Documents WO 02/02508, WO 02/08172 and WO 01/09083 describe chiral octenoic acid derivatives of the general formula (I) as important intermediates especially in the multistage preparation of the renin inhibitor known as “aliskiren” (CAN: 173334-57-1) from Novartis. According to these documents, the chiral phenyl-substituted octenoic acid derivatives are formed from two chiral blocks, one unit being a chiral 3-phenyl-2-isopropylpropyl halide (known from WO 02/02487 and WO 02/02500) and the other unit being a chiral 5-halo-2-isopropylpent-4-enoic acid (described in WO 01/09079 and WO 02/092828), which are combined to give the desired product. The two chiral blocks are prepared separately via complex multistage syntheses, as described in the abovementioned documents. The overall preparation process for the chiral phenyl-substituted octenoic acid derivatives of the general formula (I) is thus very complex, and additionally includes an asymmetric hydrogenation step in which a very expensive homogeneous chiral Rh catalyst which is not readily available is needed, which makes the process very costly overall.
USPTO Backgrounds
USPTO Backgrounds