Phase-transfer catalysis has been used for Suzuki Coupling rather often. Strong nucleophilic bases such as alkoxides are not needed and carbonate is enough (with PTC and without). We have reported PTC Suzuki with carbonate before (see http://phasetransfercatalysis.com/ptc_reaction/ptc-suzuki/) and it has even been used in academic student labs (see https://www.ocf.berkeley.edu/~jmlvll/lab-reports/suzuki/suzuki.pdf).
In this patent, PTC Suzuki was successful in the coupling shown using methyl 5-bromothiophene-2-carboxylate (91% yield) and also methyl 5-bromofuran-2-carboxylate (89% yield). When PTC was NOT used for 7 Suzuki couplings using esters in this patent (also in the presence of carbonate), the yields were in the range of only 33% to 60%. The yields for non-esters without PTC in the presence of carbonate were high.
Although it is not stated, it is possible that the use of PTC is advantageous for the Suzuki reaction of esters while avoiding hydrolysis before the coupling takes place. This is just speculation. Input from our readers is welcome.
If your company can benefit from low-cost high-performance green chemistry using phase-transfer catalysis, now contact Marc Halpern of PTC Organics.
About Marc Halpern
Dr. Halpern is founder and president of PTC Organics, Inc., the only company dedicated exclusively to developing low-cost high-performance green chemistry processes for the manufacture of organic chemicals using Phase Transfer Catalysis. Dr. Halpern has innovated PTC breakthroughs for pharmaceuticals, agrochemicals, petrochemicals, monomers, polymers, flavors & fragrances, dyes & pigments and solvents. Dr. Halpern has provided PTC services on-site at more than 260 industrial process R&D departments in 37 countries and has helped chemical companies save > $200 million. Dr. Halpern co-authored five books including the best-selling “Phase-Transfer Catalysis: Fundamentals, Applications and Industrial Perspectives” and has presented the 2-day course “Practical Phase-Transfer Catalysis” at 50 locations in the US, Europe and Asia.
Dr. Halpern founded the journal “Industrial Phase-Transfer Catalysis” and “The PTC Tip of the Month” enjoyed by 2,100 qualified subscribers, now beyond 130 issues. In 2014, Dr. Halpern is celebrating his 30th year in the chemical industry, including serving as a process chemist at Dow Chemical, a supervisor of process chemistry at ICI, Director of R&D at Sybron Chemicals and founder and president of PTC Organics Inc. (15 years) and PTC Communications Inc. (20 years). Dr. Halpern also co-founded PTC Interface Inc. in 1989 and PTC Value Recovery Inc. in 1999. His academic breakthroughs include the PTC pKa Guidelines, the q-value for quat accessibility and he has achieved industrial PTC breakthroughs for a dozen strong base reactions as well as esterifications, transesterifications, epoxidations and chloromethylations plus contributed to more than 100 other industrial PTC process development projects.
Dr. Halpern has dedicated his adult life to his family and to phase-transfer catalysis (in that order!).
