A protocol for stereoselective C-radical addition to a chiral glyoxylate-derived N-sulfinyl imine was developed through visible light-promoted photoredox catalysis, providing a convenient method for the synthesis of unnatural α-amino acids. The developed protocol allows the use of ubiquitous carboxylic acids as radical precursors without prior derivatization. The protocol utilizes near-stoichiometric amounts of the imine and the acid radical precursor in combination with a catalytic amount of an organic acridinium-based photocatalyst. Alternative mechanisms for the developed transformation are discussed and corroborated by experimental and computational studies.

A novel glycosyl donor with a triisopropylsilyl (TIPS) nonparticipating group at O-2 is introduced for use in 1,2-cis-galactosylation. Coupling the 2-O-TIPS-substituted thiogalactoside donor with a series of mono- and disaccharide glycosyl acceptors was found to lead exclusively to α-linked oligosaccharides. The observed exceptionally high α-selectivity was interpreted in terms of conformational changes in the glycosyl cation induced by the bulky 2-O-TIPS group.

The outcome of the nucleophilic opening of 3-O-benzoyl-β-d-arabinofuranose 1,2,5-orthobenzoate with 4-(ω-chloroalkoxy)phenols (SnCl₄, CH₂Cl₂, –25 °C) unusually strongly depends on the length of the methylene chain of the nucleophile. The presence of one extra methylene group in the molecule of 4-(3-chloropropoxy)phenol [as compared to 4-(2-chloroetoxy)phenol] results in four-fold reduction in the reaction time and five-fold increase in the yield of a selectively protected monosaccharide glycoside with a hydroxy group at C-5, which is a valuable building block for the synthesis of oligoarabinofuranosides related to mycobacterial arabinans. Possible reasons and consequences of this finding are discussed.