An efficient stereoselective synthesis of six stereoisomers of 3, 4-diaminocyclohexane carboxamide as key intermediates for the synthesis of factor Xa inhibitors

An efficient stereoselective route for the preparation of six stereoisomers of tert-butyl ((1R, 2S, 5S)-2-amino-5-(dimethylcarbamoyl)cyclohexyl)carbamate 1 starting from simple 3-cyclohexene-1-carboxylic acid has been described. Stereochemistry of the title compounds was controlled at C2 center by Mitsunobu reaction and at C5 via a base-catalyzed epimerization. Only a limited usage of column chromatography has provided a direct and scalable route for the six stereoisomers.