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3.A; 3.B
N-(3-(6-(4-((2S)-1,4-Dimethyl-3-oxopiperazin-2-yl)phenylamino)-4-methyl-5-oxo-4,5-dihydropyrazin-2-yl)-2-methylphenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxamide (20); The racemic mixture (12) was subjected to chiral separation on Chiralcel-AD-H (60% isopropanol in heptane, with 0.1% trifluoroacetic acid) to give individual enantiomers at 4.6 minutes (20) ((-) isomer) ([α]D25=-37.8° (c=3.75, CHCl3), mp=181-183° C.) and at 9.2 minutes (19) ((+) isomer) ([α]D25=+38.8° (c=3.57, CHCl3), mp=180-182° C.). Alternatively, the racemic mixture (12) was subjected to chiral separation on Chiralpak AD (75% isopropanol in heptane, at 1 mL/min) and individual enantiomers were collected from 17 to 27 minutes (20) ((-) isomer) and from 27 to 60 minutes (19) ((+) isomer).Alternatively, racemic mixture (4) was subjected to separation on Chiralpak AD (30% i-propanol/heptane 0.1% trifluoroacetic acid) to give individual enantiomers at 5.4 minutes (S-isomer) and 14.9 minutes (R-isomer). The individual isomers 19 and 20 were then prepared using the general synthetic routes described in Example 1 or Example 2.