination/cyclization, hydrosilylation,
polymerization, hydrophosphination/cyclization, and the Tischenko
reaction.
[Back to top]
Improved Preparation of Nabumetone by
Raney Ni Catalytic Hydrogenation
Fan Yang, Lixin Wang Xianguo Li, Jianfen Shen, Jiyu Wang
and Xiaoqi Yu
Nabumetone is efficiently and economically prepared from
hydrogenation of 3-methoxycarbonyl-4-(6-methoxy-2-naphthyl)
but-3-en-2-one catalyzed by Raney Ni (W-2) under 145.0 psi
H2 at 45°C and subsequent
acid hydrolysis in 88.1% yield and 99% purity (GC). A high
vacuum distillation or rectification purification method is
used to improve the whole qualification of nabumetone.
[Back to top]
Efficient Acetylation and Boc Protection of Carbohydrates,
Phenols and Amines
Pintu Kumar Mandal and Anup Kumar Misra
An efficient acetylation and tert-butoxycarbonylation
(Boc) of carbohydrate derivatives, phenols and amines catalyzed
by tetrabutylammonium bromide is reported. The reaction condition
is applicable to substrates containing acid and base labile
functional groups. In most of the cases yields obtained were
excellent.
[Back to top]
New Efficient Method for the Preparation of 2-Aryl-4,6- Dinitroindoles:
Reductive Cyclization of E-1-(2-Azido-4,6 Dinitrophenyl)-2-Arylethenes
Vasily V. Mezhnev, Mikhail D. Dutov and Svyatoslav A. Shevelev
A new efficient method for the preparation of 2-aryl-4,6-dinitroindoles
based on reductive cyclization of E-2-azido-4,6-dinitrostilbenes
under the action of FeCl3•6H2O
– NaI system – in the CH3CN
media at room temperature has been developed.
[Back to top]
Synthesis of a Benzo[b]furyl
(+)-Norcamphor-Derived Hydroperoxide: Study
of the Activity as an Oxidant in Asymmetric Epoxidations
Alessandra Lattanzi, Giovanna Botta and Arrigo Scettri
Starting from easily available (+)-norcamphor and
according to an established approach, the 2-benzo[b]furyl
hydroperoxide exo-5 was obtained
in 58% overall yield. In order to ascertain the impact of
the modification on the activity of this chiral oxidant, a
study was carried out employing it in the asymmetric epoxidation
of an allylic alcohol and α
, β-enones.
[Back to top]
An Efficient Protocol for Henry Reaction Using Basic Ionic
Liquid [bmIm]OH as Catalyst and Reaction Medium
Hui Wu, Fu-ren Zhang, Yu Wan and Ling Ye
Henry reaction can be accelerated by basic ionic liquid 1-methyl-3-butylimidazolium
hydroxide ([bmIm]OH) as catalyst and reaction medium with
good yields in short time at room temperature. This strategy
is general and works with a broad range of aldehydes. The
recovered [bmIm]OH can be recycled with consistent activity.
[Back to top]
Synthesis of NH-Aziridines from Vicinal Amino Alcohols Via
the Wenker Reaction: Scope and Limitation
Min Zhu, Libo Hu, Ning Chen, Da-Ming Du and Jiaxi Xu
The Wenker reaction is an efficient and practical
method for the synthesis of NH-aziridines from vicinal amino
alcohols. However, some limitation in the application has
been reported. The scope and limitation of the Wenker reaction
were investigated with a series of structurally diverse and
representative vicinal amino alcohols.
[Back to top]
Sequential Thermal and Catalyzed Claisen Rearrangements Toward
the Synthesis of Thiocoumarin-Annulated Furopyrans
Krishna C. Majumdar, Pradip K. Maji and Amarta
K. Pal
Regioselective synthesis of a hitherto unreported thiocoumarin-annulated
furopyran moiety was achieved by the application of Claisen
rearrangement in which a second Claisen rearrangement was
achieved by anhydrous aluminum chloride. The precursor endocyclic
compounds for catalyzed Claisen rearrangement were synthesized
by the thermal [3,3] sigmatropic rearrangement of the corresponding
ether.
[Back to top]
Microwave Irradiation as a Green Alternative to
Phase Transfer Catalysis: Solid-Liquid Phase Alkylation of
Active Methylene Containing Substrates Under Solvent-Free
Conditions
György Keglevich Katalin Majrik, László
Vida and István Greiner
An ecofriendly, microwave (MW) promoted and solventless method
is described for the alkylation of diethyl malonate, ethyl
acetoacetate and ethyl cyanoacetate by a variety of alkyl
halides in the presence of K2CO3.
In the solidliquid phase alkylation of active methylene containing
substrates, it seems to be of general value that the phase-transfer
catalyst, that is an onium salt in the present case, can be
omitted and substituted by MW irradiation promoting the formation
of the potassium salt of the substrate and its transfer to
the organic phase. In certain cases, the use of triethylbenzylammonium
chloride led to the formation of by-products under the conditions
(~160 °C/~12 bar) applied.
[Back to top]
Synthesis of Melphalan-Gem-Bisphosphonate Conjugation
to Bone Tumors and Study of Affinity to Hydroxyapatite In
Vitro
Qinglin Jiang, Li Yang, Li Hai and Yong Wu
To develop a methodology for bone-specific delivery
of drugs, a bone-targeting gem-bisphosphonate was used as
a carrier of drugs. We had synthesized five compounds, which
were a new class of potential bone-targeting reagents for
bone tumors consisting of melphalan linked to a gem-bisphosphonate
moiety through an amide linkage. The conjugates showed a high
affinity to hydroxyapatite in vitro.
[Back to top]
Concise Formal Synthesis of (±)-Shikonin
Via a Highly α-
Regioselective Prenylation of 1, 4, 5, 8-Tetramethoxynaphthalene-2-Carbaldehyde
Li-Ming Zhao, De-Feng Xu, Wen Zhou and Shao-Shun Li
A concise formal synthesis of (±)-shikonin via
a highly α
-regioselective prenylation is achieved. The
novelty of the procedure lies in the introduction of side
chain of shikonin in one step via prenylation of
1, 4, 5, 8-tetramethoxynaphthalene-2-carbaldehyde under mild
conditions without producing any γ-isomer.
[Back to top]
An Efficient Synthesis of Calix[4]pyrroles Under Lewis
Acid Conditions
Itzel Mejía-Farfán, Claudia Contreras-Celedón,
Juidt Aviña Verduzco and Luis Chacón-García
An efficient synthesis of calix[4]pyrroles that uses
soft conditions and bismuth salts, which are relatively nontoxic,
readily available and inexpensive, is described.
[Back to top]
Asymmetric Synthesis of β-Aminosulfones
Via the Enantioselective Hydrogenation of the Corresponding
β-Ketosulfones
Ridha Touati and Béchir Ben Hassine
A series of β-aminosulfones
were synthesized with high enantioselectivities via
a new approach, which combines asymmetric hydrogenation of
β-ketosulfones
and Mitsunobu amination reaction of the corresponding β-hydroxysulfones
with a significant high control of the stereochemistry. |
