“…[ either reduction or oxidation gave the corresponding chiral pyrrolidine 11 a, acid 12 a, and diamine 12 aa. [1] The absolute stereochemistry of the highly substituted quaternary proline derivatives 8 was confirmed by the X-ray crystallographic analysis of 8 c (2S, 3R, 4R, 5S; Figure 2). [1] The absolute stereochemistry of the highly substituted quaternary proline derivatives 8 was confirmed by the X-ray crystallographic analysis of 8 c (2S, 3R, 4R, 5S; Figure 2).…”