Organometallics in Process Chemistry by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9783030279615
Publisher: Springer International Publishing

Catalyst technology aided by high-throughput screenings of free ligands in conjunction with Pd precursors is also equally employed for developing systems for advanced cross couplings in pharmaceutical and related fine chemical industries. The concept behind this approach is to increase the probability of identifying a suitable catalyst system quickly. In addition, the upfront catalyst cost associated with the use of a free ligand in conjunction with the Pd precursor might be cheaper than using a pre-catalyst. Although this may have case-by-case process economic advantages, the overall trend appears to be changing. It is here that the next era of cross coupling has begun, not specifically in tuning of the reaction using the first-generation catalyst systems but in the effective conversion of a stable pre-catalyst to the active catalyst and prevention of its deactivation through directed modification of the pre-catalysts [5, 34, 37, 41–43].

Throughout this chapter we would like to help dispel the assumption that a catalyst is a catalyst no matter how it is generated, i.e., in situ vs preformed. We would also like to add to this concept by showing some of the improvements to process economics that have been gained by using stable preformed Pd catalysts by various process development groups, mostly from industry. We aim to do this from the point of view of catalyst activation with precise control of the ligand to metal ratio (M:L). From an engineering point of view, preformed catalyst can be activated to LnPd(0) with a consistent M:L ratio for highly reproducible, consistent, and robust reactions compared to the catalysts derived from the conventional “in situ” technology.

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