Hélène Bernard

A new route to cyclen, cyclam and homocyclen

Abstract Cyclen, cyclam and homocyclen have been synthesized from the corresponding butanedione-protected linear tetramines. The cyclization step is followed by a facile deprotection of the rigidifying moiety.

GENERAL ROUTE FOR THE SYNTHESIS OF MONO N-ALKYLATED DERIVATIVES OF TETRAAZAMACROCYCLES

Abstract The selective synthesis of mono N-substituted derivatives of tetraazamacrocycles can be achieved using a new boron triprotection easily removed after alkylation.

Condensation of glyoxal with triethylenetetraamine. Stereochemistry, cyclization and deprotection

Abstract A mixture of bis-aminal isomers was obtained from aqueous glyoxal-triethylenetetraamine condensation. The irreversible isomerization of the species was observed and a new synthesis of cyclen proposed.

Trivalent protecting groups for the synthesis of symmetrical and unsymmetrical bis-tetraazamacrocycles

Abstract Facile syntheses of bis-tetraazamacrocycles are reported starting from tripotection of tetraazamacrocycles. The triprotected macrocycle was mono N-alkylated and then this compound reacted with another macrocycle to give symmetrical or unsymmetrical bis-tetraazamacrocycles.

Condensation of Glyoxal with Triethylenetetraamine; Isomerization and Cyclization

The condensation of triethylenetetraamine with glyoxal leads to the formation of four stereoisomers A, B, C, D. A is the thermodynamic product and D the kinetic one. These four compounds exhibit equilibrium and isomerization phenomena which are the key-feature of this cyclen synthesis.

Modes of complexation of bis-aminals of linear tetraamines with Group 6 metal carbonyls

Abstract On reaction with Group 6 metal carbonyls M(CO)6, vic type bis-aminals L, issued from the condensation of an α-dicarbonyl compound on a linear tetraamine, give rise to mononuclear cis-M(CO)4L complexes.

Exploring new molecular architectures for anion recognition: synthesis and ATP binding properties of new cyclam-based ditopic polyammonium receptors.

Synthesis and characterization of three new polyamine receptors, composed of a cyclam unit (cyclam=1,4,8,11-tetraazacyclotetradecane) linked by a 2,6-dimethylpyridinyl spacer to the linear polyamines 1,4,8,11-tetraazaundecane (L1py), 1,4,7-triazaheptane (L2py), and to a quaternary ammonium group (L3py(+)), are reported. All receptors form highly charged polyammonium cations at neutral pH, suitable for anion recognition studies. ATP recognition was analyzed by using potentiometric, calorimetric, (1)H and (31)P NMR measurements in aqueous solution. All receptors form 1:1 adducts with ATP in aqueous solution, stabilized by charge-charge and hydrogen-bonding interactions between their ammonium groups and the anionic triphosphate chain of ATP. The binding ability of the three receptors for ATP increases in the order of L3py(+)<L2py<L1py. These adducts are stabilized by largely favourable entropic contributions, probably due to the large desolvation of the host and guest species upon complexation. The sequence observed for the binding affinity is explained in terms of the different ability of the three receptors to wrap around the phosphate chain of ATP.

Synthesis of a New Ditopic Ligand Possessing Linear and Cyclic Tetraaza Subunits

Abstract An easy‐to‐run route to a new ditopic ligand possessing linear and cyclic tetraaza subunits is described. In the first step, the reaction consists in the preparation of a triprotected cyclam bearing a 3‐bromopropyl pendant side chain. A subsequent reaction with a bisaminal protected linear tetraamine gives, after deprotection, the desired ditopic ligand.

Cyclohexanedione Bisaminals as Intermediates for Cyclen, Homocyclen, and Cyclam Synthesis

Abstract A new easy‐to‐run route to cyclen, homocyclen, and cyclam is proposed, based on the cyclization with dibromo‐ or ditosyloxy‐derivatives of bisaminal intermediates obtained by condensation of the appropriate linear tetraamine with cyclohexanedione. In the cyclization step, the use of cesium carbonate instead of potassium carbonate as proton trapper caused a remarkable increase of yields.

A [two-step/one week] synthesis of C-functionalized homocyclens and cyclams. Application to the preparation of conjugable BCAs without chelating properties alteration

A versatile and efficient bisaminal template approach for the synthesis of cyclam and [13]aneN4 (homocyclen) bifunctional chelating agents (BCAs) bearing a hydroxyethyl function as a C-appended group is presented. The synthesis is rapid (two steps/one week) and does not require fastidious protection–deprotection steps or chromatographic purification. Another reactional route and alternative work-up give access to their oxo-cyclam and oxo-homocyclen analogues. The procedure consists of the cyclization of the preorganized tetraamine 1,4,8,11-tetraazaundecane, in its cis-butanedione-bisaminal form, with an α,β-unsaturated lactone to provide the tetracyclic oxo-intermediate whose bisaminal bridge can be easily removed and/or its amide function reduced under mild conditions. Furthermore, the synthetic route was successfully applied to the synthesis of teta and trita BCAs analogues starting from the linear tetraamine 1,4,7,10-tetraazadecane. Additionally, the appended alcohol functions of various cyclam and homocyclen based ligands were converted into their ethylamine functions following a very convenient procedure. Finally, preliminary analytical and complexation studies highlight that the supplementary hydroxyethyl C-appended chain has only a low impact on the acid–base behaviour and copper(II) or zinc(II) coordination properties of the macrocycle.