Jesper Lau

Caesium tetrathiafulvalene-thiolates: key synthetic intermediates

Treatment of cyanoethylated tetrathiafulvalene-thiolates or cyanoethylated 1,3-dithiole-2-thione-4,5-dithiolate with one equiv. of caesium hydroxide hydrate selectively and in high yield produces the corresponding monocaesium salts, which can subsequently be alkylated.

Tetrathiafulvalenes in macrocyclic and supramolecular chemistry

We describe that use of a stepvise selective protection-deprotection of tetrathiafulvalene (TTF)-thiolates give rise to either two or three-dimensional macrobicyclic tetrathiafulvalenophanes in high yields by convergent syntheses. Configurationally selective self-assembly of cyclic or bicyclic tetrathiafulvalenes using the cyclic rc-acceptor cyclo-bis(paraquat-p-phenylene) yields [2]or [ 3lpseudocatenanes. Tetrathiafulvalenes Tetrathiafulvalenes (TTF’s) and related heterocycles have been of high interest for more than two decades, due to their unique rc-donor properties’. The unsubstituted TTF-molecule 1 is a planar non-aromatic 14-IT system. Oxidation takes place sequentially in two discrete reversible steps with formation of ; i: a radical cation 2 and i i : the 2 x IT dication 3: 2 3 1 TTF radical cation dication The redox potential for TTF is relatively low: E’1/2 = 0.35 and E21,2 = 0.71V (sv Ag/AgCl, MeCN/TBAHFP). Change of substituents (R’ or R2 ) at the TTF system 4, allows “fine tuning” of the redox properties. Among the large number of tetrathiafulvalenes which have been prepared, BEDT-TTF 5 is relative unique, it has given rise to more superconducting salts than any other TTF-derivative so far. 4 5 (BEDT-m) Conducting materials In order to develop new conducting charge transfer complexes and salts based on tetrathiafulvalenes it is necessary to control both the redox potential of the donor and the electron affinity of the acceptor simultaneously. However, it is still a fact that the control of the stoichiometry resulting in formation of partly ionized states between the donor and acceptor is serendipitous. Therefore control of the 2and 3dimensional molecular architecture of macrocyclic and oligo tetrathiafulvalenes is of great current interest, because it can be expected that their derived charge transfer salts may reveal new types of molecular interactions.

Macrocycles, pseudorotaxanes and catenanes containing a pyrrolo-tetrathiafulvalene unit: absorption spectra, luminescence properties and redox behavior

The photophysical properties of (i) three macrocycles (1–3) of different size, each one incorporating a bis(2,5-dimethylpyrrolo[3,4-d])tetrathiafulvalene (TTFP) and a 1,4-dimethoxybenzene (DMB) electron-donating unit, (ii) the six pseudorotaxanes obtained by threading 1–3 with the electron acceptors dimethyldiazapyrenium (DMDAP2+) and dibenzyldiazapyrenium (DBDAP2+) and (iii) the three catenanes obtained by interlocking 1–3 with the electron-accepting cyclophane cyclobis(paraquat-p-phenylene) (CBPQT4+) have been investigated. The monooxidized and dioxidized species obtained by oxidation with Fe(III) of the TTFP unit contained in the above compounds have also been studied. The redox-driven dethreading/rethreading process has been investigated in the case of the pseudorotaxane based on the macrocycle 2 and the DMDAP2+ dication. In the catenanes, oxidation of the TTFP unit causes strong spectral changes, but does not promote disruption of the interlocked structures.

Crystal structures and optical properties of cation radical salts of a tetrathiafulvalene trisannulated macrocycle

Cation radical salts of the bis(methylthio)tetrathiafulvalene (DMT-TTF) trisannulated macrocycles, [tris(DMT-TTF)]I3– (1) and [tris(DMT-TTF)]IBr2– (2), were prepared and the crystal structures and polarized reflectance spectra of the salts 1 and 2 were investigated. An isostructural character is observed for the two salts. The C3 symmetry of tris(DMT-TTF) bearing three equivalent DMT-TTF units (A, B, and C) within a molecule is broken through the formation of cation radical salts. Two DMT-TTF units (B and C) of three equivalent units form an intramolecular dimer structure through the face-to-face π–π overlap, whereas the plane of the A unit is orthogonal to the dimer plane and isolated from the other units. The intramolecular dimers are further dimerized through the intermolecular B–B′ interaction, resulting in a DMT-TTF tetramer unit (C–B–B′–C′) within the crystal. The intramolecular bond lengths and polarized reflectance spectra indicate the localization of a unit charge on the B unit rather than A or C. The charge separated A0–B+–C0 electronic structure is confirmed.

Stacked supramolecular structures involving hydrogen-bonded networks in highly functionalised tetrathiafulvalene derivatives

The solid-state structures of tetrathiafulvalene derivatives 1·2MeOH and 2 are established by single-crystal X-ray analysis, which reveals the coexistence of uniform π–π stacking and hydrogen-bonded O ⋯ H ⋯ O networks.

New Strategies in the Synthesis of 3′-Azido-2′,3′-dideoxy-nucleosides with Furanose Configuration

Abstract For the synthesis of 3′substituted 2′,3′dideoxynucleosides we have selected a convergent strategy in which a protected furanose derivative is coupled with a silylated base. This method seems to be the best for synthesizing a large number of nucleosides for the purpose of biological testing.

Syntiiesis of New 3′-Amino-2′,3′-Dideoxynucleosides in Five Steps Starting from Peracetylated Clycals

Abstract As amino sugars1 and aminonucleosides2 show remarkable anticancer and antiviral properties the synthetic and biological investigation in this field has become challenging.

Crystal structures of tetrathiafulvalene multiannulated macrocycles in open-shell electronic state

Abstract Crystal structures of dimethylthio-tetrathiafulvalene (DMT-TTF) multiannulated macrocycles, bis(DMT-TTF) and tris(DMT-TTF), were examined. The intramolecular dimerization was a common structural feature for these multi-TTF macrocycles in open-shell electronic state.

Tetrathiafulvalenes in Macrocyclic and Supramolecular Chemistry: Self Assembly with Tetrathiafulvalenes

We describe that use of stepvise selective protectiondeprotection of tetrathiafulvalene (TTF)-thiolates give rise to either two or three-dimensional macrobicyclic tetrathiafulvalenophanes in high yields by convergent syntheses. Configurationally selective selfassembly of cyclic tetrathiafulvalenes using the cyclic π-acceptor cyclo-bis(paraquat-p-phenylene) yields [2]- or [3]pseudocatenanes. A simple method for the preparation of donor-acceptor tetrathiafulvalenophanes is reported.

2,3-Dideoxy-3-Phthalimidopentoses in the Synthesis of 3'-Amino-2',3'-Dideoxynucleosides

Abstract 3′-Amino-3′deoxythymidine is a very effective drug in vivo against L 1210 leukemia. It mives 1441 increase in lifespan with very little drug-induced toricitylil. Therefore, it was attractive to synthesize a large series of cuialogues, but unfortunately, such compounds are only achievable through a 1inear synthesis via the corresponding nucleoside which typically is transformed into the 3′-azido derivative and finally reduced.