Up-Scale Synthesis of p -(CH 2 ═CH)C 6 H 4 CH 2 CH 2 CH 2 Cl and p -ClC 6 H 4 SiR 3 by CuCN-Catalyzed Coupling Reactions of Grignard Reagents with Organic Halides

High Resolution Image Download MS PowerPoint Slide Grignard reagents featuring carbanion characteristics are mostly unreactive toward alkyl halides and require a catalyst for the coupling reaction. With the need to prepare p -(CH 2 ═CH)C 6 H 4 CH 2 CH 2 CH 2 Cl on a large scale, the coupling reaction of p -(CH 2 ═CH)C 6 H 4 MgCl with BrCH 2 CH 2 CH 2 Cl was attempted to screen the catalysts, and CuCN was determined to be the best catalyst affording the desired compound in 80% yield with no formation of Wurtz coupling side product CH 2 ═CHC 6 H 4 –C 6 H 4 CH═CH 2 . The p -(CH 2 ═CH)C 6 H 4 Cu(CN)MgCl species was proposed as an intermediate based on the X-ray structure of PhCu(CN)Mg(THF) 4 Cl. p -ClC 6 H 4 MgCl did not react with sterically encumbered R 3 SiCl (R = n -Bu or n -octyl). However, the reaction took place with the addition of 3 mol % CuCN catalyst, affording the desired compound p -ClC 6 H 4 SiR 3 . The structures of p -(CH 2 ═CH)C 6 H 4 CH 2 CH 2 CH 2 MgCl and p -ClC 6 H 4 MgCl were also elucidated, which existed as an aggregate with MgCl 2, suggesting that some portion of the Grignard reagents were possibly lost in the coupling reaction due to coprecipitation with the byproduct MgCl 2 . R 3 SiCl (R = n -Bu or n -octyl) was also prepared easily and economically with no formation of R 4 Si when SiCl 4 was reacted with 4 equiv of RMgCl. Using the developed syntheses, [ p -(CH 2 ═CH)C 6 H 4 CH 2 CH 2 CH 2 ] 2 Zn and iPrN[P(C 6 H 4 - p -SiR 3 ) 2 ] 2, which are potentially useful compounds for the production of PS- block -PO- block -PS and 1-octene, respectively, were efficiently synthesized with substantial cost reductions.