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The alkylation of nucleophiles is among the most fundamental and well‐developed transformations in chemistry. However, to achieve selective alkylation of complex substrates remains a nontrivial task. We report herein a general and selective alkylation method without using strong acids, bases, or metals. In this method, the readily available phosphinites/phosphites, in combination with ethyl acrylate, function as effective alkylating agents. Various nucleophilic groups, including alcohols, phenols, carboxylic acids, imides, and thiols can be alkylated. This method can be applied in the late‐stage alkylation of natural products and pharmaceutical agents, achieving chemo‐ and site‐selective modification of complex substrates. Experimental studies indicate the relative reactivity of a nucleophile depends on its acidity and its steric environment. Mechanistic studies suggest the reaction pathway resembles that of the Arbuzov‐Michalis reaction. [ABSTRACT FROM AUTHOR]

Here we report a general approach to make unnatural amino acids from readily available cysteine derivatives. This method capitalizes on an intramolecular radical substitution process that generates alkyl radicals through C−S cleavage. The resulting alkyl radicals partook in diverse C−C bond forming events. These reactions proceed under mild, photocatalytic conditions at room temperature, and can be performed open to air. The utility of these transformations is further demonstrated in the straightforward synthesis of various unnatural amino acids and peptides that are difficult to access previously. [ABSTRACT FROM AUTHOR]

We here report glycosyl sulfoxides appended with an aryl iodide moiety as readily available, air and moisture stable precursors to glycosyl radicals. These glycosyl sulfoxides could be converted to glycosyl radicals by way of a rapid and efficient intramolecular radical substitution event. The use of this type of precursors enabled the synthesis of various complex C‐linked glycoconjugates under mild conditions. This reaction could be performed in aqueous media and is amenable to the synthesis of glycopeptidomimetics and carbohydrate‐DNA conjugates. [ABSTRACT FROM AUTHOR]

Direct and site-selective O-arylation of carbohydrates has been a challenge in synthesis. Herein we report a method based on copper-catalyzed O-arylation to address this challenge. Proper choice of the ancillary ligand on copper is critical for the efficiency and site selectivity of this transformation. This method features mild conditions, tolerates various functional groups, and demonstrates broad substrate scope. [ABSTRACT FROM AUTHOR]