Stereoselective synthesis of novel C-azanucleoside analogues by microwave-assisted nucleophilic addition of sugar-derived cyclic nitrones

Synthesis of bis-Phosphate Iminoaltritol Enantiomers and Structural Characterization with Adenine Phosphoribosyltransferase

Phosphoribosyl transferases (PRTs) are essential in nucleotide synthesis and salvage, amino acid, and vitamin synthesis. Transition state analysis of several PRTs has demonstrated ribocation-like transition states with a partial positive charge residing on the pentose ring. Core chemistry for synthesis of transition state analogues related to the 5-phospho-α-d-ribosyl 1-pyrophosphate (PRPP) reactant of these enzymes could be developed by stereospecific placement of bis-phosphate groups on an iminoaltritol ring. Cationic character is provided by the imino group and the bis-phosphates anchor both the 1- and 5-phosphate binding sites. We provide a facile synthetic path to these molecules. Cyclic-nitrone redox methodology was applied to the stereocontrolled synthesis of three stereoisomers of a selectively monoprotected diol relevant to the synthesis of transition-state analogue inhibitors. These polyhydroxylated pyrrolidine natural product analogues were bis-phosphorylated to generate analogues of the ribocationic form of 5-phosphoribosyl 1-phosphate. A safe, high yielding synthesis of the key intermediate represents a new route to these transition state mimics. An enantiomeric pair of iminoaltritol bis-phosphates (L-DIAB and D-DIAB) was prepared and shown to display inhibition of Plasmodium falciparum orotate phosphoribosyltransferase and Saccharomyces cerevisiae adenine phosphoribosyltransferase (ScAPRT). Crystallographic inhibitor binding analysis of L- and D-DIAB bound to the catalytic sites of ScAPRT demonstrates accommodation of both enantiomers by altered ring geometry and bis-phosphate catalytic site contacts.

Pyrroles versus cyclic nitrones: catalyst-controlled divergent cyclization of N-(2-perfluoroalkyl-3-alkynyl) hydroxylamines

Divergent cyclizations ofN-(2-(perfluoroalkyl)-3-alkynyl) hydroxylamines1have been realized by subtle choice of the catalyst under mild conditions, leading to two distinct types of synthetic valuable compounds, cyclic nitrones2and pyrroles3, in moderate to excellent yields.

An efficient synthesis of aldohexose-derived piperidine nitrones: precursors of piperidine iminosugars

d-Glucopyranose-derived and l-idopyranose-derived piperidine nitrones were synthesized in good overall yields through six-step reaction sequence starting from readily available 2,3,4,6-tetra-O-benzyl-d-glucopyranose. The method is efficient and could be general for the synthesis of aldohexose-derived piperidine nitrones which are precursors of piperidine iminosugars.

(2R,3S,4R)-3,4-Isopropylidenedioxy-2-(phenylsulfonylmethyl)pyrrolidin-1-ol

The title compound, C₁₄H₁₉NO₅S, was prepared by nucleophilic addition of the lithium derivative of methyl­phenyl­sulfone to (3S,4R)-3,4-isopropyl­idene­dioxy­pyrroline 1-oxide. There are four mol­ecules in the asymmetric unit. The crystal structure determination confirms the configuration of the chiral centres as 2R,3S,4R. In the crystal, pairs of O—H⋯N hydrogen bonds link the mol­ecules into dimers.