| Current
Organic Chemistry
ISSN: 1385-2728
Current Organic
Chemistry
Volume 9, Number 2, January 2005
Contents
Photooxygenation of Heterocycles Pp.109-139
M. Rosaria Iesce, Flavio Cermola and Fabio Temussi
[Abstract] [Full
text article]
Recent Progress in the Synthesis of Quinolines
Pp.141-161
Vladimir V. Kouznetsov, Leonor Y. Vargas Mendez and Carlos
M. Melendez Gomez
[Abstract] [Full
text article]
Bartoli Indole Synthesis Pp.163-178
Renato Dalpozzo and Giuseppe Bartoli
[Abstract] [Full
text article]
One-Pot Glycosylation (OPG) for the Chemical Synthesis
of Oligosaccharides Pp.179-194
Biao Yu, Zunyi Yang and Hongzhi Cao
[Abstract] [Full
text article]
Environmentally Benign Solvents in Organic Synthesis:
Current Topics Pp.195-218
Carlos Kleber Z. Andrade and Luana M. Alves
[Abstract] [Full
text article]
Abstracts
[Back to top]
Photooxygenation of Heterocycles
M. Rosaria Iesce, Flavio Cermola and Fabio Temussi
[Full text
article]
The photooxygenation of heterocycles represents a versatile
and widely accepted tool for introducing oxygenated functions
in a mild, simple and selective way. The review evidences
the synthetic potential of the photooxygenation with particular
attention to the reaction of Type II involving singlet oxygen
in the first electronically excited state (1Δg),
which has been applied to the most studied heterocycles as
furans, thiophenes, pyrroles, oxazoles, imidazoles, indoles,
nitrogen-containing six-membered systems. The singlet oxygenation
of these systems occurs mainly via [4+2] cycloaddition leading
to unstable endoperoxides which, in addition to the classical
transformations of peroxides (reduction, hydrolysis, deoxygenation,
generally performed at low temperature), afford characteristic
rearranged products depending on the heteroatom, substitution
pattern and experimental conditions. 1,2-Oxygen addition can
sometimes compete with the Diels-Alder-type reaction, especially
for pyrroles, imidazoles and indoles. The attention has been
also focused to the oxygenation of some biomolecules as histidine,
triptophan and guanine which play a significant role in biological
processes as photodynamic effects or in the photoinduced deactivation
of nucleic acids.
[Back to top]
Recent Progress in the Synthesis of Quinolines
Vladimir V. Kouznetsov, Leonor Y. Vargas Mendez
and Carlos M. Melendez Gomez
[Full text
article]
New developments in the chemistry of quinoline derivatives
are reviewed. Two general synthetic routes based on the utilization
of mono-substituted or ortho-substituted anilines
are discussed. Their major methods and modifications are analyzed.
[Back to top]
Bartoli Indole Synthesis
Renato Dalpozzo and Giuseppe Bartoli
[Full text
article]
Due to the potent biological activity exhibited by various
indole derivatives, there is a continuous demand for novel
synthetic procedures in this area. In 1989, the reaction of
vinyl magnesium halides with ortho-substituted nitroarenes
was discovered to lead to indoles. In the 1990s, it has attracted
much attention, as it employs simple and readily available
starting materials. This reaction is now frequently reported
as the “Bartoli reaction” or the “Bartoli
indole synthesis” and has rapidly become the shortest
and most flexible route to 7-substituted indoles, as classical
indole syntheses generally fail in their preparation.
The flexibility of Bartoli reaction is great as it can be
extended to heteroaromatic nitro derivatives and can be run
on solid support.
The necessity of an ortho-substituent on the aromatic
ring is the limit of the Bartoli indole synthesis, because
o,o’- unsubstituted nitroarenes follow a completely
different pathway when reacting with vinyl Grignard reagents.
Bromine, however, should be a transient group, which can enforce
the sigmatropic rearrangement, as requested by the mechanism,
and is easily removed. A combination of the two methodologies
can give a significant reduction of steps required for the
preparation of many complex 7-unsubstituted indoles, whose
functions are tolerant to the reaction conditions, but not
to classical indole syntheses.
This review will focus both the use of the Bartoli indole
synthesis as key step in many preparation of complex indoles
and the improvements of the reaction.
[Back to top]
One-Pot Glycosylation (OPG) for the Chemical Synthesis of
Oligosaccharides
Biao Yu, Zunyi Yang and Hongzhi Cao
[Full text
article]
This review provides a comprehensive survey of the “one
pot glycosylation” (OPG) strategy for the chemical synthesis
of oligosaccharides, covering literatures from the first example
reported by Kahne and Raghavan in 1993 through May 2003. The
essence of the OPG is to distinguish the reactivity difference
of a pair of the glycosylation donors or acceptors so as to
carry out two glycosylation steps sequentially without purification
of the first-step coupling product. Accordingly, the literature
reports are grouped based on the major stereoelectronic factors
causing the reactivity differences, those include the “armed-disarmed
effect”, “orthogonality of leaving groups”,
“distinguishable acceptors”, and “the hybrid”.
“The hybrid” OPG procedure takes advantage of
a combination of the reactivity disparity of a set of the
armed-disarmed donors, orthogonal leaving groups, as well
as acceptors so as to proceed three or more steps of glycosylation
sequentially in one pot. Relevant conception and exploitation
of the reactivity differences of the donors and acceptors
in the synthesis of oligosaccharides, which finally evolve
the OPG or advance parallelly, are briefly described at the
beginning.
[Back to top]
Environmentally Benign Solvents in Organic Synthesis: Current
Topics
Carlos Kleber Z. Andrade and Luana M. Alves
[Full text
article]
Organic solvents are extensively used in organic synthesis
and for this reason they are a matter of much concern due
to characteristics such as: high flammability, volatility,
hazardness, and toxicity. Thus the search for environmentally
benign substitutes for organic solvents has recently gained
more attention in view of the increasing importance of Green
Chemistry.
In this review, recent developments in the fields of supercritical
fluids, ionic liquids, low melting polymers (especially PEG),
perfluorinated solvents and water in many types of organic
reactions will be disclosed.
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