Luigi Longobardo

Synthesis of Enantiopure N-and C-Protected homo-β-Amino Acids by Direct Homologation of α-Amino Acids ¶

Abstract Enantiopure N-and/or C-protected homo-β-amino acids are prepared readily and in good yields from N-protected α-amino acids with the same side chain, via reduction of the carboxyl function and conversion of the resulting N-protected β-amino alcohol into the corresponding β-amino iodide and then β-amino cyanide. The key step of this strategy is represented by the synthesis of the enantiopure N-protected β-amino iodides 2 and 3 that are smoothly obtained from the parent amino alcohols 1 by polymer bound triarylphosphine-I2 complex in anhydrous dichloromethane.

Chiral N-protected β-iodoamines from α-aminoacids: a general synthesis

N-Protected d- or l-β-iodoamines (as 2), which are useful intermediates for the preparation of chiral β-aminoacids, are obtained smoothly from β-aminols (as I) in two steps and high yields.

Asymmetric induction in the coupling of 5,6-dihydro-1,4-dithiins with chiral aldehydes. A new synthetic approach to polyhydroxylated compounds☆

Abstract A new strategy is designed to synthesize polyhydroxyl compounds (and/or carbohydrates) by coupling of 5,6-dihydro-1,4-dithiins - carrying a vinylic hydrogen atom - with chiral aldehydes and, in sequence, stereoselective removal of the dithiodimethylene dithiin bridge and stereospecific hydroxylation of the resulting polyhydroxyl alkenes. In this paper the study of both coupling and desulfurization steps is reported by the use of 2-phenyl-5,6-dihydro-1,4-dithiin (5) as a model compound in the reactions with three chiral aldehydes, 3a,b and 4.

Quantification of gliadin levels to the picogram level by flow cytometry.

Celiac disease is a widely prevalent enteropathy caused by intolerance to gliadin, one of the gluten proteins. We developed two methods for the analysis of gliadin levels. Both methods use flow cytometry and rat antibodies against a 16‐residue peptide of gliadin. The peptide is common to the α‐, β‐, γ‐, and ω‐gliadins.

Novel thiol- and thioether-containing amino acids: cystathionine and homocysteine families

Natural l-homocysteine and l,l-cystathionine, along with a series of unnatural analogues, have been prepared from l-aspartic and l-glutamic acid. Manipulation of the protected derivatives provided ω-iodoamino acids, which were used in thioalkylation reactions of sulfur nucleophiles, such as the ester of l-cysteine and potassium thioacetate.

Novel sulfur and selenium containing bis-α-amino acids from 4-hydroxyproline

The synthesis of new substituted prolines carrying at C-4 a second α-amino acid residue is reported. The amino acid, l-cysteine or l-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared with different stereochemistry at C-4, in few and clean high-yielding steps, with suitable protections for solid phase applications. The introduction of both sulfur and selenium atoms at C-4 of the proline ring seems to enhance significantly the cis geometry at the prolyl amide bond.