Robert Méric

Binding of acetylcholine and other quaternary ammonium cations by sulfonated calixarenes. Crystal structure of a [choline-tetrasulfonated calix[4]arene] complex

Abstract The water-soluble tetra- and hexasulfonated calix[4] and calix[6]arenes bind very strongly the neurotransmitter acetylcholine and other quaternary ammonium cations with association constants Ks up to 4×105 M−1 for NEt4 +. The high affinities for choline and acetylcholine (Ks=5×104 to 8×104 M−1) are comparable to those of the biological recognition sites. The crystal structure of the [choline-tetrasulfonated calix[4]arene] complex was determined. Two complexes A and B were observed in the asymmetric unit. In each one, the choline inserts its N-terminal inside the cavity of the receptor. The calix[4]arene adopts a single cone conformation but the choline substrate is in an extended conformation in complex A and adopts two other folded conformations in complex B (75 % –25 %). The very high association constants and the crystal structure provide important information about the nature of the binding in this biologically most relevant complex.

L'eldanolide, phéromone des glandes alaires de la pyrale de la canne à sucre, eldana saccharina (wlk.): structure et synthèse de ses deux énantiomères

Abstract The isolation and structure determination of eldanolide, the wing gland pheromone of the male African Sugar Cane Borer, Eldana saccharina (Wlk.) is described. The absolute configuration was determined as (3S, 4R) by comparison of the CD spectra of the natural pheromone with both synthetic enantiomers.

Absolute configuration of eldanolide, the wing gland pheromone of the male African sugar cane borer, Eldana saccharina (Wlk.) syntheses of its (+) and (−) enantiomers.

Abstract Eldanolide 1 , a novel terpenoid lactone pheromone, was shown to have (3S,4R) configuration by synthesis of both enantiomers and comparison of their CD with the natural pheromone.

Polyaza-macrocycles of cyclophane type: synthesis, structure of a chloroform inclusion complex and anion binding

Abstract Polyazamacrocycles (1)–(7) have been obtained via efficient (amine + aldehyde) polycondensation processes. The tetraimine (1) forms a chloroform inclusion complex whose crystal structure has been determined; the protonated tetraamine (5) binds dicarboxylate substrates.

Molecular recognition of anionic substrates. Binding of carboxylates by a macrobicyclic coreceptor and crystal structure of its supramolecular cryptate with the terephthalate dianion

The macrobicyclic polyammonium receptor molecule 1–6H+ binds dicarboxylate substrates with linear recognition and forms with terephthalate a very stable dianion cryptate the crystal structure of which has been determined.

Preparation des methyl-4 heptanols-3 erythro et threo optiquement purs.

Resume Optically pure enantiomers of threo and erythro 4-methylheptan-3 ols are synthesized from optically active butenolides 2 and 3 obtained via an asymmetric synthesis of propargylic carbinols.

Efficient complexation of quaternary ammonium compounds by a new water-soluble macrobicyclic receptor molecule

The hexacarboxylic macrobicycle 1 is a readily accessible water-soluble receptor molecule which binds strongly cuaternary ammonium cations.

Medium effects in action, visualized by the crystal structures of open and closed forms of a molecular receptor

The water-soluble macrobicyclic cyclophane molecule 16– has been crystallized in two very different shapes that display the operation of medium, especially hydrophobic effects: an inflated cage structure building up cylinders disposed in an hexagonal array; a flattened structure stacked in molecular layers separated by aqueous layers in a lamellar arrangement.