Chirotech

Address Chirotech, Cambridge Science Park, Milton Road ... 

Dowpharma, Chirotech Technology Limited, 162 Cambridge Science Park, Milton... 

With tethering technology, immobilized Rh(DiPFc) catalyst, a veiy selective hydrogenation catalyst was developed by Engelhard (26) and Chirotech (27). Rh(DiPFc)(COD)BF4 is one of most interesting homogeneous catalysts due to its chemo-selectivity and sulfur tolerant behavior. The anchored complex y-... 

Chirotech Technology Limited The Dow Chemical Company 321 Cambridge Science Park Milton Road Cambridge CB4 0WG UK... 

M.J. Burk, F. Bienewald, A. Zanotti-Gerosa (Chirotech Technology Limited), WO 99/52852. 

Two technical applications of C = N-X substrates have been reported. Noyori s Ru-PP-NN catalyst system was successfully applied in a feasibility study by Dow Chirotech for the hydrogenation of a sulfonyl amidine [77], while Avecia showed the commercial viability of its CATHy catalyst based on a pentamethyl cyclopentadienyl Rh complex for the reduction of phosphinyl imines [78] (Fig. 34.11). 

Dow/Chirotech [35, 36], Topcro Pharma [37] as well as by Solvias [38] using Rh-DuPhos catalysts (Fig. 37.6). Besides these successful examples, a process using Rh-DuPhos was abandoned because of reproducibility problems due to impurities carried over from the preceding step, and because of concerns about the toxicity of 2-nitropropane, even though ee-values of 99% were achieved [39]. 

Rh / Me-DuPhos no details available pilot processes, Dow Chirotech [36]... 

The hydrogenation was carried out on 12-kg scale for Pfizer by Dow/Chirotech, using a cationic Rh-DuPhos catalyst [79] and on 250-kg scale by PPG-Sipsy with a Ru-biphep complex [80]. Both catalysts achieved very high enantioselectivities and medium activities. 

The hydrogenation of a number of aromatic ketones is shown in Figure 37.30. Noyori s very effective Ru-diphosphine-diamine technology was developed by several companies. It is not clear on which scale the processes developed by Takasago (dm-binap = 3,5-xylyl-binap) [16] and Dow/Chirotech [109-111] for the reduction of substituted acetophenones are actually applied commercially. Using the Xyl-PhanePhos-dpen catalyst, a highly efficient bench-scale process was developed for the hydrogenation of p-fluoroacetophenone (ee 98%, TON 100000, TOF 50000 IT1 at r.t., 8 bar) [109]. Ru-P-Phos (licensed to Johnson Matthey [112]) achieved ee-values >99.9% and TON up to 100000 for sev-... 

Dow/Chirotech Proprietary chiral ligands, process R D, custom manufacturing. Several production processes, many pilot- and bench-scale processes [111],... 

This catalyst is commercially available from Strem or Chirotech. 

Kissel, Ramsden, and other researchers at Pfizer and Chirotech jointly published a novel chiral synthesis of pregabalin (2) in 2003 based on asymmetric hydrogenation (Burk et al., 2001, 2003). Their synthesis started with the condensation of isobutyralde-hyde with acrylonitrile under Baylis-Hillman conditions to give allylic alcohol 65. This alcohol was activated as the carbonate 66 and subjected to palladium-catalyzed car-bonylation conditions to give cyanoester 67. The ester 67 was hydrolyzed and converted to... 

Scheme 16.18. The Pfizer/Chirotech asymmetric hydrogenation route to pregabalin (2).

Dowpharma (USA) Angus Chemical, UK Ascot, UK Chirotech, UK CMS plant, UK Collaborative BioAlliance, NY, USA Haltermann, De Hampshire, USA Mitchell Cotts, UK... 

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