Merck + Co., Inc.

Banyu Pharmaceutical Co. Ltd

Mangzu Zhao

David M Tschaen

Zhiguo Jake Song

Jing Li

Paul N Devine

Richard D Tillyer

Eiichi Mano

The present invention relates to a periodic acid oxidation which converts the penultimate intermediate bearing a primary alcohol to the target endothelin antagonist compound of Formula I having a carboxylic acid.

Oxidation process using periodic acid

The present invention relates to an oxidation which converts a primary or secondary alcohol of Formula II: ##STR1## to an acid or ketone of Formula I: ##STR2## with periodic acid and a catalytic amount of a chromium reagent.

The present invention relates to a TEMPO-catalyzed oxidation of primary alcohols, RCH.sub.2 OH to corresponding carboxylic acids, RCOOH in the presence of catalytic in the presence of catalytic amount of NaClO and stoichiometric amount of NaClO.sub.2 as an oxidant. ##STR1##

Oxidaton of primary alcohols to carboxylic acids with a TEMPO catalyst

This invention relates to a cyclization process useful in the preparation of a key intermediate in the preparation of an endothelin antagonist of the general formula shown below: ##STR1##

Phosphate-mediated cyclization

The present invention relates to an oxidation using sodium chlorite in the presence of a catalytic amount of TEMPO and sodium hypochlorite which converts the penultimate intermediate bearing a primary alcohol to the target endothelin antagonist compound of Formula I having a carboxylic acid ##STR1##

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Edison, NJ, United States of America

Mangzu Zhao