This patent uses a new class of phase-transfer catalysts called “pentanidium” salts. Chiral PTC Michael additions reported in the patent achieve enantiomeric excesses in the range of 85% to 97% which is very good since chiral PTC Michael additions typically give lower ee than chiral PTC C-alkylations using the same C-H acid compounds.
The Michael acceptors described in the patent include vinyl ketones (often the hardest for achieving high ee), acrylates and chalcones. Methyl vinyl ketone gave 91% ee. That is impressive especially considering that the chiral structure basis of this phase-transfer catalyst is simpler than those of other chiral phase-transfer catalysts.
The inventors note that the chiral pentanidium salts can be used for chiral alkylations and aldol condensations though do not give examples. We hope to see such examples in future patents and we will be very curious to see of the ee’s of the C-alkylations will be higher.
If your company may benefit from improved process performance for strong base reactions, now contact Marc Halpern for the best expertise in industrial PTC string base reactions using inexpensive inorganic bases.
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!).
