Felipe Alcudia

C2-Symmetric bis-sulfoxides as chiral ligands in metal catalysed asymmetric diels-alder reactions.

(S,S)-bis-p-Tolylsulfinylmethane. 1, and (S,S)-2,2-bis-(p-Tolylsulfinyl)propane, 2, were converted into their Fe(III) complexes I and II, respectively. These complexes were shown to be good chiral catalysts of the Diels-Alder reaction betwen 3-acryloyl-1,3-oxazolidin-2-one, 4,

Asymmetric synthesis of optically pure tert-butyl sulfoxides using the “DAG methodology”

Abstract Diacetone- D -glucose (DAG) reacts with t -BuSOCl in the presence of NEt 3 and Py to give (−)-( S )- and (+)-( R )- tert -butanesulfinate respectively, in high diastereomeric excess. These sulfinates were transformed into various enantiomerically pure tert -butyl sulfoxides by reaction with different Grignard reagents. Additionally, the reaction of tert-butylmagnesium chloride with (+)-( R )- and (−)-( S )-methanesulfinates of DAG has been found to occur with complete inversion of configuration and not with retention as previously reported.

An efficient synthesis of both enantiomers of chiral non racemic methylsulfoxides from DAG

Abstract Diacetone-D-Glucose is stereoselectively converted to its (S)- or (R)-methanesulfinates 1 and 2 in 90 and 87% yield by treatment with methylsulfinyl chloride in the presence of diisopropylethylamine or pyridine, respectively. After purification, sulfinates 1 and 2 were transformed into both epimers of enantiomerically pure methylsulfoxides by reaction with Grignard reagents.

Alkylating agents from sugars. Alkyl hexopyranoside derivatives as carrier systems for chlorambucil

Chlorambucil derivatives involving alkyl 2-aminodeoxy sugars have been synthesized in good yield by coupling the chlorambucil moiety to positions C-2 or C-3 of the sugar, directly or via a spacer. The starting material was easily available from 2-acetamido-2-deoxy-D-glucose. The final compounds were tested for cytotoxicity, and some of those that presented the best results were studied for inhibition of cell proliferation.

Alkylating agents from sugars. Cyclophosphamides derived from 2-amino-2-deoxy-d-allose

Abstract Cyclophosphamides derived from alkyl 2-amino-4,6- O -benzylidene-2-deoxy- β - d -allopyranosides have been synthesized with good yield by treatment of the corresponding 2-amino-2-deoxy- d -allose derivatives with bis(2-chloroethyl)phosphoramide dichloride. The ring-forming reaction took place with very high diastereoselectivity. Subsequent hydrogenolysis gave excellent yields of cyclophosphamides derived from alkyl 2-amino-2-deoxy- β - d -allopyranosides, with hydrophilicity greater than that of the precursors. The starting material was easily available from 2-acetamido-2-deoxy- d -glucose.

Stereochemistry of organic sulphur compounds. part 13. Configurational assignment of diastereoisomers of 2-methylsulphinyl-1,2-diphenylethanol and of their O-methyl and O-acetyl derivatives

Abstract The synthesis, isolation and conformational analysis of the diastereomeric 2-methylsulphinyl-1,2-diphenylethanol and of its O -methyl and O -acetyl derivatives are reported. Chemical correlations and the study of the influence of solvent polarity changes on the coupling constants have permitted the configurational assignment. Lanthanide shift reagents have been used also. to this effect. The role of hydrogen bonding in the hydroxysulphoxides has been evaluated in diluted solutions by IR and NMR spectroscopy. A donor-acceptor interaction between oxygen and sulphur has been invoked to explain the differences in conformational behaviour between epimeric sulphoxides at sulphur atom.

A generalization of the base effect on the diastereoselective synthesis of sulfinic and phosphinic esters

Abstract Various chiral secondary alcohols have been used to study the dependence of the stereochemical outcome of sulfinate and phosphinate ester synthesis on the nature of the base used to catalyse the reaction. From this study it has been shown that the achiral stereodirecting base effect determined in the DAG methodology is a general behaviour in the asymmetric synthesis of sulfinate and phosphinate esters.

Unprecedented base effect on the synthesis of chiral phosphinate esters: A new route to P-chiral phosphine oxides of high enantiomeric purity

Abstract The stereochemical outcome of the reaction of chiral secondary alcohols with a phosphinyl chloride was found to be highly dependent on the achiral base used. Thus, the reaction of the readily available sugar derived carbinols, 1 and 2 , with methylphenylphosphinyl chloride in the presence of triethylamine yields stereoselectively the corresponding S np-phosphinates 3 S p and 5 S p in 94 and 92% diastereomeric excess (de). Simply changing the base from triethylamine to pyridine affords R p-phosphinates 4 R p and 6 R p epimers to 3 S p and 5 S p at the phosphinyl phosphorus in 50 and 40% de respectively. These phosphinate esters were found to be good P-chiral transferring intermediates, they react with Grignard reagents under very mild conditions to give the corresponding phosphine oxides. Both enantiomers S p- and R p- o -anisylmethylphenylphosphine oxide (PAMPO) as well S p- and R p- methylphenylpropyl phosphine oxide were obained enantiomerically pure in high yields

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.

Stereochemistry of organic sulphur compounds. part 14 . synthesis and conformation analysis of 1-thioderivatives of 3,3-dimethyl-2-butanol and its acetates

Abstract The synthesis and conformational analysis of some thioderivatives But-CHX-CH2Y (X = OH and OAc: Y = SH, SMe, SO2Me and SMe2) are reported. The conformational equilibra have been established from IH-NMR data and high dilution ir studies. All the compounds exhibited almost monoconformational behaviour around the C(1)-C(2) bond, due to strong steric factors. The observed vicinal coupling constants were used to check the different parameterizations of Altonas equation for our compounds with sulphur in distinct oxidation states. The possible dihedral angle deformations were also evaluated.