Juliette Fitremann

Transesterification of Sucrose in Organic Medium: Study of Acyl Group Migrations

The tendency of the acyl groups located on the glucose part of sucrose fatty acid esters to undergo intramolecular migrations in organic medium and the regioselectivity of some transesterifications of sucrose were investigated by HPLC, in situ NMR spectroscopy and preparative methods. Extensive acylation on secondary positions of the glucose moiety followed by migrations is general for base catalysed transesterification. The stability of 3‐ and 6‐O‐acyl derivatives, two isomers being thermodynamically favored compared to others, was studied in a series of conditions. It is shown that the presence of water catalyzes the migration of the ester at OH‐3 towards OH‐6 in organic basic medium, whereas the ester at OH‐6 appears more stable under either acidic or basic conditions. †This paper is dedicated to Professor Gérard Descotes on the occasion of his 70th birthday, in acknowledgement of his accomplishments in the field of carbohydrate chemistry, and of his continuing efforts for developing the use of renewable sugars for chemistry.

2,5-disubstituted pyrrolidines from D-mannitol-derived bis-aziridines

Abstract Concise syntheses of 3,4-dihydroxy-2,5-disubstituted pyrrolidines have been achieved starting from D-mannitol-derived flexible L-Ido bis-aziridines. Nucleophilic ring opening of the N-Boc and the N-Cbz activated bis-aziridines by phenylthiolate and azide ions has been studied ; the reaction can be oriented either toward bis-opening (derivative A) or heterocyclization. Heterocyclization leads to a 1:9 mixture of the enantiopure polysubstituted piperidines B and pyrrolidines C.

New C2 symmetric bis-aziridines efficient synthesis of (2S,5S)-1,6-Di(p-toluenesulfonyloxy)-2,5-hexanediol, and (2S,3E,5S)-1,6-Di(p-toluenesulfonyloxy)-2,5-hexenediol

The regioselective tosylation and functionalization of (S,S)-1,2,5,6-hexanetetrol is reported. The reductive aminocyclization of conformationally flexible diazidodiols by PPh3 leads to C2 symmetric bis-aziridines and to substituted furans.

Calcium Phosphate Bone Cements Including Sugar Surfactants: Part One—Porosity, Setting Times and Compressive Strength

Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides, to calcium phosphate cement designed for bone reconstruction is described. Thanks to their surface activity and through their adsorption at the surface of the calcium phosphate particles, they both induced a strong increase in the porosity (quantified by Image Analysis) and brought a very good workability. Other properties typically studied for these cements are reported, including setting times, compressive strength, cohesion in water, and effect of sterilization on these properties. The whole study brought good insight in the interest of adding these mild surfactants to improve several properties of the calcium phosphate cement, without impairing their function.

Calcium Phosphate Bone Cements Including Sugar Surfactants: Part Two—Injectability, Adhesive Properties and Biocompatibility

Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides to a calcium phosphate cement, designed for bone reconstruction, is described. Thanks to their adsorption at the surface of the calcium phosphate particles, the sugar surfactants allowed a full injectability and brought a very good workability. Injectability was measured by monitoring force-distance curves. With some of the selected sugar surfactants adhesive properties of the cement pastes were also observed, which were measured by tack tests. Finally, some properties related to biological applications are described, including gentamicine release and osteoblast viability experiments. The whole study demonstrates that addition of these mild surfactants improved several properties of the calcium phosphate cement, without impairing function.