Tuning the Pyridone Scaffold within a Rhodium-NHC Platform for gem-Specific Alkyne Dimerization via a Ligand-Assisted Proton Shuttle Mechanism
Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide A series of mononuclear square-planar Rh{κ 2 N,O -BHetA}(η 2 -coe)(NHC) (BHetA = Bis-Heteroatomic Acidato) complexes have been prepared. Modifications of the pyridonato BHetA-type ligand architecture include 4-Me, 5-Me, 6-Me, 3-Br, 4-Br, 4-OMe, and 5-NO 2 substitutions as well as pyrimidonato, succinimidato, and 2-piperidonato catalysts. Two structural isomers have been observed for the complexes, depending on the stereoelectronic properties of the ligand. The structure–activity relationship has been studied for gem -specific alkyne dimerization via a cooperative ligand-assisted proton shuttle mechanism. Density functional theory calculations have revealed a mechanistic pathway involving the hemilabile coordination of the BHetA ligand, CMD deprotonation, π-alkyne protonation, and reductive elimination. The increase in oxygen basicity imparted by the substituent in the pyridonato ligand is key, the 4-methyl derivative being the most active catalyst. However, a favored iminol–amide tautomerization precludes an increase in catalytic activity for the more basic saturated piperidonato catalyst.
Source: Organometallics
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: G1175115578, G121809054, G1855990336, G2262748287, G2309174360, G2333982261, G2660406951, G279363373, G2825053243, G300979063, G3020948319, G3407200006, G34346518, G3480869486, G3690828678, G3845300180, Catálisis Homogénea por Compuestos Organometálicos, G425668148, G430777504, G5080475149, G5261409311, G5421974903, G5701233768, G5730492914, G6485643232, G7084143925, G8684520763, G8727077623, G8920660035, G897484643, G99296377
OpenAlex ID: W4404327387