Dibromomethane as One‐Carbon Source in Organic Synthesis: Formal Total Synthesis of (±)‐Nephrosteranic Acid

Facile and Sustainable Synthesis of Commendamide and its Analogues

Commendamide, or N-(3-hydroxypalmitoyl)-glycine 1a, is a gut microbiota-derived bioactive metabolite, structurally similar to long-chain N-acyl-amino acids which belong to the complex lipid signaling system known as endocannabinoidome and play important roles in mammals through activation of, inter alia, G-protein-coupled receptors (GPCRs). In this work, we describe a simple, green and economic method for the preparation of commendamide 1a, a GPCR G2A/132 agonist. The developed protocol is general and could also be applied to the synthesis of deuterated commendamide 1b, as well as to other minor microbiota-derived metabolites, such as the analog 2.

An efficient enantioselective approach to multifunctionalized γ-butyrolactone: concise synthesis of (+)-nephrosteranic acid

A short, efficient and novel approach for multifunctionalized γ-butyrolactone paraconic acids and its application to the total synthesis of (+)-nephrosteranic acid from readily available PMB (R)-glycidyl ether as a starting material are described. Key transformations include asymmetric Michael addition catalyzed by chiral diphenylprolinol silyl ether and stereoselective α-methylation.

Bacterial medium-chain 3-hydroxy fatty acid metabolites trigger immunity in Arabidopsis plants

Plants and animals respond to the microbial communities around them, whether in antagonistic or mutualistic ways. Some of these interactions are mediated by lipopolysaccharide—a large, complex, and irregular molecule on the surface of most Gram-negative bacteria. Studying the small mustard plant Arabidopsis , Kutschera et al. identified a 3-hydroxydecanoyl chain as the structural element sensed by the plant's lectin receptor kinase. Indeed, synthetic 3-hydroxydecanoic acid alone was sufficient to produce a response. A small microbial metabolite may thus suffice to trigger immune responses.

Science , this issue p. 178

A protecting-group-free synthesis of (+)-nephrosteranic, (+)-protolichesterinic, (+)-nephrosterinic, (+)-phaseolinic, (+)-rocellaric acids and (+)-methylenolactocin

A collective synthesis of a γ-butyrolactone class of paraconic acids such as (+)-methylenolactocin, (+)-phaseolinic acid, (+)-nephrosteranic acid, (+)-nephrosterinic acid, (+)-rocellaric acid and (+)-protolichesterinic acid is described.

Total synthesis of nominal gobienine A

The lichen-derived glycoconjugate gobienine A is structurally more complex than most glycolipids isolated from higher plants by virtue of the all-cis substituted γ-lactone substructure embedded into its macrocyclic frame. A concise entry into this very epimerization-prone and hence challenging structural motif is presented, which relies on an enantioselective cyanohydrin formation, an intramolecular Blaise reaction, a palladium-catalyzed alkoxycarbonylation, and a diastereoselective hydrogenation of the tetrasubstituted alkene in the resulting butenolide. This strategy, in combination with ring-closing olefin metathesis for the formation of the macrocyclic perimeter, allowed the proposed structure of gobienine A (1) to be formed in high overall yield. The recorded spectral data show that the structure originally attributed to gobienine A is incorrect and that it is not the epimerization-prone ester site on the butanolide ring that is the locus of misassignment; rather, the discrepancy must be more profound.

Stereoselective synthesis of β-(hydroxymethylaryl/alkyl)-α-methylene-γ-butyrolactones

Zinc or a chromium(II) source with 3-(bromomethyl)furan-2(5H)-one (3) and an aldehyde gives β-(hydroxymethylaryl/alkyl)-α-methylene-γ-butyrolactones 5 in good yields and high diastereoselectivities. The methodology is demonstrated in concise syntheses of (±)-hydroxymatairesinol (8) and (±)-methylenolactocin (10) by subsequent arylboronate conjugate addition and translactonization, respectively.