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Current
Organic Chemistry
ISSN: 1385-2728
Current Organic
Chemistry
Volume 11, Number 15, October 2007
Contents
Stereoselective Indium-Mediated Allylation Reactions
Pp. 1287-1309
Robert B. Kargbo and Gregory R. Cook
[Abstract]
Recent Advances in the Synthesis of Hydroporphyrins
Pp. 1310-1338
Michal Galezowski and Daniel T. Gryko
[Abstract]
Synthesis of Macrocyclic Compounds by Ring Closing
Metathesis Pp. 1339-1365
K. C. Majumdar, H. Rahaman and B. Roy
[Abstract]
Imidoyl Radicals in Organic Synthesis†
Pp. 1366-1384
Matteo Minozzi, Daniele Nanni and Piero Spagnolo
[Abstract]
Applications and Synthesis of the Antiepileptic Drug
Oxcarbazepine and Related Structures Pp. 1385-1399
M. Carril, R. SanMartin and E. Domínguez
[Abstract]
Abstracts
[Back to top]
Stereoselective Indium-Mediated Allylation Reactions
Robert B. Kargbo and Gregory R. Cook
Since the discovery that indium could affect a Barbier-type
allylation of carbonyls in water over a decade ago, interest
in the utility of indium metal and its salts to influence
organic transformations has increased exponentially. Control
of chemo-, regio-, and especially stereoselectivity in indium-mediated
reactions has proven to be a challenge, however, examples
of such discerning processes are now beginning to appear on
a regular basis. Indium has been found to be effective in
the allylation of carbonyls, carbometallation of some alkenes
and alkynes. It has also been shown to be a reducing agent
for a variety of organic functional groups, mediators for
a variety of coupling reactions, and more recently indium
reagents have been utilized as initiators for radical transformations.
This review presents an overview of the development of stereoselective
indium-mediated organometallic reactions.
[Back to top]
Recent Advances in the Synthesis of Hydroporphyrins
Michal Galezowski and Daniel T. Gryko
The various approaches to the synthesis of hydroporphyrins
are summarized. Transformations of synthetic porphyrins have
been extensively studied in the last decade due to their easy
availability. Many two and three step reaction sequences have
been developed, which have allowed access to a broad variety
of structures including not only chlorins but also benzochlorins,
secochlorins etc. The fact that porphyrins can act as dienophiles
or dipolarophiles has been broadly investigated and utilized.
On the other hand ‘total syntheses’ of chlorins
from pyrrole and other simple starting materials have been
pursued by only a few research groups. Generally a [2+2] approach
has been investigated and usually chlorins possessing two
geminal methyl groups on the reduced pyrrole ring (‘locked’
chlorins) were the targets of the studies. The synthesis of
tetrahydrodipyrrin derivatives as popular building blocks
was the subject of intense investigation. Overall, a few interesting
and ingenious approaches toward ‘total synthesis’
of chlorins were proposed, reaching total yields on the level
of 1-5%. Some derivatives with auxochromic groups were prepared,
which allowed the study of the relationship between structure
and spectroscopic properties. Bacteriochlorin synthesis, probably
due to their limited stability, has been studied less extensively.
[Back to top]
Synthesis of Macrocyclic Compounds by Ring Closing
Metathesis
K. C. Majumdar, H. Rahaman and B. Roy
Synthesis of macrocyclic compounds including natural products
with varying complexities by ring closing metathesis is described.
Twelve to very large rings that have been synthesized in moderate
to good yields and the synthesis of larger rings as a part
of bi- or poly-cyclic systems are also described in this review.
The effectiveness of the Grubbs’ catalyst towards the
RCM in presence of free alcohols, epoxides as well as with
various silyl ethers is also presented. In addition to these,
the application of RCM towards the syntheses of various naturally
occurring macrolides, lactams and unnatural cyclic poly ethers,
catenanes etc. are described.
[Back to top]
Imidoyl Radicals in Organic Synthesis†
Matteo Minozzi, Daniele Nanni and Piero Spagnolo
Imidoyl radicals (R1N=C∞R2)
are very attractive intermediates that can be readily produced
by several methods, i.e. hydrogen atom abstraction from aldimines,
homolytic fragmentation of certain imidoylic precursors, and
addition of both carbon- and heteroatom-centered radicals
to isonitriles and isothiocyanates. As far as their synthetic
potential is concerned, they have been shown to perform smooth
intra- and intermolecular additions to double and triple carbon-carbon
bonds, as well as cyclizations onto aromatic rings, sulfur
atoms, and cyano groups. They have been therefore efficiently
employed in cyclizations, annulations, and cascade reactions
leading to the construction of various nitrogen-containing
heterocyclic compounds, e.g. indoles, phenanthridines, pyrrolidines,
quinolines, quinoxalines, and fused poly-cyclic derivatives.
They have been also used as key intermediates in the synthesis
of carbonyl compounds, amides, and ni-triles and as precursors
of alkyl radicals in tin-free reactions. In this review we
discuss thoroughly the generation methods, the structural
features, and, above all, the reactivity of imidoyl radicals,
with particular attention devoted to their synthetic applications.
[Back to top]
Applications and Synthesis of the Antiepileptic Drug
Oxcarbazepine and Related Structures
M. Carril, R. SanMartin and E. Domínguez
Oxcarbazepine (OXC), the active ingredient of Trileptal®
(Novartis Pharma), has become the most widely prescribed drug
for the treatment of epilepsy and other CNS diseases, due
to its improved side-effect profile and relevant anticonvulsant
activity compared to the parent drug, carbamazepine (CBZ).
Given its importance and well-established therapeutic applications,
much effort has been devoted to the improvement of its original
synthetic protocol, searching for shorter, milder and more
efficient routes, employing not only classical transformations
but also modern synthetic tools, such as palladium-catalysed
arylation reactions. In this article it is intended to resume
the applications and features of OXC as an anticonvulsant
drug, as well as to compile for the first time all the reported
routes to OXC, from the originally-developed protocol to the
latest methodology, which allowed for the synthesis of a family
of structural analogues. Such synthetic sequences will be
discussed and comprehensively classified according to whether
the approach to OXC is based on either modifications on the
iminodibenzyl ring or coupling reactions.
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