A practical synthesis for the core structure of a family of selective prostaglandin D2 receptor antagonists.

A convergent synthesis was developed for the production of the core structure of prostaglandin D(2) receptor antagonists for the treatment of allergic rhinitis. The key steps in this synthesis were a highly diastereoselective alkylation of (+)-nopinone, a chemo- and stereoselective reduction of an oxime to an amine, and a well-controlled reduction of an aminoalkyne to a (Z)-olefin.