A stereoselective construction of a cis-1,2-oxazadecaline skeleton using a substrate-controlled intramolecular oxy-Michael addition of tyrosine-derived hydroxylamines

Formation of Bridged Disulfide in Epidithiodioxopiperazines

Epidithiodioxopiperazine (ETP) alkaloids, featuring a 2,5-diketopiperazine core and transannular disulfide bridge, exhibit a broad spectrum of biological activities. However, the structural complexity has prevented efficient chemical synthesis and further clinical research. In the past few decades, many achievements have been made in the biosynthesis of ETPs. Here, we discuss the biosynthetic progress and summarize them as two comprehensible metabolic principles for better understanding the complex pathways of α, α'- and α, β'-disulfide bridged ETPs. Specifically, we systematically outline the catalytic machineries to install α, α'- and α, β'-disulfide by flavin-containing oxygenases. This concept would contribute to the medical and industrial applications of ETPs.

Natural products with 1,2-oxazine scaffold: occurrence, chemical diversity, bioactivity, synthesis, and biosynthesis

Covering: up to the end of July, 20231,2-Oxazine is a heterocyclic scaffold rarely found in natural products and is characterized by a directly connected N-O bond in a six-membered ring. Since the discovery of geneserine, the first 1,2-oxazine-containing natural product (1,2-oxazine NP) being isolated from Calabar bean (Physostigma venenosum) in 1925, a total of 76 naturally occurring 1,2-oxazine NPs have been isolated and identified from various sources, which have attracted the attention of researchers in the field of natural product chemistry, organic synthesis, biosynthesis, and pharmacology. This review summarizes the chemical family of 1,2-oxazine NPs, focusing on their source organisms, structural diversities, chemical synthesis, and biosynthesis.

Asymmetric Formal Synthesis of Trichodermamides B and C

An asymmetric formal synthesis of trichodermamides B and C was achieved in 15 steps based on a tyrosine ester chiral-pool approach. Key features of this synthesis include stereoselective construction of a cis-1,2-oxazadecaline core by an acid-mediated tandem deprotection–intramolecular oxy-Michael reaction, oxime ether formation via an N-bromination–elimination sequence, and diene construction by a palladium-catalyzed demonomethylcarbonation.

Tyrosine-Specific Modification via a Dearomatization-Rearomatization Strategy: Access to Azobenzene Functionalized Peptides

Azobenzene functionalized peptides are of great importance in photoresponsive biosystems and photopharmacology. Herein, we report an efficient approach to prepare azobenzene functionalized peptides through late-stage modification of tyrosine-containing peptides using a dearomatization-rearomatization strategy. This approach shows good chemoselectivity and site selectivity as well as sensitive group tolerance to various peptides. This method enriches the postsynthetic modification toolbox of peptides and has great potential to be applied in medicinal chemistry and chemical biology.