N,N-Bis-(dimethylfluorosilylmethyl)amides of N-organosulfonylproline and sarcosine: synthesis, structure, stereodynamic behaviour and in silico studies

(O -> Si)-Chelate difluorides R3R2NCH(R-1)C(O)N(CH2SiMe2F)(2) (9a-c, R1R2 = (CH2)(3), R-3 = Ms (a), Ts (b); R-1 = H, R-2 = Me, R-3 = Ms (c)), containing one penta-and one tetracoordinate silicon atoms were synthesized by silylmethylation of amides R3R2NCH(R-1)C(O)NH2, subsequent hydrolysis of unstable intermediates R3R2NCH(R-1)C(O)N(CH2SiMe2Cl)(2) (7a-c) into 4-acyl-2,6-disilamorpholines R3R2NCH(R-1)C(O)N(CH2SiMe2O)(2) (8a-c) and the reaction of the latter compounds with BF3 center dot Et2O. The structures of disilamorpholines 8a, c and difluoride 9a were confirmed by an X-ray diffraction study. According to the IR and NMR data, the O -> Si coordination in solutions of these compounds was weaker than that in the solid state due to effective solvation of the Si-F bond. A permutational isomerisation involving an exchange of equatorial Me groups at the pentacoordinate Si atom in complexes 9a-c was detected, and its activational parameters were determined by H-1 DNMR. In silico estimation of possible pharmacological effects and acute rat toxicity by PASS Online and GUSAR Online services showed a potential for their further pharmacological study.