Unusual Course of the Reaction of Allyl Phosphine Oxides with the Grundmann Ketone

<div><p></p><p>This article describes efficient preparation of isomeric allyl phosphine oxides possessing a protected cyclohexanediol fragment. Their base-catalyzed interconversions are examined and reactions with the Grundmann ketone provide an adduct containing the rearranged vinyl phosphine oxide moiety, instead of 19-norvitamin D₃ analogs, the expected products of the Horner–Wittig process.</p> </div

Rotamers in Crystal Structures of Xylitol, D-Arabitol and L-Arabitol

Rotamers are stereoisomers produced by rotation (twisting) about σ bonds and are often rapidly interconverting at room temperature. Xylitol—massively produced sweetener—(2R,3r,4S)-pentane-1,2,3,4,5-pentol) forms rotamers from the linear conformer by rotation of a xylitol fragment around the C2–C3 bond (rotamer 1) or the C3–C4 bond (rotamer 2). The rotamers form two distinguishable structures. Small differences in geometry of rotamers of the main carbon chain were confirmed by theoretical calculations; however, they were beyond the capabilities of the X-ray powder diffraction technique due to the almost identical unit cell parameters. In the case of rotamers of similar compounds, the rotations occurred mostly within hydroxyl groups likewise rotations in L-arabitol and D-arabitol, which are discussed in this work. Our results, supported by theoretical calculations, showed that energetic differences are slightly higher for rotamers with rotations within hydroxyl groups instead of a carbon chain

Seco-B-Ring Steroidal Dienynes with Aromatic D Ring: Design, Synthesis and Biological Evaluation

Continuing our structure-activity studies on the vitamin D analogs with the altered intercyclic seco-B-ring fragment, we designed compounds possessing dienyne system conjugated with the benzene D ring. Analysis of the literature data and the docking experiments seemed to indicate that the target compounds could mimic the ligands with a good affinity to the vitamin D receptor (VDR). Multi-step synthesis of the C/D-ring building block of the tetralone structure was achieved and its enol triflate was coupled with the known A-ring fragments, possessing conjugated enyne moiety, using Sonogashira protocol. The structures of the final products were confirmed by NMR, UV and mass spectroscopy. Their binding affinities for the full-length human VDR were determined and it was established that compound substituted at C-2 with exomethylene group showed significant binding to the receptor. This analog was also able to induce monocytic differentiation of HL-60 cells

Synthesis of 9‑Alkylated Calcitriol and Two 1α,25-Dihydroxy-9-methylene-10,19-dihydrovitamin D₃ Analogues with a Non-natural Triene System by Thermal Sigmatropic Rearrangements

1α,25-(OH)₂-9α-Methylvitamin D₃ (<b>4</b>), the first known analogue of the natural hormone 1α,25-(OH)₂D₃ (<b>3</b>) with an alkyl substituent at C-9, and two 1α,25-(OH)₂-9-methylene-10,19-dihydrovitamin D₃ analogues (<b>7</b> and <b>8</b>) with an unprecedented non-natural triene system were synthesized by thermal isomerization of 1α,25-(OH)₂-9-methylprevitamin D₃ (<b>6</b>). Three alternative approaches (Sonogashira, Stille, or stereoselective dehydration of a tertiary propargyl alcohol) have been successfully used to construct the dienyne precursors of previtamin <b>6</b> possessing two methyl groups capable of participating in the [1,7]-sigmatropic hydrogen shift

Synthesis of New Cisplatin Derivatives from Bile Acids

A series of bile acid derived 1,2- and 1,3-diamines as well as their platinum(II) complexes were designed and synthesized in hope to get a highly cytotoxic compound by the combination of two bioactive moieties. All complexes obtained were subjected to cytotoxicity assays in vitro and some hybrid molecules showed an expected activity