Investigation of SmI2-mediated cyclisation of δ-iodo-α,β-unsaturated esters by deuterium 2D NMR in oriented solvents

Hélène Villar (1) , François Guibé (1) , Christie Aroulanda (1) , Philippe Lesot (1, 2)

1 ICMMO - Institut de Chimie Moléculaire et des Matériaux d'Orsay
2 CNRS - Centre National de la Recherche Scientifique

We have investigated the mechanism of the SmI2-mediated cyclisation of -iodo-,-unsaturated esters using protondecoupled deuterium 1D and 2D NMR in weakly ordered polypeptide liquid crystal solvents. Analysis of the spectroscopic results demonstrates that the cyclisation reaction takes place with concomitant and extensive racemisation at the -position and the reason for this racemisation is discussed. We also report an efficient 2D NMR strategy for distinguishing meso- from d- and l-diastereoisomers based on the introduction of a CD2 probe in the molecules to be studied. This approach allows determination of the diastereoisomeric and enantiomeric composition of a mixture

Mots clés: NMR; Deuterium; Enantiopurity; PBLG; SMI2

Domaines: Chimie analytique; Chimie organique

Hélène Villar, François Guibé, Christie Aroulanda, Philippe Lesot. Investigation of SmI2-mediated cyclisation of δ-iodo-α,β-unsaturated esters by deuterium 2D NMR in oriented solvents. Tetrahedron: Asymmetry, 2002, 13 (14), pp.1465-1475. ⟨10.1016/S0957-4166(02)00259-8⟩. ⟨hal-02310609⟩