For those of you already familiar with the various generations of chiral phase-transfer catalysts, you may think you recognize the structure of the chiral phase-transfer catalyst shown here as belonging to the family of N-anthracenylmethyl cinchona alkaloid quats. However, on close examination, you notice that there is a nitrogen atom on the middle ring, making this an acridinylmethyl quat. The cinchona alkaloid is quinine since the hydroxyl is in a R-configuration (the S-configuration is quinidine) and there is a methoxy on the quinolone ring.
Acridinylmethyl quininium bromide was used in an interesting addition reaction of hydroxylamine to the double bond of a chalcone and chiral ring closure. Three points of interaction are required for the best chiral recognition and when looking at the structures of the starting material and chiral phase-transfer catalyst, it is not hard to envision 2 pi-pi interactions and one hydrogen bonding interaction between the chiral phase-transfer catalyst and the starting material.
Contact Marc Halpern of PTC Organics if your company can benefit from expert choice of phase-transfer catalyst for commercial PTC applications.
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!).
