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Current Organic Chemistry
ISSN: 1385-2728
Current Organic
Chemistry
Volume 9, Number 17, November 2005
Contents
Cycloaddition, Cycloisomerizations and Related Reactions
of Alkynes Bearing Group 13 or 14 Heteroelements Pp.1699
Vincent Gandon, Corinne Aubert & Max Malacria
[Abstract]
The Favorskii Rearrangement: Synthetic Applications Pp.1713
D. Guijarro & M. Yus
[Abstract]
Versatile Reactivity and Catalytic Effects of Copper(II)
Halides in Organic Syntheses Pp.1737
Ferenc Csende & Géza Stájer
[Abstract]
New Synthetic Methods to 2-Pyridone Rings Pp.1757
Mercedes Torres, Salvador Gil & Margarita Parra
[Abstract]
Small Angle X-Ray Scattering: A Powerful Tool to Analyze
Proteins Conformation in Solution Pp.1781
E. Dainese, A. Sabatucci & I. Cozzani
[Abstract]
Abstracts
[Back to top]
Cycloaddition, Cycloisomerizations and Related Reactions
of Alkynes Bearing Group 13 or 14 Heteroelements
Vincent Gandon, Corinne Aubert & Max Malacria
Cycloaddition and cycloisomerization reactions involving
alkynes grant a rapid access to arenes, cyclic dienes, and
cyclopentenone derivatives. The use of alkynes substituted
by group 13 or 14 heteroelements as partners for such reactions
is an emerging strategy. Indeed, the specific electronic properties
of these heteroelements can play a crucial role for controlling
the chemo- and regioselective outcome of a given reaction.
Moreover, the heteroatoms can be considered as latent functional
groups and would allow for further transformations including
Suzuki-Miyaura or Stille cross-couplings. Both aspects will
be presented in this review.
[Back to top]
The Favorskii Rearrangement: Synthetic Applications
D. Guijarro & M. Yus
This review deals with the applications of the Favorskii
rearrangement in synthetic Organic Chemistry, paying especial
attention to the literature appeared after 1980. The mentioned
rearrangement plays a key role in many total synthesis due
to the fact that important modifications in the structure
of the substrate occur during the process. Skeletal rearrangements
in acyclic systems, leading to highly branched carboxylic
acids and its derivatives, as well as structural changes in
cyclic substrates, which result in ring contraction processes,
are described. Some examples of Favorskii rearrangements in
biosynthetic pathways are also presented.
[Back to top]
Versatile Reactivity and Catalytic Effects of Copper(II)
Halides in Organic Syntheses
Ferenc Csende & Géza Stájer
Copper(II) salts are widely applied for the halogenation
of aromatic and heteroaromatic systems, the hal1737ides. In
coupling reactions, CuCl2 has been used as a catalyst for
the benzylation of aromates, the synthesis of alkanes, and
the preparation of diacetylenes, cyclohexenones and symmetric
biaryls. It has further proved suitable for stereoselective
cyclization to lactones, carbon-nitrogen coupling and lactamization,
and for the simple preparation of aroylaminohydrazones, the
allylic amination of olefins, the carbonylation of alkylamines,
and heterocyclizations to pyrrolidinones, pyridinones, pyrroles
and dihydrofurans. The dehydrogenation of carbocycles and
heterocycles can be used in the synthesis of gibberelic acid,
for the aromatization of oestrogen derivatives and for the
conversion of dihydrouracils to uracils. From tetrahydroisoquinolines,
dihydro derivatives have been formed, while dihydropyridazines
in the presence of Cu(II) salts yield pyridazines. Similarly,
the oxidations of cyclohexane, adamantane and methylcatechol
to benzoquinone, and amines to nitriles have been performed.
The conversion of aldehydes to nitriles and benzyl radical
cyclizations to butyrolactones have been achieved. Protection
and deprotection, and various other Cu(II) halide-mediated
reactions are also discussed.
[Back to top]
New Synthetic Methods to 2-Pyridone Rings
Mercedes Torres, Salvador Gil & Margarita Parra
The synthesis of a substituted 2-pyridone ring is a topical
area of continuing interest due to the number of biologically
active molecules containing this moiety. Over the last decade,
natural compounds with this structure have emerged as potent
antitumor antiviral and 1757ttention, because those compounds
may be studied as a simple model for investigating mechanisms
of some enzymatic reactions or for discerning the behavior
of nucleic acids bases in connection with mutation due to
base mispairing or other mistaken helices. Recent studies
have shown the usefulness of 2-pyridones as intermolecular
connectors between building blocks in material science. Thus,
despite the large number of methods known for their synthesis,
new procedures are continuously being developed. Two main
synthetic approaches can be found in the literature: from
other heterocycles systems or condensation of acyclic systems.
The latter can be further classified depending on the bond
formed in the cyclization step: by C-C or C-N bond generation.
The latter can be subclassified depending on the first condensation
step.
This is a review of new or improved methods for constructing
2-pyridone rings. This article will be restricted to ring
formation, which can be included in the total synthesis of
several compounds with specific biological or material properties.
The pursuit of these properties requires efficient synthetic
routes that allow rapid assembly and variation of multiple
pendant substituents on the heteroaromatic case, which permits
rapid analogsynthesis (RAS) [1].
[Back to top]
Small Angle X-Ray Scattering: A Powerful Tool to Analyze
Proteins Conformation in Solution
E. Dainese, A. Sabatucci & I. Cozzani
In the field of molecular biology and biochemistry in which
structural genomics comes as a complement to genome sequencing,
Small-Angle X-ray Scattering (SAXS) is an experimental technique
that, though not widely known and applied, represents a very
powerful tool in the framework of post-genome structural studies.
The aim of this review is to present a synthetic description
of the basic principles of the theory of SAXS and to discuss
in more detail its applications to the study of different
biological molecules, focusing the attention to the recent
advances in the structural analysis of proteins. These studies
are presently undergoing a spectacular expansion associated
with the development of powerful data analysis software, with
the improvement of the quality of data recorded with synchrotron
radiation, and finally with the increasing availability of
high resolution three-dimensional structures which can constitute
a starting point for the analysis of protein conformations
in solution. The advantage of SAXS with respect to other techniques
in the structural studies of proteins resides in the possibility
of performing the measurements in any desired solvent and
in the ability to follow changes of the protein structure
which may occur as a response to a variety of stimuli: pH
or temperature changes, interaction with small ligands, influence
of substrate analogues, chemical or genetic modifications,
etc. In this review we describe the principles of SAXS and
the most recent methods for data analysis in the field of
structural biology and, finally, we report some examples of
the use of this technique as a powerful tool to the structural
study of proteins in solution. |
