Synthetic approaches to endothelin receptor antagonists in clinical development.

The increasing structural and stereochemical complexity of new drug candidates continues to pose numerous synthetic challenges for pharmaceutical process development. Often the implementation of new methodologies, and/or the novel utilization of existing methodologies becomes an essential aspect of developing cost-effective and practical syntheses for new chemotherapeutics. An excellent case in point, and highlighted in this review, are the novel synthetic processes developed for some of the leading endothelin receptor antagonists currently in clinical development.