Copper‐Catalyzed C−P Cross‐Coupling of (Cyclo)alkenyl/Aryl Bromides and Secondary Phosphine Oxides with in situ Halogen Exchange. Issue 24 (22nd June 2021)

• Record Type: Journal Article
• Authors: Woźnicki, Paweł; Stankevič, Marek
• Is Part Of: European journal of organic chemistry. Issue 24(2021)
• Page Start: 3484
• Page End: 3491
• Publication Date: 2021-06-22
• Subjects: Catalysis -- Copper -- Cross-coupling -- Halogen exchange -- Organophosphorus; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202100456
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: An efficient protocol for concurrent tandem halogen exchange/C−P cross‐coupling of cycloalkenyl bromides and secondary phosphine oxides has been developed. The catalytic system is based on cheap and air‐stable copper(I) iodide as the precatalyst, commercially available N, N' ‐dimethylethylenediamine as the ligand, and Cs2 CO3 or K2 CO3 as the base. The use of sodium iodide as an additive reduces the excessive use of organic bromides to near‐stoichiometric by promoting the in situ transformation to the corresponding iodides. Diarylphosphine oxides undergo cycloalkenylation with 35–99 % yields and dicyclohexylphosphine oxide with 30–53 % yields. In the case of acyclic alkenyl bromides the cross‐coupling products undergo conjugate addition of diphenylphosphine oxide and satisfying yields are observed only for internal olefins. In the case of aryl bromides satisfying yields (43–72 %) are observed only for sterically unhindered arenes or arenes possessing an ortho ‐directing group. Cycloalkenylphosphine oxides prepared in the cross‐coupling reaction undergo base‐catalyzed and base‐promoted conjugate addition to give bis(phosphinoyl)cycloalkanes. Abstract : A protocol for copper‐catalyzed halogen exchange/C−P cross‐coupling between (cyclo)alkenyl/aryl bromides and secondary phosphine oxides has been developed. The addition of sodium iodide increases the yield of the cross‐coupling by promoting in situ halogen exchange of organic bromides to the corresponding iodides.