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Current
Organic Chemistry
ISSN: 1385-2728
Current Organic
Chemistry
Volume 10, Number 17, November 2006
Contents
Natural Product Chemistry and Heterogeneous
Catalysis
Guest Editor: Massimo Curini
Editorial Pp.
2143
Synthetic Applications of Nitroalkanes Promoted
by Solid Catalysis: Recent Results Pp. 2145-2169
R. Ballini and A. Palmieri
[Abstract]
Silica Sulfuric Acid and Silica Chloride as Efficient
Reagents for Organic Reactions Pp. 2171-2189
Peyman Salehi, Mohammad Ali Zolfigol, Farhad Shirini and
Mostafa Baghbanzadeh
[Abstract]
Catalytic C–C Bond Formation in Natural
Products Synthesis: Highlights From The Years 2000–2005
Pp. 2191-2225
Bor-Cherng Hong and Roshan Y. Nimje
[Abstract]
Catalytic Oxidative Processes in Steroid Chemistry:
Allylic Oxidation, β-Selective
Epoxidation, Alcohol Oxidation and Remote Functionalization
Reactions Pp. 2227-2257
Jorge A.R. Salvador, Samuel M. Silvestre and Vânia
M. Moreira
[Abstract]
Biomimetic Cyclizations of Functionalized Isoprenoid
Polyenes: A Cornucopia of Synthetic Opportunities
Pp. 2259-2282
Enrico Brunoldi, Marco Luparia, Alessio Porta, Giuseppe
Zanoni and Giovanni Vidari
[Abstract]
Abstracts
[Back to top]
Editorial
The 2006 Natural Product Chemistry and Heterogeneous Catalysis
issue of Current Organic Chemistry contains five
contributions from eminent scientists in different fileds.
The first subject deals with nitroalkanes and their recent
synthetic applications. Their chemistry is reviewed by Ballini
and coworkers. Mohamad Ali Zolfigol and coworkers provide
insights abouth the use of Silica Sulfuric Acid and Silica
Chloride as effficient catalysts in organic synthesis. Both
reviews represent excellent contributions in the field of
heterogeneous catalysis. The other three reviews are focused
on Natural Product Chemistry. Hong and coworkers provide a
novel overview of recent results concerning catalytic carbon-carbon
bond formation in natural product synthesis covering years
from 2000 to 2005. Catalytic oxidative processes in steroid
chemistry is the topic of review by Salvador and coworkers.
Finally Vidari and coworkers review what is currently known
with regard to biomimetic cyclizations of functionalized isoprenoid
polyenes.
I would like to express my sincere thanks to all the authors
for providing these articles and for the fascinating results
described.
Prof. M. Curini
University of Perugia
Dipartimento di Chimica e Tecnologia del Farmaco,
Sezione di Chimica Organica
06123 Perugia
Italy
[Back to top]
Synthetic
Applications of Nitroalkanes Promoted by Solid Catalysis:
Recent Results
R. Ballini and A. Palmieri
Solid catalysis is crucial to chemical technology. Innumerable
chemical reactions are facilitated by this catalytic system
and, in this context, nitroalkanes have been demonstrated
a great reactivity under solid catalysis, especially in the
formation of new carbon-carbon single bond. In fact, aliphatic
nitrocompounds are a valuable source of stabilized carbanions
since the high electron-withdrawing power of the nitro group
provides an outstanding enhancement of the hydrogen acidity
at the ?-position (cf. pKa MeNO2 = 10). Nitronate anions,
that can be generated from nitroalkanes, using a wide range
of bases, act as carbon nucleophiles with common electrophiles
such as aldehydes (Nitroaldol-Henry-reaction), and electron-poor
alkenes (Michael reaction), leading to carbon-carbon bond
formation. In the last few decades several solid catalyses
have been efficiently proposed for the employment of the nitroalkanes
in the latter reactions. Very often the use of nitroalkanes,
combined with solid catalysis, offers the opportunity to perform
the reactions more efficiently, with enhanced chemoselectivity,
high purity, improved yields and without the use of any solvent.
[Back to top]
Silica Sulfuric Acid and Silica Chloride as Efficient
Reagents for Organic Reactions
Peyman Salehi, Mohammad Ali Zolfigol, Farhad Shirini and
Mostafa Baghbanzadeh
Silica sulfuric acid and silica chloride, two silica
based solid acids have been used for various organic functional
group transformations either as reagent or as catalyst. All
reactions have been carried out under mild and heterogeneous
conditions. These reagents were used for C-C, C-N, and C-O
bond formation and cleavage and also deprotection of different
protecting groups. Silica sulfuric acid was recycled in many
cases, and reused. Silica chloride has been used as a starting
material for preparation of some new silica based reagents
with special properties.
[Back to top]
Catalytic C–C Bond Formation in Natural Products
Synthesis: Highlights From The Years 2000–2005
Bor-Cherng Hong and Roshan Y. Nimje
The development of new catalytic reactions for C–C
bond formation has played a significant role in natural products
synthesis. In this article we review catalytic C–C bond
formation with respect to the carbon atoms’ hybridization
and the products formed. The reactions of unusual substrates
and the development of new reaction conditions and catalyst
systems are included. This survey highlights the use of catalysts
in natural products synthesis during the years 2000–2005.
[Back to top]
Catalytic Oxidative Processes in Steroid Chemistry:
Allylic Oxidation, β-Selective
Epoxidation, Alcohol Oxidation and Remote Functionalization
Reactions
Jorge A.R. Salvador, Samuel M. Silvestre and Vânia
M. Moreira
The preparation of steroids containing oxygenated functions
in suitable positions of the steroid nucleus is of great importance
and can be achieved by means of several oxidative processes.
In this paper allylic oxidation, β-selective
epoxidation, alcohol oxidation and remote functionalization
reactions in steroid substrates are reviewed. Focus has been
given to catalytic processes because of their major importance
from the viewpoint of synthetic organic chemistry.
[Back to top]
Biomimetic Cyclizations of Functionalized Isoprenoid
Polyenes: A Cornucopia of Synthetic Opportunities
P
Enrico Brunoldi, Marco Luparia, Alessio Porta, Giuseppe
Zanoni and Giovanni Vidari
The synthetic aspects of biomimetic cyclizations
of isoprenoid polyenes, simulating one of the key steps in
the biosynthesis of terpenoids in living organisms, have been
reviewed, with emphasis on transformations carried out on
carbocyclic systems. These reactions are made possible by
a clever choice of initiating and terminating units of cyclization,
and by introducing suitable functional groups on the acyclic
precursor which can be manipulated after cyclization. Complex
functionalized polycyclic structures are thus assembled with
an efficiency paralleling or even superior that of purely
biochemical processes. In particular, synthetic strategies
towards alkyl and hydroxyl-substituted compounds have been
examined in detail. The last part of the review has been dedicated
to a thorough illustration of carbenium ion initiated polyene
cyclizations, with their synthetic applications and a discussion
of the different mechanisms proposed.
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