Current Organic Chemistry, Volume 7, No. 14, 2003
The Retro Diels-Alder Reaction as a Valuable
Tool for The Synthesis of Heterocycles Pp.1423-1432
Geza
Stajer, Ferenc Csende and Ferenc Fulop
Naturally Occurring Diazo Compounds: The
Kinamycins Pp.1433-1442
Jose
Marco-Contelles , and Maria T. Molina
The Paternò-BÜchi Reaction on Furan
Derivatives Pp.1443-1459
M.
D’Auria , L. Emanuele, R. Racioppi and G. Romaniello
Chemistry of Bis-Spiroacetal Systems: Natural
Products, Synthesis and Stereochemistry Pp.1461-1484
Margaret
A. Brimble and Daniel P. Furkert
Carboxylate Binding by Guanidiniocarbonyl
Pyrroles: From Self- Assembly to Peptide Receptors Pp.1485-1502
Carsten
Schmuck , Lars Geiger
Abstracts
[Back to top] The Retro Diels-Alder Reaction as a Valuable
Tool for The Synthesis of Heterocycles
Geza
Stajer, Ferenc Csende and Ferenc Fulop
Applications of
the retro Diels-Alder reaction (cycloreversion) under mild conditions for the
laboratory preparation of heteromonocycles or condensed-ring heterocycles are
reviewed. A new method utilizes diendo- or diexo-3-aminonorbornene-2-carboxylic
acids and their derivatives for the formation of heterocyclic ring systems
which are difficult to access by other routes or which can be prepared only in
complicated multi-step procedures. The synthesis of substituted 1,3-dienes
(e.g. furan derivatives) and O,N- or N,N-heterocycles (oxazoles, isoxazoles,
pyrazoles, imidazoles, triazoles, pyrimidinones, oxazinones, pyridazinones etc)
are discussed.
[Back to top] Naturally Occurring Diazo Compounds: The
Kinamycins
Jose
Marco-Contelles , and Maria T. Molina
In this account we
will present and critically analyze the different synthetic strategies that
have been reported in the literature for the synthesis of kinamycin C, one the
rare naturally occurring diazo compounds, with interesting biological
activities.
[Back to top] The Paternò-Büchi Reaction on Furan
Derivatives
M.
D’Auria , L. Emanuele, R. Racioppi and G. Romaniello
The Paternò-Büchi
reaction on furan derivatives is reviewed. The photochemical reaction of furan
derivatives in the reaction with carbonyl compounds gives the corresponding
monoadduct with high regio- and stereoselectivity. When the reaction is carried
out in benzene, a large amount of the diadduct can be obtained. The exo
stereoselectivity at C-6 was explained assuming the presence of a secondary
orbital effect on spin orbit coupling. Regio- and stereoselectivity of the
reaction of carbonyl compounds with 2,3-dihydrofuran is described. Applications
of the reaction to the synthesis of 2- and 3-furylmethanol derivatives is
reported. The synthesis of asteltoxin, avenaciolide, and oxetanocin is also
reported. Asymmetric reactions on chiral glyoxylate is reported. The low
diastereoselectivity of the reaction with chiral ketones and aldehydes is
discussed. Finally, the high diastereoselectivity observed in the reaction with
2-furylmethanol derivatives is reported.
[Back to top] Chemistry of Bis-Spiroacetal Systems: Natural
Products, Synthesis and Stereochemistry
Margaret
A. Brimble and Daniel P. Furkert
In recent years a
number of compounds containing bis-spiroacetal systems have been isolated from
nature. Predominantly of dinoflagellate origin, they have stimulated much
synthetic interest due to their potent biological activity and synthetically
challenging structural features. Although the chemistry of bicyclic
spiroacetals is well understood, that of the tricyclic bis-spiroacetals has
been less fully explored. This review describes the strategies employed to
construct bis-spiroacetals with particular reference to stereochemical issues
associated with the quaternary spirocentres.
[Back to top] Carboxylate Binding by Guanidiniocarbonyl Pyrroles: From Self- Assembly
to Peptide Receptors
Carsten
Schmuck , Lars Geiger
The development of
novel building blocks which are capable to self-assemble and the design of
artificial receptors for a given substrate are two main goals in supramolecular
chemistry. Herein, we describe the synthesis and evaluation of a de novo
designed new binding motif for carboxylates in polar solution, the
guanidiniocarbonyl pyrroles. The thermodynamic properties of this new receptor
class were intensively studied both experimentally by NMR, X-ray and ESI MS,
and theoretically using molecular modelling. These studies led to a detailled
structural and thermodynamic understanding of the recognition event.
Futhermore, a comparative thermodynamic study allowed us to arrive at a
supramolecular structure-binding relationship (SSBR) for the complexation of
carboxylates by this receptor class.
Based on this novel recognition motif, new supramolecular structures can be designed. Self-complementary guanidiniocarbonyl pyrrole/carboxylate zwitterions form intramolecular loops, dimers or supramolecular oligomers depending on the molecular structure of the zwitterion and the experimental conditions. Guanidiniocarbonyl pyrrole cations can also be used as receptors for the side chain selective- and stereoselective complexation of amino acids in aqueous solvents. By incorporating such guanidiniocarbonyl pyrrole units into a combinatorial receptor library, one can also identify receptors for the effective complexation of biologically relevant oligopetides.