1041865-17-1Relevant articles and documents
A practical synthesis of multifunctional ketones through the fukuyama coupling reaction
Mori, Yoshikazu,Seki, Masahiko
, p. 2027 - 2038 (2007)
A highly efficient, robust and scalable protocol for the synthesis of multifunctional ketones through Fukuyama coupling, i.e., cross-coupling of thiol esters with zinc reagents, has been developed. Treatment of thiol esters with alkylzinc iodides or dialkyl zincs in the presence of palladium on activated carbon (Pd/C) or palladium acetate [Pd(OAc)2] furnished the corresponding ketones in high yields. Evaluation of the properties-activities relationship of the Pd/C-catalyzed reaction has proven that oxidic Pd/C is much more potent than reduced Pd/C in the reaction of thiolactone la with zinc reagent 2a. Based on the dependence of the Pd/C-catalyzed reaction on the nature of Pd/C in combination with the extent of the Pd leaching from Pd/C to the solution, a dual reaction mechanism for the Pd/C-catalyzed Fukuyama coupling reaction, which includes heterogeneous and homogeneous catalytic cycles, was proposed. The marked reduction of the zinc reagents and the use of Pd(OAc) 2 in much smaller amounts were achieved when zinc bromide was added. This supports a hypothesis where a shift of the Schlenk equilibrium from inactive dialkylzincs (R2Zn) to active organozinc species, such as alkylzinc halides (RZnX) and three-coordinate species [(RZnX2) -. (ZnX)+], and generation of the stabilized monomeric Pd complexes during the reaction, may facilitate the reaction.
