Abstract
The selective Heck arylation of acrolein diethyl acetal catalysed by [Pd(NH3)(4)]Cl-2 in the presence of RAME-beta-CD in water as solvent is described. Depending on the base (i.e. NaOAc or HN(i-Pr)(2)) good to high selectivity's towards, respectively, the cinnamaldehydes 2 or the 3-arylpropionic esters 1 were achieved. The results support that depending on the base different palladium intermediate complexes are formed. Using NaOAc, {[ArPdX(H2O)(2)]} complex is preferentially generated giving the cinnamaldehyde 2. On the other hand, in the presence of HN(i-Pr)(2), a L-type ligand, [ArPdX(HN(i-Pr)(2)(H2O)] or [ArPdX(HN(i-Pr)(2)(HN(i-Pr)(2))] will be generated leading to the formation of the 3-mylpropionic ester 1. For the last, coordinated amine participates very probably to the formation of the esters through intramolecular syn p-H elimination. (C) 2013 Elsevier B.V. All rights reserved.