Selective C–N bond oxidation: demethylation of N-methyl group in N-arylmethyl-N-methyl-α-amino esters utilizing N-iodosuccinimide (NIS)

Construction of Acyclic All-Carbon Quaternary Stereocenter Based on Asymmetric Michael Addition of Chiral Amine

Acyclic asymmetric quaternary stereocenters, which are composed of four carbon-carbon bonds, were finely constructed by utilizing a face-selective alkylation of enolate intermediates derived from an asymmetric Michael addition reaction of a chiral lithium amide with trisubstituted (E)-α,β-unsaturated esters. The present face-selective alkylation was able to employ diverse alkyl halides as an electrophile to afford various Michael adducts having an all-carbon quaternary stereocenter. With regard to the deprotection of the chiral auxiliary, N-iodosuccinimide used in our previous study did not work in the present cases; however, we found that pyridine iodine monochloride in the presence of H₂O was effective to remove the bornyl group and the benzyl group on the amino group to provide the β-amino ester derivative.

Negamycin analogue with readthrough-promoting activity as a potential drug candidate for duchenne muscular dystrophy

A series of (+)-negamycin 1 analogues were synthesized, and their readthrough-promoting activity was evaluated for nonsense mutations in Duchenne muscular dystrophy (DMD). A structure-activity relationship study indicated that 11b was the most potent drug candidate. Immunohistochemical analyses suggested that treatment with 11b restored dystrophin expression in mdx mice, a DMD mouse model. Furthermore, 11b decreased serum creatine kinase (CK) levels, an indicator of muscle fiber destruction. Most importantly, 11b demonstrated lower toxicity than 1, and thus, it could be a useful candidate for long-term treatment of DMD.

Umpolung reactivity in amide and peptide synthesis

The amide bond is one of nature's most common functional and structural elements, as the backbones of all natural peptides and proteins are composed of amide bonds. Amides are also present in many therapeutic small molecules. The construction of amide bonds using available methods relies principally on dehydrative approaches, although oxidative and radical-based methods are representative alternatives. In nearly every example, carbon and nitrogen bear electrophilic and nucleophilic character, respectively, during the carbon-nitrogen bond-forming step. Here we show that activation of amines and nitroalkanes with an electrophilic iodine source can lead directly to amide products. Preliminary observations support a mechanism in which the polarities of the two reactants are reversed (German, umpolung) during carbon-nitrogen bond formation relative to traditional approaches. The use of nitroalkanes as acyl anion equivalents provides a conceptually innovative approach to amide and peptide synthesis, and one that might ultimately provide for efficient peptide synthesis that is fully reliant on enantioselective methods.