Regioselective C–H Bond Activation of Asymmetric Bis(ylide)s Promoted by Pd. Issue 15 (20th April 2017)

• Record Type: Journal Article
• Authors: Serrano, Elena; Soler, Tatiana; Urriolabeitia, Esteban P.
• Is Part Of: European journal of inorganic chemistry. Issue 15(2017)
• Page Start: 2220
• Page End: 2230
• Publication Date: 2017-04-20
• Subjects: Phosphorus -- Ylides -- Palladium -- C–H activation -- Regioselectivity -- Structure elucidation; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201700030
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : Asymmetric ylide–phosphonium [Ph3 PCHC(O)CH2 PR3 ]Br (PR3 = PPh2 Me4, PPhMe2 5 ) and bis(phosphonium) salts [Ph3 PCH2 C(O)CH2 PR3 ]X2 (PR3 = PPh2 Me6, PPhMe2 7 ) react with PdCl2 (NCMe)2 /NEt3 or Pd(OAc)2, respectively, to give the C, C‐chelating bis(ylide) complexes [PdCl2 {η 2 ‐[Ph3 PCHC(O)CHPR3 ‐κ‐ C, C ]}] (PR3 = PPh2 Me8, PPhMe2 9 ) regioselectively in the erythro form. Starting from8 and9, the corresponding halide‐bridge dimers [Pd(µ‐Cl){η 2 ‐[Ph3 PCHC(O)CHPR3 ‐κ‐ C, C ]}]2 (ClO4 )2 (PR3 = PPh2 Me12, PPhMe2 13 ) can be easily prepared. Complexes12 and13 react with bulky phosphines or diphosphines, undergoing intramolecular Caryl –H bond activation and ortho ‐palladation of the C, C‐chelating bis(ylide), thereby transforming the Pd{η 2 ‐[Ph3 PCHC(O)CHPR3 ‐κ‐ C, C ]} fragment into the Pd(C6 H4 ‐2‐PPh2 CHC(O)CH2 PR3 ‐κ‐ C, C ) moiety in complexes14 –21 . This ortho ‐palladation takes place with complete regioselectivity, because only the PPh3 unit undergoes the C–H bond activation process. Abstract : Coordination of asymmetric P bis(ylide)s with two different PR3 groups, [Ph3 PCHC(O)CHPR3 ], to Pd II forms a four‐membered C, C‐chelate fully diastereoselectively. This asymmetric C, C‐chelate group Pd{η 2 ‐[Ph3 PCHC(O)CHPR3 ]} reacts with phosphines or bis(phosphine)s by a regioselective intramolecular C–H bond activation, affording the ortho ‐palladated fragment Pd{η 2 ‐[C6 H4 ‐2‐PPh2 C(H)C(O)CH2 PR3 ‐κ‐ C, C ]}.