Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

• included [48][49]. These enzymes exhibit distinctly different Fe-containing active sites, typically consisting of two histidines, a carboxylate ligand (e.g., aspartate) and, of course, the ketoglutarate which is bound both via the C-2 ketone and C-1 carboxylate to form 1 (Scheme 1C). Upon its coordination

Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups

• Julius Seumer,
• Nicolai Ree and
• Jan H. Jensen

Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94

• activation, called concerted metal deprotonation (CMD) [5][6][7]. In a concerted mechanism, the Pd atom of the catalyst forms a sigma bond to an aromatic carbon, which increases the acidity of the adjacent (alpha) proton. This allows for the simultaneous abstraction of this proton by a carboxylate ligand. A

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• reductive ligand coupling (RLC) pathway would be suppressed due to reduced fluxionality of the carboxylate ligand on I(III). These important findings are expected to enhance the use of aryl iodane(III)-dicarboxylates for constructing fluorinated azaheterocycles with improved selectivity and control. Oxygen

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• . Later, carboxylate-ligand-assisted C–H bond activation takes place through a concerted metalation–deprotonation transformation to produce the next intermediate. Finally, the corresponding product 142 is formed by a reductive elimination process, along with the regeneration of the active catalytic

Synthesis and metal binding properties of N-alkylcarboxyspiropyrans

• Alexis Perry and
• Christina J. Kousseff

Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154

• for binding divalent metal cations and a modest increase in M2+ binding affinity correlated with increased alkycarboxylate tether length. Keywords: carboxylate ligand; merocyanine; metal binding; photochromism; spiropyran; Introduction Spiropyrans are a class of spiro-fused indolochromene (e.g

• complicated by Cu2+-catalysed spiropyran dimerisation [36]. In the light of the results from Natali et al. [3] – in which evidence for involvement of a carboxylate ligand in metal binding was presented but no comparison was made against a control – it is reassuring to note that incorporation of such a ligand

Latent ruthenium–indenylidene catalysts bearing a N-heterocyclic carbene and a bidentate picolinate ligand

• Thibault E. Schmid,
• Florian Modicom,
• Adrien Dumas,
• Etienne Borré,
• Loic Toupet,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 1541–1546, doi:10.3762/bjoc.11.169

• residues are known to induce ruthenium-complex decomposition, and increase purification complexity [25]. Moreover, in a previous report regarding the synthesis of a dormant ruthenium catalyst bearing a chelating carboxylate ligand, spontaneous chloride/carboxylate exchange with elimination of HCl has been

Synthesis of phenanthridines via palladium-catalyzed picolinamide-directed sequential C–H functionalization

• Ryan Pearson,
• Shuyu Zhang,
• Gang He,
• Nicola Edwards and
• Gong Chen

Beilstein J. Org. Chem. 2013, 9, 891–899, doi:10.3762/bjoc.9.102

• equiv of K2CO3 at 120 °C for 24 h (Table 1, entry 5). Furthermore, an excellent yield was obtained when K2CO3 was replaced with KHCO3 and 0.3 equiv of PivOH was applied (Table 1, entry 7). The most effective carboxylate ligand and solvent was found to be PivOH and toluene, respectively. The