“…[12][13][14][15] Recently we have reported on the synthesis of racemic dioxadrol derivatives bearing various substituents (NR 2 , OR, @O, F) in position 4 of the piperidine ring. [16][17][18] It was shown that like-configuration (RS/RS) of the ring junction, that is, the same configuration of the 2-position of the piperidine ring and 4-position of the dioxolane ring, and axial orientation of the C-4-substituent (also RS-configuration) are crucial for high NMDA receptor affinity. In particular, 4-oxo [(±)-4], 4-hydroxy [(±)-5], 4-fluoro [(±)-6], and 4,4-difluoro [(±)-7] derivatives of dioxadrol [(±)-3] with the same configuration at all centers of chirality reveal promising NMDA receptor affinity of 470, 44, 27, and 81 nM, respectively.…”