Emanuele Attolino

Biselector enantioselective stationary phases for HPLC: dependence of the chiral discrimination properties on stereochemistry and chemical nature of each unit of the chiral auxiliary

Abstract Optically active 1-(1-naphthyl)ethylamine, N -3,5-dinitrobenzoylphenylglycine and N -3,5-dinitrobenzoylleucine were used as chiral building blocks to prepare three new enantiomerically pure bifunctional chiral auxiliaries for enantioselective HPLC, belonging to a family of biselector systems, the first example of which ( CSP1 ) has been described previously. These compounds were covalently linked to silica gel to produce three chiral stationary phases ( CSPs 2 – 4 ), whose enantiodiscriminating capability towards the HPLC resolution of selected racemic compounds was assessed. The obtained results allowed us to establish the influence of the stereochemistry and/or the chemical structure of each chiral moiety of the biselector system on their enantiorecognition properties.

Improved Preparation of β‐d‐ManNAc‐(1→4)‐d‐Glc and β‐d‐TalNAc‐(1→4)‐d‐Glc Disaccharides and Evaluation of Their Activating Properties on the Natural Killer Cells NKR‐P1 and CD69 Receptors

This article has been retracted.

An efficient and highly regioselective synthesis of 4-deoxy- and 2-acetamido-2,4-dideoxy-β-d-threo-hex-3-enopyranosides

Abstract The preparation of the previously undescribed class of 4-deoxy- and 2,4-dideoxy-2-acetamido-β- d - threo -hex-3-enopyranosides was accomplished with a very high yield and a complete regioselectivity by means of a simultaneous activation–elimination process of the OH-4 group of β- d -talopyranosides ( 5a , b ) and 2-acetamido-2-deoxy-β- d -talopyranosides ( 5c , d ) with NaH/ N , N ′-sulfuryldiimidazole. The same reaction of analogous β- d -galactopyranosides ( 5e , f ) is not regioselective, leading to mixtures of 3- and 4-hexeno derivatives. This difference is evidently determined by the orientation of the C-2 substituent, which, in the talo series, is anti diaxially disposed to the H-3 eliminating group.

A new stereocontrolled access to β-d-mannopyranosides and 2-acetamido-2-deoxy-β-d-mannopyranosides starting from β-d-galactopyranosides

Abstract A new stereocontrolled synthesis of β- d -mannopyranosides was defined relying on a high yielding sequence based on the following three key steps: (a) a stereospecific inversion at C-2 of β- d -galactopyranosides by an oxidation–reduction procedure; (b) a regiocontrolled formation of 4-deoxy-β- d -threo-hex-3-enopyranosides; (c) a regio- and stereocontrolled hydroboration–oxidation of the above enol ethers. The flexibility of this new method was demonstrated by its extension to the synthesis of 2-acetamido-2-deoxy-β- d -mannopyranosides and of an orthogonally protected β- d -mannopyranoside scaffold and, finally, by the transformation of lactose into the two biologically relevant disaccharides with primary structure β- d -Manp-(1→4)- d -Glc and β- d -ManNAcp-(1→4)- d -Glc.