Asymmetric Synthesis of an MMP-3 Inhibitor Incorporating a 2-Alkyl Succinate Motif
作者:Christopher P. Ashcroft、Stephen Challenger、Andrew M. Derrick、Richard Storey、Nicholas M. Thomson
DOI:10.1021/op034001y
日期:2003.5.1
An efficient and practical synthesis is presented of the pharmaceutically active MMP-3 inhibitor UK-370,106 (1) via an olefination/catalytic asymmetric hydrogenation sequence. Commercially available 5-bromo-2-iodotoluene was converted in two steps to the biarylpropanal equivalent (11), which was reacted with the phosphonosuccinate (10) to selectively afford the trans-b-substituted itaconate (12). Catalytic asymmetric hydrogenation of the itaconate (12) was achieved in good conversion and with 86-96% enantiomeric excess with a range of phosphine-modified rhodium and ruthenium cationic complexes. The resulting enantiomerically enriched 2-alkyl succinate (2) was elaborated to the desired drug substance (1) in two steps. The synthesis benefits from several crystalline intermediates, allowing control of process impurities, and can be operated safely within parameters readily achievable on scale. Investigations into the polymorphic forms of (1) have shown that the compound crystallizes in planar sheets, based on a backbone of hydrogen-bonding amide and acid functionalities, with large hydrophobic pockets formed by the biarylpropyl groups. An understanding of this crystal-packing arrangement has aided the development of crystallization processes allowing complete control over solid form.