Patent ID: 7915404

Claim:
A method of making a compound of Formula (I): or an enantiomer, diastereomer, or pharmaceutically acceptable salt thereof; comprising reacting a compound of formula (IV): with an acid under reducing conditions, in a non-basic organic solvent, at a temperature between about room temperature and the reflux temperature of the solvent, to provide the compound of Formula (I), wherein Ar is 4-fluorophenyl; ALK is isopropyl or cyclopentyl; R 2 is —CO 2 R 10 or a benzyl group unsubstituted or substituted with one or two —OCH 3 substituents; where R 10 is methyl, ethyl, 2-trimethylsilylethyl, 2-phenylethyl, 1-(1-adamantyl) -1-methylethyl, t-butyl, 1-adamantyl, vinyl, allyl, benzyl, p-methoxybenzyl, p-nitrobenzyl, p-chlorobenzyl, 2,4-dichlorobenzyl, or diphenylmethyl; and P 1 and P 2 are each independently —C 1-4 alkyl, or, alternatively, P 1 and P 2 taken together form —(CH 2 ) 2-3 —.