J. M. Llera

Simple and efficient conversion of N,N-dimethylhydrazones and aldehydes to nitriles.

Aldehyde N,N-dimethylhydrazones undergo facile oxidative cleavage to nitriles on reaction with magnesium monoperoxyphtalate hexahydrate (MMPP)

Enantioselective Diels-Alder reactions catalyzed by chiral magnesium lewis acids prepared from hydroxysulfoxides

Abstract Enantioselective Diels-Alder reactions were conducted successfully using chiral magnesium complexes prepared from magnesium iodide and chiral hydroxysulfoxides derived from ( R )- and ( S )-methyl 1-naphthyl sulfoxide. Convenient methods for the preparation of these chiral sulfoxides have also been developed. Hydroxysulfoxide 6 (and its enantiomer 10 ) showed the highest enantioselectivity.

A convenient synthesis of (E)-γ-hydroxy- and (E)-γ-keto-α,β-unsaturated sulfoxides

Abstract ( E )- γ -Hydroxy and ( E )- γ -keto- α , β -unsaturated sulfoxides have been easily prepared in good chemical yield from simple aldehydes 2 and chiral bis-sulfoxide 4 using a SPAC-type reaction. The onepot procedure is based on a Knoevenagel condensation, subsequent prototropic shift and [2,3] sigmatropic sulfoxide-sulfenate rearrangement.

Asymmetric synthesis of functionalized nitrocompounds through Michael addition of formaldehyde SAMP hydrazone to nitroolefins

Abstract Chiral β-nitrohydrazones 7 can be easily prepared in good yields and diastereoselectivities by non catalyzed Michael addition of formaldehyde SAMP hydrazone 6 to simple nitroolefins.

A short route to homochiral D-and L-hexose precursors from (R)-methyl-p-tolylsulfoxide

Abstract Homochiral D - and L -hexose precursors have been prepared in good overall yield from ( R )-methyl- p -tolylsulfoxide as the sole asymmetric inductor. The process involves sequential condensation of the sulfoxide with ethyl 2-furancarboxylate, stereoselective sulfoxide-monitored carbonyl reduction, Pummerer rearrangement of the sulfinyl group, reduction of the resulting aldehydes and ring-oxidation of the corresponding furfuryl alcohols.

Studies on conformation and configuration of β-hydroxysulphoxides

Abstract In this paper, the conformational and configurational analyses of cyclic and acyclic β-oxygenated sulphoxides are reviewed. In addition, the conformational behaviour of pairs of diastereomeric 2-(alkylsulphinyl)-1-arylethanols, Ar-CH(OH)-CH 2 -SOR (R = Me, Bu τ ; Ar = phenyl, furyl, thienyl) and their O -methyl derivatives has been studied. From the 1 H-NMR and IR data obtained, together with the published results for other analogous β-oxygenated sulphoxides, the role played by stereoelectronic interactions, hydrogen bonding and steric factors on conformational equilibria has been established. Finally, the relative configurations of these pairs of diastereomers have been correlated with 13 C-NMR data. We thus establish an easy and efficient method for the configurational assignment of β-hydroxysulphoxides, based on 13 C-NMR spectroscopy.

The fixing role of the tert-butyl group in the conformational properties of acyclic sulphur compounds. Synthesis and conformational analysis of 2-tert-butylthioderivatives of 1-phenylethanol and their ο-methyl analogs

Abstract The synthesis and conformational analysis of the title compounds are reported. The conformational equilibria have been established from 1 H-NMR data and the role of hydrogen bonding in the hydroxylated compounds has been studied by high dilution IR spectroscopy. In all of these derivatives, the bulky Bu t group blocks rotation around the C-S bond. The results for these compounds are compared with those reported for their analogous 2-methylthioderivatives. For sulphones and RR/SS sulphoxides, the possible dihedral angle deformations have also been evaluated.

SYNTHESIS AND CONFORMATIONAL ANALYSIS OF 2-METHYLTHIO DERIVATIVES OF 1-(2˭THIENYL)ETHANOL AND THEIR OMETHYL DERIVATIVES

Abstract The synthesis and conformational analysis of the title compounds are reported. The conformational properties of the 2-thienyl derivatives, deduced from 1H-nmr and ir data, are compared with those for 2-furyl analogs and the results have been interpreted taking into account the stronger (OH…Ring) intramolecular association in the 2-furyl derivatives.