Carboxylate-Directed Pd-Catalyzed ß-C(sp3)-H Arylation of N-Methyl Alanine Derivatives for Diversification of Bioactive Peptides.

This study presents a Pd(II)-catalyzed method for the ß-C(sp3)-H arylation of N-Cbz- or N-Fmoc-protected N-methyl alanines, providing ready access to building blocks for N-methylated peptide synthesis. For this transformation, the native carboxylate was exploited as the directing group, attributing its success to the use of a monoprotected amino-pyridine ligand. Its synthetic utility was demonstrated by facile generation of nine analogues of the naturally occurring N-methylated cyclic peptide cycloaspeptide A.

Photoredox-Catalyzed Synthesis of ß-Amino Alcohols: Hydroxymethylation of Imines with α-Silyl Ether as Hydroxymethyl Radical Precursor.

Carbon-carbon bond formation is an efficient approach for the synthesis of amino alcohols using two simple starting materials. Herein, we present a novel method for a divergent synthesis of ß-amino ethers and ß-amino alcohols in a sequential one-pot protocol under high-efficiency, mild, and metal- or metal-free conditions. Especially, TMSCH2OPMP was developed as a synthetic equivalent of α-hydroxymethyl radical in an in situ photocatalyzed oxidative PMP group deprotection strategy under air. A preliminary mechanistic investigation provides evidence for reaction mechanism involving a photoinduced α-alkoxy methyl radical and superoxide.