Rhone-poulenc Rorer Pharmaceuticals Inc.

Frederick A Golec

William L Studt

Raymond D Youssefyeh

Matthew R Powers

Mattew R Powers

This invention relates to the stereospecific process for the preparation, separation and purification of hexahydrodibenzofurans which are used in the preparation of the 5HT.sub.3 compounds. More specifically, the present invention relates to a process for the preparation of substantially optically pure cishexahydrodibenzofuran compounds including at least two chiral fused ring centers which comprises the acidic catalyzed stereospecific ring closure by the intra-molecular inversion of a gamma, i.e. 2', carbon atom of a 2-[(2'-leaving group)cycloalkyl]phenol.

Asymmetric synthesis of hexahydrodibenzofurans by stereospecific

This invention is directed to certain dibenzofurancarboxamides and dibenzofurancarboxamide acids and their use as 5HT.sub.3 antagonists having unique CNS, anti-emetic and gastric prokinetic activity void of any significant D.sub.2 receptor binding properties. Further, this invention relates to a process for the synthesis of stereoisomeric compounds having such CNS, anti-emetic and gastric prokinetic activity.

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Merion, PA, United States of America

Frederick A Golec