A Practical Access to New Pyrazole SKF-96365 Analogues as Potential Store-Operated Calcium Entry (SOCE) Inhibitors

The racemic synthesis in four steps of pyrazole SKF-96365 analogues without substituent (CF₃ group) on the pyrazole platform was realized in moderate to good yields. The separation of (±) hydroxyl enantiomers 4 was developed successfully using the method of "half-concentration" with commercial (+)-(1S)- and (-)-(1R)-10-camphorsulfonic acid (CSA) followed by neutralization of diastereomers with MeONa in dry MeOH solution. With the pure enantiomers (-)-(1S)-4b and (+)-(1R)-4b, initial attempts to obtain the crystallized (-)-(1S)-7d and (+)-(1R)-7d after treatment of intermediate 6d with a solution of 1M HCl (for precipitation of hydrochloride salt 7d) failed. We have also investigated the effects of compounds 7(a-d) on endoplasmic reticulum (ER) Ca²⁺ and SOCE on PLP-B lymphocyte cell line and compound 7d was identified as a better SOCE inhibitor than SKF-96365. This preliminary SAR study showed that the MeO group in para-position of the phenethyl-1H-pyrazolium skeleton or for the Cbeta-phenylpropoxy side chain of 7 influenced the SOCE activity.