|
Current
Organic Chemistry
ISSN: 1385-2728
Current Organic
Chemistry
Volume 11, Number 1, January 2007
Contents
Special Issue on Organophosphorus Chemistry
Guest Editor: György Keglevich
Editorial Pp.
1
The Chemistry of Phosphinic and Phosphinous Acid
Derivatives Containing t-Butyl Group a Single Bulky
Substituent: Synthetic, Mechanistic and Stereochemica Aspects
Pp. 3-15
Józef Drabowicz, Wieslawa Kudelska, Andrzej Lopusinski
and Adrian Zajac
[Abstract] [Full
text article]
Synthesis, Structure and Properties of Crowded
Triarylphosphines Pp. 17-31
Shigeru Sasaki and Masaaki Yoshifuji
[Abstract] [Full
text article]
Recent Advances in the Chemistry of Anellated Azaphospholes
Pp. 33-47
Raj K. Bansal, Neelima Gupta and Surendra K. Kumawat
[Abstract] [Full
text article]
Synthesis of Phosphorus Ligands from Zirconium Reagents.
A Useful Approach Pp. 49-60
Maria Zablocka and Jean-Pierre Majoral
[Abstract] [Full
text article]
Synthesis of Chiral Heterocyclic Phosphines for Application
in Asymmetric Catalysis Pp. 61-106
Jens Holz, Mandy-Nicole Gensow, O. Zayas and Armin Börner
[Abstract] [Full
text article]
The Phosphorus Aspects of Green Chemistry: the Use
of Quaternary Phosphonium Salts and 1,3-Dialkylimidazolium
Hexafluorophosphates in Organic Synthesis Pp. 107-126
György Keglevich, Zoltán Baán, István
Hermecz, Tibor Novák and Irina L. Odinets
[Abstract] [Full
text article]
Abstracts
[Back to top]
Editorial
After the success of the 1st Organophosphorus
(OP) special issue of Current Organic Chemistry consisting
of two parts published back to back it is my pleasure to announce
the 2nd. OP special issue approved by the Editor-in-Chief,
Professor Atta-ur-Rahman and the management of Bentham.
The first three papers cover relatively large molecules, such
as phosphorus-containing cyclodextrins, calixarenes and cyclophanes,
as well as dendrimers. The phosphorus-containing macrocycles
form an important group due to supramolecular host-guest interactions
allowing enantioselective syntheses based on chiral discrimination
and making possible selective extractions and application
as sensors. Phosphorus containing dendrimers represent a marvellous
field involving the features of art and a real architecture.
The next article is on the fragmentation and rearrangements
of α-hydroxyiminoalkylphosphonates.
The generation of metaphosphates is important from the synthetic
point of view as the low-coordinate P-species are efficient
phosphorylating agents; nevertheless the mechanism for the
fragmentation is also of interest.
The rich chemistry of N-vinylic phosphazenes is reflected
in the next contribution, as they can be excellent building
blocks in the synthesis of a variety of acyclic and heterocyclic
compounds.
The issue of stereogenic phosphorus remains an evergreen topic
from the point of view of chirality, especially if it is discussed
in a broader context including tricoordinated-, tetracoordinated-,
pentacoordinated- and hexacoordinated phosphorus.
Two papers cover the chemistry of sterically congested phosphorus
compounds, such as tert-butyl substituted phosphinic- and
phosphinous acid derivatives, as well as crowded triarylphosphines.
The presence of bulky P-substituents is important from stability
and mechanistic points of view, but may bring about advantages
connected with the physical properties of the substrate.
The next three articles fall in the scope of P-heterocyclic
chemistry, but from entirely different approaches. Recent
developments of the family of azaphospholes, that can be regarded
as a modification of the most common P-heterocycles, phospholes,
are discussed. Then an up-to-date method for the synthesis
of P-ligands applying zirconium reagents is shown and this
is followed by the presentation of chiral heterocyclic phosphines
together with asymmetric catalytic applications.
Finally, the phosphorus aspects of green chemistry have been
surveyed. The use of quaternary phosphonium salts and 1,3-dialkylimidazolium
hexafluorophosphates are summarized including the major synthetic
applications.
The 1. Organophosphorus Special Issue has been divided into
two parts published back to back. The six reviews included
in this issue (Part II) have been preceded by six other articles
in Volume 10, Number 18 (Part I). The previous papers are
the following:
Organophosphorus Supramolecular Chemistry; Part 1.
Receptors for Organophosphorus Compounds
by Lukasz Berlicki, Ewa Rudzinska, Piotr Mlynarz
and Pawel Kafarski
Phosphorus-Containing Chiral Macrocycles
by Sergey Cherenok, Jean-Pierre Dutasta and Vitaly Kalchenko
Synthetic Pathways towards Phosphorus Dendrimers and
Dendritic Architectures
by Anne-Marie Caminade, Cedric-Olivier Turrin,
Régis Laurent, Alexandrine Maraval and Jean-Pierre
Majoral
Fragmentations and Rearrangements of α
Hydroxyiminoalkylphosphonates
by Eli Breuer
N-Vinylic Phosphazenes. A Useful Tool for the
Synthesis of Acyclic and Heterocyclic Compounds
by FranciscoPalacios, Domitila Aparicio, Gloria
Rubiales, Concepción Alonso and Jesús M. de
los Santos
Stereogenic Phosphorus
by Robert Engel and JaimeLee I'olani Rizzo
György Keglevich
Department of Organic Chemical Technology
Budapest University of Technology and Economics
H-1521 Budapest
Hungary
[Back to top]
The Chemistry of Phosphinic and Phosphinous Acid
Derivatives Containing t-Butyl Group a Single Bulky
Substituent: Synthetic, Mechanistic and Stereochemica Aspects
Józef Drabowicz, Wieslawa Kudelska, Andrzej Lopusinski
and Adrian Zajac
[Full
text article]
Basic synthetic procedures commonly applied for the preparation
of racemic and optically active phosphinic and phosphinous
acid derivatives containing a t-butyl group as a
single bulky substituent are presented. Mechanistic and stereochemical
aspects of the presented protocols are discussed. Structural
studies, which include the X-ray and vibrational circular
dichroism-based determinations of the absolute configuration
at the stereogenic phosphorus atom and calculations of conformational
equilibria for a few model compounds are also mentioned. The
use of the optically active t-butylphenylthiophosphinic
acid as a chiral solvating agent is illustrated.
[Back to top]
Synthesis, Structure and Properties of Crowded
Triarylphosphines
Shigeru Sasaki and Masaaki Yoshifuji
[Full
text article]
Crowded triarylphosphines have attracted broad interest for
a long time since they have unique structure, properties,
and reactivity. This review article focuses on synthesis,
structure, properties, and application of crowded triarylphosphines
represented by trimesitylphosphine and tris(2,4,6-triisopropylphenyl)phosphine,
which are of interest from contemporary viewpoint of material
science rather than ligands for transition metal catalysis.
Synthesis of the crowded triarylphosphines by reaction of
various aryl organometallic reagents with phosphorus halides,
structures of the crowded triarylphosphines in solid and solution,
redox properties and structure-property relationship, cation
radicals of crowded triarylphosphines, and construction of
the functional molecules carrying crowded triarylphosphines
are described.
[Back to top]
Recent Advances in the Chemistry of Anellated Azaphospholes
Raj K. Bansal, Neelima Gupta and Surendra K. Kumawat
[Full
text article]
Azaphospholes are 6π
aromatic heterocycles incorporating at least one σ2,λ3–phosphorus
atom and one σ2,λ3–nitrogen
atom. This review covers the synthesis, structural characterization,
reactions and theoretical calculations of azaphospholes anellated
to a six– or five–membered heterocyclic ring,
reported during the last 10-12 years. Three synthetic methods,
namely [4+1] cyclocondensation, [3+2] cyclocondensation and
1,5-electrocyclization make a variety of these phosphorus
heterocycles available. The aromatic character of these compounds
has been confirmed by carrying out density functional theory
(DFT) calculations. Mainly 1H, 13C and
31P NMR studies have been employed for the structural
characterization. Almost all the functionalities present in
the azaphosphole ring have been investigated and electrophilic
substitution reactions of the 1-unsubstituted compounds and
Diels-Alder reactions as well as 1,2-addition reactions to
the >C=P– moiety have been accomplished successfully.
The stereo- and regioselectivities observed in the Diels-Alder
reactions have been explained on the basis of DFT calculations.
Cheletropic cycloadducts formed from [4+1] cycloaddition of
o-quinones on the σ2,λ3–P
atom have been obtained. A variety of coordination compounds
formed by σ
-coordination of the σ2,λ3–P
atom have been prepared.
[Back to top]
Synthesis of Phosphorus Ligands from Zirconium Reagents.
A Useful Approach
Maria Zablocka and Jean-Pierre Majoral
[Full
text article]
The use of several zirconium reagents as the Schwartz reagent
[Cp2ZrHCl]n, the dimethylzirconocene
Cp2ZrMe2, the zirconocene [Cp2Zr],
and the diphenylzirconocene Cp2ZrPh2
allows the synthesis of a variety of new linear and cyclic
P-C and P-N ligands. 1,1 diphosphines can be prepared from
unsaturated monophosphines. A useful methodology involving
ring opening reactions permits the preparation of phosphinite-phosphine
and bis-phosphinite ligands. N-functionalized imines and β-diimines
substituted with phosphino groups are obtained from cyanophosphines
or dinitriles. Carbozirconation of chlorophospha-imine leads
to the unprecedented P-metalated iminophosphorane which presents
a versatile reactivity towards electrophiles and small unsaturated
molecules. Constraint three and four phosphorus cycles can
be easily isolated using [Cp2M] (M = Zr or Ti).
Interactions between benzynezirconocene and unsaturated phosphines
afford numerous methods to prepare linear and cyclic phosphorus
reagents. Enantiomerically pure iminophosphines can be synthetized
from phosphinozirconocene complexes.
[Back to top]
Synthesis of Chiral Heterocyclic Phosphines for Application
in Asymmetric Catalysis
Jens Holz, Mandy-Nicole Gensow, O. Zayas and Armin Börner
[Full
text article]
The synthesis of chiral heterocyclic phosphines, such as phosphiranes,
phosphetanes, phospholes and phosphinanes will be reviewed.
These compounds play a pivotal role as ligands and organocatalysts,
respectively, in asymmetric reactions. Synthetic approaches
will be analyzed in the framework of several sub-categories
e.g. the preparation of mono-, bis- and poly(phosphines).
General synthetic strategies for the preparation of large
families of related compounds will be considered such as 1.)
stereoselective
α-alkylation of phosphine oxides or phosphine
boranes, 2.) ring closure by substitution reactions and 3.)
hydrogenations of unsaturated P-heterocylic compounds, followed
by epimerization reactions. Besides these general methodologies
also protocols leading to a single phosphine will be discussed.
In some cases also the preparation of such phosphines will
be presented, which have not yet been used in asymmetric catalysis,
however, which have - owing to their structure - some relevance
to synthetic methodologies or compounds discussed herein.
For most phosphines presented applications in asymmetric catalytic
reactions will be briefly mentioned together with characteristic
enantioselectivities achieved.
[Back to top]
The Phosphorus Aspects of Green Chemistry: the Use
of Quaternary Phosphonium Salts and 1,3-Dialkylimidazolium
Hexafluorophosphates in Organic Synthesis
György Keglevich, Zoltán Baán, István
Hermecz, Tibor Novák and Irina L. Odinets
[Full
text article]
The search for suitable ionic liquids that are non-volatile,
non-toxic, dissolve a variety of reactants and are recyclable
is a real challenge for chemists to be able to replace the
traditional solvents that are volatile, flammable and toxic.
This segment of chemistry has, these days, become a firm part
of green chemistry attracting much attention. The present
review summarizes and critically discusses the data accumulated
in recent years on the synthesis and utilization of phosphorus
containing ionic liquids, such as imidazolium hexafluorophosphates
and phosphonium salts. As regards the preparation of ionic
liquids, the key steps are quaternization and the introduction
of the corresponding anion. Physical properties of the ionic
liquids can be fine-tuned by selecting suitable cation-anion
pairs. The reactions studied in ionic liquids embraces catalytic
hydrogenations, transfer hydrogenations, oxidations, hydroformylations,
carbonylations, alkylations, acylations, nucleophilic substitutions,
halogenations, condensations, Diels-Alder reactions, Michael
additions, coupling reactions and transformations in organophosphorus
chemistry. Ionic liquids are especially suitable to accommodate
catalytic reactions where one of the components is a gas.
Stress was laid to highlight the chemo-, regio-, diastereo-
and, especially, the enantioselectivity of the reactions performed
in ionic liquids. The data on the ecotoxicity of imidazolium
hexafluorophosphates and phosphonium salts are briefly discussed.
|
