Tion from the ligands with the precursor [RuI2(p-cymene)]2. The outcomes obtained with ligands 1 and two of R,Sp,Sp configuration are summarized in Table 1 with each other with our previously reported data for ligands 1 and 2 of R,Sp,Rp configuration and those for the original Walphos ligands SL-W001 and SL-W002.1,three The use of ligands (R,Sp,Sp)-1 and (R,Sp,Sp)-2 in the hydrogenation of all substrates (Chart two) resulted in quantitative or nearly quantitative conversion. The regular test substrates (Z)-methyl -acetamidocinnamate (MAC), methyl acetamidoacrylate (MAA), dimethyl itaconate (DMI), and 2-phenylcinnamic acid (PCA) gave only moderate enantiomeric excesses of up to 84 ee (Table 1, entries 1-8). For these substrates the corresponding Walphos ligands SL-W0011 and SL-W002-1 show considerably better functionality (Table 1,dx.doi.org/10.1021/om401074a | Organometallics 2014, 33, 1945-Organometallics Chart two. Substrates Utilised for Catalyst ScreeningArticleentries two, 3, six, and 8). Surprisingly, with 2-methylcinnamic acid (MCA) the opposite trend was observed. Within this case, the use of ligands (R,Sp,Sp)-1 and (R,Sp,Sp)-2 gave items with 89 and 92 ee, respectively, although the corresponding Walphos ligands resulted in only 62 and 83 ee (Table 1, entries 9 and ten).eight,9 Offered the outcomes obtained for MCA, it seemed of interest to investigate the overall performance of ligands (R,Sp,Sp)-1 and (R,Sp,Sp)-2 inside the hydrogenation of your structurally connected and commercially interesting cinnamic acid derivative IPCAD.1885090-83-4 Formula 1a,7 The use of the original Walphos ligands SL-W001-1 and SL-W002-1 within the rhodium-catalyzed hydrogenation of IPCA-D gave merchandise with 94 and 74 ee following isolation (Table 1, entries 11 and 12). For this sterically a lot additional demanding substrate, each values are greater than those obtained with MCA (83 and 62 ee). Having said that, when their biferrocene analogues (R,Sp,Sp)-1 and (R,Sp,Sp)-2 were applied inside the hydrogenation of IPCA-D the opposite trend was seen. In comparison to MCA, the product ee values dropped from 89 and 92 ee to 77 and 88 ee, respectively.The biferrocene ligands (R,Sp,Sp)-1 and (R,Sp,Sp)-2 were employed within the ruthenium-catalyzed hydrogenations of diketone acetylacetone (ACA) along with the -keto ester ethyl 3-oxopentanoate (EOP). High enantiomeric excesses had been obtained (ACA, 98 ee; EOP, 92 ee; Table 1, entries 13-16), but in these instances the corresponding Walphos ligands also performed quite well (ACA, 96 ee; EOP, 93 ee).N-Boc-PEG2-bromide Chemscene In short, the hydrogenation of substrates MCA, ACA, and EOP with biferrocene ligands (R,Sp,Sp)-1 and (R,Sp,Sp)-2 led to items with enantiomeric excesses of 92 .PMID:23659187 Additionally, the worth obtained for MCA (92 ) was substantially greater than that accomplished with either on the two Walphos ligands (83 and 62 ee). A comparison from the ee values listed in Table 1 shows that, overall, the Walphos ligands gave the very best overall performance from the systems tested. Four out on the eight substrates (MAA, IPCA-D, ACA, and EOP) could possibly be hydrogenated with enantiomeric excesses higher than 90 (93-97 ee). On using the ligands (R,Sp,Sp)-1 and (R,Sp,Sp)-2, that are both according to the achiral 2,2-biferrocenediyl backbone, 3 of the substrates (MCA, ACA, and EOP) gave product ee values greater than 90 (92- 98 ee). Nonetheless, on applying ligands (R,Sp,Rp)-1 and (R,Sp,Rp)-2, that are according to the C2-symmetrical 2,2-biferrocenediyl backbone, only one particular substrate (MAC) gave a item with such a higher enantiomeric excess (91 ee) (Table 1, entry 2). It ap.
