ABSTRACT
The parent (H(2)N-S-F) and N,N-dialkyl-substituted fluorides of amidosulfoxylic acid (R(2)N-S-F, R=Me or R(2)N=Morph) as well as the related compounds X-S-F (X=CH(3), OH, F, SiH(3), PH(2), SH, Cl) have been investigated with quantum chemical calculations at the ab initio (MP2) level of approximation. The geometries, electronic structures, molecular orbital (MO) energies and NMR chemical shift values have been calculated to evaluate the role and extent of the polarization and delocalization effects in forming of the high-field fluorine NMR resonances within the series of interest. The deltaF magnitudes for all investigated fluorides of amidosulfoxylic acid as well as the deltaN value calculated for Me(2)N-S-F are in the good agreement with the (19)F and (14)N NMR chemical shift values measured experimentally. For the parent compounds, H(2)N-S-F and H(2)N-SO(2)-F, the orientation of principal axes of the magnetic shielding tensors and the corresponding principal sigma(ii) values along these axes have been qualitatively interpreted basing on the analysis of the MO interactions in the presence of the rotating magnetic field.
ABSTRACT
(+/-)-15-Fluoro-11,15-dideoxyprostaglandin E1 and its methyl and ethyl esters were synthesized. Dehydroxyfluorination reaction (+/-)-11-deoxyprostaglandin E1 esters with various reagents based on SF4 was studied. Along with the target 15-fluorides (mixtures of alpha- and beta-epimers), products of allylic shift and dehydration in a ratio dependent on the fluorination agent were shown to be formed. With a morpholinotrifluorosulfuran-tris(morpholine)sulfonium trimethyldifluorosilicate mixture, the maximal excess (70%) of one of the 15-fluoro epimers was achieved. Possible mechanisms of dehydroxyfluorination of (+/-)-11-deoxyprostaglandin E1 esters with dialkylaminoflluorosulfurans were proposed. Methyl esters of 15-alpha-fluoro- and 15-beta-fluoro-11,15-dideoxyprostaglandin E1 exhibited moderate antiaggregation activity in rabbit platelet tests.
