Iron‐Catalyzed Borylation of Propargylic Acetates for the Synthesis of Multisubstituted Allenylboronates

• Published in: Chemistry : a European journal Vol. 29; no. 3; pp. e202203130 - n/a
• Main Authors: Bermejo‐López, Aitor, Kong, Wei‐Jun, Tortajada, Pedro J., Posevins, Daniels, Martín‐Matute, Belén, Bäckvall, Jan‐E.
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 12.01.2023; Wiley Subscription Services, Inc; John Wiley and Sons Inc
• Subjects: Acetates; Acetic acid; Allenes; allenylboronates; Boron; borylation; Catalysis; Chemistry; Chemistry, Multidisciplinary; Chirality; Functional groups; Iron; Oxidation; Oxidation-Reduction; Physical Sciences; propargyl esters; Room temperature; Science & Technology; Stereoisomerism; propargyl esters; HYDROBORATION; CARBOXYLATES; CARBONATES; ENANTIOSELECTIVE SYNTHESIS; ALKYL; borylation; ALLENYL; allenylboronates; ALCOHOLS; CROSS-COUPLING REACTIONS; BORATION; Allenes; iron; EFFICIENT
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202203130

A novel iron‐catalyzed borylation of propargylic acetates leading to allenylboronates has been developed. The method allows the preparation of a variety of di‐, tri‐ and tetrasubstituted allenylboronates at room temperature with good functional group compatibility. Stereochemical studies show that an anti‐SN2’ displacement of acetate by boron occurs; this also allows transfer of chirality to yield enantiomerically enriched allenylboronates. The synthetic utility of this protocol was further substantiated by transformations of the obtained allenylboronates including oxidation and propargylation. Multisubstituted allenylboronates were easily accessed through iron‐catalyzed borylation of propargylic acetates. The reaction is highly efficient, occurs under mild conditions, and is easy to scale up. The reaction is stereospecific and occurs with anti‐SN2‘ displacement of the acetate by boron, which allows a transfer of chirality. Several transformations including propargylation and further additions highlight the synthetic utility of this reaction.