‘One-pot’ four-step synthesis of cerpegin

Cerpegin (1) was synthesized through a ‘one-pot’ reaction in 71% overall yield. Lithiation of commercially available 2-methoxynicotinic acid (2) as its lithium salt using LTMP, followed by addition of acetone at low temperature and a specific acidic treatment of the intermediate 3 thus obtained, gave the 1,1-dimethyl-3,4-dioxo-1,3,4,5-tetrahydrofuro[3,4-c]pyridine (4). The latter was finally selectively alkylated using methyl iodide and caesium carbonate to afford cerpegin (1).     

Studies towards the total synthesis of Sch 56036; isoquinolinone synthesis and the synthesis of phenanthrenes

The isoquinolinone hemisphere of Sch 56036 has been prepared using a modified Pomeranz-Fritsch reaction and the synthesis of the phenanthrene core has been modelled via a Suzuki coupling and subsequent ring closing metathesis.     

A short synthesis of de-‘prenyl’-ardeemin

A four-step synthesis of the ardeemin framework by starting from N-2-aminobenzoyl-α-amino esters is described. In the last step, the acid promoted cyclization of the 1,4-anti-4-alkyl-1-(3-indolylmethyl)-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones occurs irreversible and stereocontrolled.     

Diversity‐oriented synthesis

Diversity‐oriented synthesis (DOS), which describes the synthesis of structurally diverse collections of small molecules, was developed, in part, to address combinatorial chemistry's shortfalls. In this paper, we hope to give an indication of what can be achieved using the DOS approach to library generation. We describe some of the most successful strategies utilized in DOS, with special focus on our own area of interest; DOS from simple, pluripotent starting materials. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 129–142; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20144     

‘Click’ synthesis of triazole-based spirostan saponin analogs

Novel analogs of spirostan saponins in which the glycosidic bond has been replaced by a triazole linkage are described. For this, a direct oligosaccharide-steroid conjugation approach based on the Cu^I-catalyzed azide-alkyne 1,3-dipolar cycloaddition was implemented, leading to diverse combinations of saponin analogs with variations in the trisaccharide moiety, the artificial linkage, and the steroid-skeleton functionalization. This ‘click’ process proved great efficiency for the ligation of two bulky building blocks (e.g., chacotriose derivatives and spirostanes bearing axial azides), which enabled the rapid creation of a small library of triazole-based analogs for cytotoxicity evaluation. A molecular modeling study was performed to understand the conformational and electronic differences between a natural saponin and its triazole-based analogs.     

Photochemical synthesis of gold–polyethylenglycol core–shell nanoparticles

A new, fast and convenient method for the preparation of gold–polyethylenglycol core–shell nanoparticles in water was described. The method pertains to the concomitant redox and polymerization reactions of the acrylic formulation induced by photochemically generated radicals from the photoinitiator, 2-hydroxy-2-methyl-1-phenyl-1-propanone. The nanoparticles were characterized by using Dynamic Light Scattering (DLS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). Homogenous core–shell structured nanoparticles obtained this way are expected to find important applications in bio-medical fields.     

Microwave-assisted synthesis of 4,4′-diaminotriphenylmethanes

A fast, efficient and versatile route of synthesis of 4,4′-diaminotriphenylmethanes under microwave irradiation, suitable for parallel library syntheses were developed.     

Polyhydroxylated indolizidine alkaloids—synthesis of dideoxycastanospermine

The key transformation developed in this work is the anti-Kishi selective dihydroxylation, which proceeds by way of intramolecular participation of the nitrogen protecting group to furnish the desired stereochemistry required for castanospermine like structures. In this paper, we completed a first synthesis of a novel dideoxycastanospermine 6.     

Solvent‐free synthesis of rotaxanes

Rotaxane‐type (macro)molecules are important materials in various fields of research, with many approaches for their synthesis having been developed over the past 30 years or so. When prepared in solution, the efficiency of interlocking pseudorotaxane complexes into the corresponding rotaxanes relies, to a great extent, on the affinity between the host and guest components; these interactions are not always sufficiently strong to overcome the deleterious effects of high reaction temperatures, competitive solvents, and low concentrations. Upon evaporating the solvent, however, the concentrations of the host and guest species increase significantly and, ultimately, their corresponding pseudorotaxanes can be generated with high efficiency in the solvent‐free residue. Furthermore, in the absence of the solvent, the influence of any disrupting byproducts (generated during the interlocking process) on the complexation equilibrium can also be largely reduced. Therefore, high synthetic efficiency and low consumption of solvents and energy can be expected when synthesizing rotaxanes under solvent‐free conditions. This mini‐review covers the main publications dealing with the solvent‐free syntheses of rotaxanes – those in which the interlocking step involves no solvent (or only a trace of it).     

CyanobenzeneTTF-type donors; synthesis and characterization

Two cyanobenzeneTTF-type electron donors, which are also dithiolene ligand precursors, cyanobenzenedicyanoethylthiotetrathiafulvalene, (cbdc-TTF) and dicyanobenzenedicyanoethylthiotetrathiafulvalene, (dcbdc-TTF), were obtained through cross-coupling reactions with triethyl phosphite between 4,5-bis(2-cyanoethylthio)-1,3-dithiole-2-one and 4,cyanobenzene-1,3-dithiole-2-thione or dicyanobenzene-1,3-dithiole-2-thione, respectively. These reactions also yield 2,3,6,7-tetrakis(2-cyanoethylthio)-TTF and the corresponding symmetric cyanobenzene TTF derivatives dicyanodibenzenetetrathiafulvalene (dcdb-TTF) and tetracyanodibenzotetrathiafulvalene (TCN-DBTTF) resulting from the self-coupling reactions of the ketone and the thiones. Compound dcdb-TTF was also synthesized by homo-coupling reaction of the cyanobenzene-1,3-dithiole-2-ketone with triethyl phosphite. These compounds were characterized namely by single crystal X-ray diffraction and cyclic voltammetry.