The Intermolecular Asymmetric Heck Reaction: Mechanistic and Computational Studies

✍ Scribed by K. K. (Mimi) Hii; Timothy D. W. Claridge; John M. Brown; Andrew Smith; Robert J. Deeth

• Book ID: 101392146
• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: German
• Weight: 206 KB
• Volume: 84
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/1522-2675(20011017)84:10<3043::aid-hlca3043>3.0.co;2-v

✦ Synopsis

Reactive intermediates in the asymmetric Heck reaction between aryl electrophiles and 2,3-dihydrofuran have been identified by NMR and mass spectrometry, with BINAP or the achiral diphosphanes dppp and dppf as ligands. The major cationic species observed is an alkylpalladium produced by addition of PdAr to the alkene followed by two further PdH-mediated isomerisation steps. This last species has been characterised at À 608 by 1 H-, 13 C-, and 31 P-NMR, including HMQC techniques. The regiochemistry of PdAr and PdH addition to the reactant are opposite as defined by the reaction with (2-2 H 1 )-2,3-dihydrofuran. DFT Calculations on the reaction pathway between [CH 2 (PH 2 )]PdPh and 2,3-dihydrofuran reveal several structurally interesting intermediates involving agostic b-H-atom, ipso-Ph or reactant O-atom bonded to the Pd-atom, and elucidate the isomerisation pathway.