Although the same chiral central auxiliaries are attached to the para-positions of the two phenyl rings, their functional group orientations differ noticeably. Additionally, the carbonyl groups on the two phenyl rings are arranged differently. In the M-and P-isomers, the C=O groups are oriented clockwise and counterclockwise, respectively, opposite to the rotation of their parent phenyl rings. These two factors likely contribute to the slipped staircase chirality observed. Interestingly, the two isobutyl groups in the M-isomer face the same direction, while those in the P-isomer face opposite directions, with a remote CH-CH₂ bond angle of approximately 85°. In both (S)-leucine residues of these two targets, a comparison of the two planar units of [C(O)NH] connected to the C(sp³) center of [CH(iBu)(CO₂Et)] shows that the M-isomer follows a Felkin-Ahn-type orientation. However, in the P-isomer, two distinct rotations occur between the [C(O)NH] and [CH(iBu)(CO₂Et)] units, where the C=O group is either aligned with or oriented away from the C*-H bond (where * indicates the chiral center). These conformational differences result in varying distances between the phenyl rings of the M-and P-diastereomers, measuring 4.041 Å and 4.192 Å, respectively, as determined from the centers of the phenyl rings. , and Suzuki-Miyaura C-C coupling . The second building block , (S)-N-((S)-1-(4-bromophenyl)-1phenylbutyl)-2-methylpropane-2-sulfinamide, was also obtained through a three-step process: aryl lithium formation, dehydration, and asymmetric carbonyl addition, with the absolute configuration of the chiral C(sp³) center assigned by following a similar asymmetric induction method reported in the literature. The final step involved a Suzuki-Miyaura cross-coupling reaction between the two building blocks, yielding methyl (4-(8-(4-((S)-1-(((S)-tert-butylsulfinyl)amino)-1-phenylbutyl)phenyl)naphthalen-1-yl)benzoyl)-(R)valinate , which formed crystalline structures suitable for X-ray diffraction analysis (Figure ). Scheme 2. Asymmetric Synthesis of Target 11 by using (R)-Valine/(S)-Sulfinamide Auxiliaries.