890704-23-1Relevant articles and documents
Selective terminal heck arylation of vinyl ethers with aryl chlorides: A combined experimental-computational approach including synthesis of betaxolol
Datta, Gopal K.,Von Schenck, Henrik,Hallberg, Anders,Larhed, Mats
, p. 3896 - 3903 (2007/10/03)
Reaction conditions have been developed for palladium-catalyzed terminal (β-) arylation of acyclic vinyl ethers with high regioselectivity using inexpensive aryl chlorides as starting materials and the P(t-Bu)3 releasing preligand [(t-Bu3)PH]BF4 as the key additive. This swift and straightforward protocol exploits non-inert conditions and controlled microwave heating to minimize handling and processing times and uses aqueous DMF or environmentally friendly PEG-200 as the reaction medium. The selectivity for linear β-product in PEG-200 is slightly higher than in aqueous DMF. DFT calculations support a ligand-driven selectivity rationale, where the electronic and steric influence of bulky P(t-Bu)3 ligand provides improved β-selectivity in the essential insertion step also with electron-rich aryl chlorides. A tentative computational rationalization of the improved selectivity in non-methylated PEG is discussed. Finally the synthetic methodology was used to provide efficient access to linear p-[2- (cyclopropylmethoxy)-ethyl] phenol from p-nitrophenyl chloride, a key intermediate in the synthesis of the β-adrenergic blocking agent Betaxolol.
