TY - JOUR
T1 - Synthesis of fluorous sulfur/carbon/sulfur pincer ligands and palladium complexes
T2 - New catalyst precursors for the Heck reaction
AU - Da Costa, Rosenildo
AU - Jurisch, Markus
AU - Gladysz, John A.
PY - 2008
Y1 - 2008
N2 - Reactions of 1,3-C6H4(CH2Br)2 and the thiols HSCH2CH2Rfn (Rfn=(CF2)n−1CF3; n=8, 10), or the dithiol 1,3-C6H4(CH2SH)2 and ICH2CH2Rfn, in the presence of carbonate or NaOEt (70–78°C) give the title ligands 1,3-C6H4(CH2SCH2CH2Rfn)2 (4-Rf8, 58–61%; 4-Rf10, 49–50%). Reactions of 4-Rfn and Pd(OC(O)CF3)2 or (PhCN)2Pd(Cl)2 (80°C) afford the title complexes (n/X=8/OC(O)CF3 (5-Rf8), 44%; 10/OC(O)CF3, 58%; 8/Cl (6-Rf8), 45%; 10/Cl, 79%). Both 5-Rf8 and 6-Rf8 are effective catalyst precursors for the Heck reaction of iodobenzene and methyl acrylate (0.21–0.23mol%, DMF, i-Pr2NEt, 100–125°C). However, no active catalyst can be recycled by a subsequent extraction with fluorous solvents. Rather, activity remains in the reddish DMF phase, and is quenched by the addition of mercury. Palladium nanoparticles are visible by transmission electron microscopy. These, or low valent species derived therefrom, are believed to be the active catalysts, in accord with other recent studies involving related non-fluorous and fluorous palladacycles. The CF3C6F11/toluene partition coefficients of representative compounds are determined.
AB - Reactions of 1,3-C6H4(CH2Br)2 and the thiols HSCH2CH2Rfn (Rfn=(CF2)n−1CF3; n=8, 10), or the dithiol 1,3-C6H4(CH2SH)2 and ICH2CH2Rfn, in the presence of carbonate or NaOEt (70–78°C) give the title ligands 1,3-C6H4(CH2SCH2CH2Rfn)2 (4-Rf8, 58–61%; 4-Rf10, 49–50%). Reactions of 4-Rfn and Pd(OC(O)CF3)2 or (PhCN)2Pd(Cl)2 (80°C) afford the title complexes (n/X=8/OC(O)CF3 (5-Rf8), 44%; 10/OC(O)CF3, 58%; 8/Cl (6-Rf8), 45%; 10/Cl, 79%). Both 5-Rf8 and 6-Rf8 are effective catalyst precursors for the Heck reaction of iodobenzene and methyl acrylate (0.21–0.23mol%, DMF, i-Pr2NEt, 100–125°C). However, no active catalyst can be recycled by a subsequent extraction with fluorous solvents. Rather, activity remains in the reddish DMF phase, and is quenched by the addition of mercury. Palladium nanoparticles are visible by transmission electron microscopy. These, or low valent species derived therefrom, are believed to be the active catalysts, in accord with other recent studies involving related non-fluorous and fluorous palladacycles. The CF3C6F11/toluene partition coefficients of representative compounds are determined.
U2 - 10.1016/j.ica.2007.11.016
DO - 10.1016/j.ica.2007.11.016
M3 - Article
VL - 361
SP - 3205
EP - 3214
JO - Inorganica Chimica Acta
JF - Inorganica Chimica Acta
IS - 11
ER -