The present invention provides an efficient synthesis for the preparation of ((1R,3S)-3-isopropyl-3-{[3-(trifluoromethyl)-7,8-dihydro-1,6-naphthyridin-6(5H)-yl]carbonyl}cyclopentyl)[(3S,4S)-3-methoxytetrahydro-2H-pyran-4-yl]amine and its succinate salt. The present invention additionally provides an efficient syntheses for the preparation of intermediates (3R)-3-methoxytetrahydro-4H-pyran-4-one; (1 S ,4 S )-4-(2,5-dimethyl-1 H -pyrrol-1-yl)-1-isopropylcyclopent-2-ene-1-carboxylic acid; and 3-(trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine; and for the preparation of the precursor (3S,4S)-N-((1S,4S)-4-isopropyl-4-{[3-(trifluoromethyl)-7,8-dihydro-1,6-naphthyridin-6(5H)-yl]carbonyl}cyclopent-2-en-1-yl)-3-methoxytetrahydro-2H-pyran-4-amine. The invention additionally resides in the superior properties of the succinate salt of ((1R,3S)-3-isopropyl-3-{[3-(trifluoromethyl)-7,8-dihydro-1,6-naphthyridin-6(5H)-yl]carbonyl}cyclopentyl)[(3S,4S)-3-methoxytetrahydro-2H-pyran-4-yl]amine.