Thermal Decarboxylation of Unsaturated Acids

Highly selective one-step dehydration, decarboxylation and hydrogenation of citric acid to methylsuccinic acid

“…Via this first decarboxylation, itaconic acid ( 2 ) is formed (Scheme 2). 15,16 This unsaturated carboxylic acid can quickly isomerise to mesaconic ( 3 ) and citraconic acid ( 4 ). 15 In the presence of H 2 these isomers can either be hydrogenated to the desired methylsuccinic acid ( 5 ) or further decarboxylated to methacrylic ( 6 ) and crotonic acid.…”

AibA/AibB Induces an Intramolecular Decarboxylation in Isovalerate Biosynthesis by Myxococcus xanthus

“…MG‐CoA is an α/β‐unsaturated carboxylate with respect to the CoA‐thioester, but a β/γ‐unsaturated carboxylate with respect to the γ‐carboxylate group. These compounds are prone to decarboxylation owing to the fact that this reaction can proceed via a six‐membered pericyclic transition state . In the structure with 3MG, we noticed that the ligand assumes a bent conformation, which is a prerequisite to attain such a geometry.…”

“…MG-CoA is an a/b-unsaturated carboxylate with respect to the CoA-thioester, but a b/g-unsaturated carboxylate with respect to the g-carboxylate group.T hese compounds are prone to decarboxylation owing to the fact that this reaction can proceed via as ix-membered pericyclic transition state. [14,15] In the structure with 3MG,w en oticed that the ligand assumes ab ent conformation, which is ap rerequisite to attain such ag eometry.F urthermore,t he hydrophobic environment of the active site will decrease the acidity of the g-carboxylate such that it is likely protonated, as is required for the mechanism shown in Figure 2e [10] leading to decarboxylation from ad eprotonated g-carboxylate group. Cys56 B donates aproton to the C-4p osition and DMA-CoA is formed.…”

AibA/AibB induziert eine intramolekulare Decarboxylierung in der De‐novo‐Biosynthese von Isovalerat aus Myxococcus xanthus

“…Aus der Sicht des CoA‐Esters ist MG‐CoA ein α/β‐ungesättigtes Carboxylat, aber ein β/γ‐ungesättigtes aus der Sicht der γ‐Carboxylatgruppe. Solche Substanzen sind sehr anfällig gegenüber Decarboxylierungen, da diese Reaktion über einen sechsgliedrigen pericyclischen Übergangszustand ablaufen kann . In der 3MG‐Struktur konnten wir zeigen, dass der Ligand eine gebogene Konformation einnimmt, was eine Vorrausetzung für eine solche Geometrie darstellt.…”