Decarboxylation syntheses of transition metal organometallics

Rhodium‐Mediated Decarboxylative Conjugate Addition of Fluorinated Benzoic Acids: Stoichiometric and Catalytic Transformations

“…We focused our attention on chelating bisphosphine ligands as a result of their successful application in rhodium-catalyzed conjugate addition reactions of boronic acids. [2] For the benchmark carboxylate group, we chose 2,6-difluorobenzoate for the following reasons: 1) the favorable combination of an electron-deficient fluorinated aryl group and an electron-rich Rh I center should facilitate decarboxylation from a thermodynamic viewpoint (product stabilization); [15] 2) substitution at both ortho positions would prevent the undesirable ortho C À H activation pathway; 3) the moderate steric hindrance of ortho fluoro substituents would probably promote decarboxylation through ground-state destabilization, but should not significantly hinder subsequent CÀC bond formation through olefin insertion. Furthermore, fluorinated aryl groups are themselves highly useful building blocks in biomedical studies.…”

“…As expected, the aqueous reaction medium was beneficial for optimal yield and selectivity (see Table 1, entry 14). The choice of NaOH as an inorganic additive was also critical for satisfactory results, although its role remains unclear at this stage ( Table 1, entries [15][16][17][18][19][20]. [21] Interestingly, the ligand (R,R)-diop [22] promoted the selective formation of 5 over 4 a (19:1) in 96 % combined yield (Table 1, entry 3).…”