CRYSTAL STRUCTURES OF THE DIASTEREOMERIC SALT PAIR OF THE PROSTAGLANDIN INTERMEDIATE 1R,2S(+)-cis-2-HYDROXYCYCLOPENT-4-ENYLACETIC ACID WITH S- and R-1-PHENYLETHYLAMINE

Article abstract of DOI:10.1016/0022-2860(89)85013-6

Crystal structures of an enantiomeric salt pair formed between 1R,2S-cis-2-hydroxycyclopent-4-enylacetic acid (S-HCA) and R(+)-1-phenylethylamine (R-PEA) and the corresponding S-PEA salt have been determined by X-ray crystallography.The S-HCA:R-PEA 1:1 salt (R-HCAPEA hereafter) is orthorhombic, P2₁2₁2₁, with the unit-cell parameters a=5.806(1), b=9.261(1), c=27.624(2) Angstroem and R=0.056 for 1162 reflections at ambient temperature.The S-HCA:S-PEA 1:1 salt (S-HCAPEA) is also orthorhombic, P2₁2₁2₁, with the unit-cell data a=6.034(2), b=11.840(7), c=20.198(11) Angstroem at 170 K, R=0.082 for 1196 data measured at low temperatures (170 K).The R-HCAPEA salt has its two components assembled into an elongated rod-like shape via two-dimensional hydrogen bonding between cations and anions thus forming a well-ordered crystal.In contrast, the cation and anion in the S-HCAPEA salt forms a more globular aggregate and displays orientation disorder in the five-membered ring part of the anion and maintains an essentially one-dimensional hydrogen-bond network, while the total number of hydrogen bonds between cationic and anionic species remains three in both crystals.