Figure 4.

Schematic representation of the (S,S)-diastereomers molecular units present in the crystal structures of compounds 3 and 4 (note: the (S,R)-diastereomer molecules present in the asymmetric units were omitted for clarity). Asymmetric carbon centres are depicted by an asterisk and the bonds are in light yellow. Non-hydrogen atoms are represented as thermal ellipsoids drawn at the 50% probability level and hydrogen atoms as small spheres with arbitrary radii.