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Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
Published on: November 30, 2022
Borylene-based functionalization of iron-alkynyl-σ-complexes and stepwise reversible metal-boryl-to-borirene
Holger Braunschweig1, Qing Ye, Krzysztof Radacki
1Institut für Anorganische Chemie, Bayerische Julius-Maximilians-Universität Würzburg Am Hubland, 97 074 Würzburg, Germany. h.braunschweig@mail.uni-wuerzburg.de
Abstract:
Thermally induced chemoselective borylene transfer from [(OC)(5)Mo=BN(SiMe(3))(2)] (2a) to the carbon-carbon triple bond of an iron dicarbonyl alkynyl complex [(η(5)-C(5)Me(5))Fe(CO)(2)C≡CPh] (3) led to the isolation of an iron aminoborirene complex [(η(5)-C(5)Me(5))(OC)(2)Fe{μ-BN(SiMe(3))(2)C=C}Ph] (4) in satisfactory yield. Room temperature photolysis of 4 resulted in an unprecedented rearrangement and a concurrent decarbonylation, affording the novel C(2) side-on coordinated iron boryl complex [(η(5)-C(5)Me(5))(OC)FeBN(SiMe(3))(2)(η(2)-CC)Ph] (5). Carbonylation of 5 under CO atmosphere at ambient temperature yielded [(η(5)-C(5)Me(5))(OC)(2)FeBN(SiMe(3))(2)CCPh] (6), which is an isomer of 4. Decarbonylation of 6 at 80 °C led to 5, which could be upon introduction of CO gas further converted into 4 under same conditions. Reaction of 5 with PMe(3) at 80 °C yielded the phosphane complex [(η(5)-C(5)Me(5))(OC)(PMe(3))Fe{μ-BN(SiMe(3))(2)C=C}Ph] (7). All above-mentioned iron complexes 4-7 were isolated as air and moisture sensitive crystalline solids in good yields and have been fully characterized in solution and by X-ray crystallography. Quantum chemical calculations using density functional theory (DFT) have been carried out to understand the mechanisms of the experimentally observed reactions and to analyze the bonding situation in the molecules 4-7.
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