Structural analysis and biological activities of C25-amino and C25-nitro vitamin D analogs

Intense synthetic efforts have been directed towards the development of noncalcemic analogs of 1,25-dihydroxyvitamin D₃. We describe here the structural analysis and biological evaluation of two derivatives of 1,25-dihydroxyvitamin D₃ with modifications limited to the replacement of the 25-hydroxyl group by a 25-amino or 25-nitro groups. Both compounds are agonists of the vitamin D receptor. They mediate biological effects similar to 1,25-dihydroxyvitamin D₃, the 25-amino derivative being the most potent one while being less calcemic than 1,25-dihydroxyvitamin D₃. The in vivo properties of the compounds make them of potential therapeutic value.

On the mechanism of the dyotropic expansion of hydrindanes into decalins

A combined computational/experimental approach has revealed key mechanistic aspects in a recently reported dyotropic expansion of hydrindanes into decalins. While computer simulations had already anticipated the need for acid catalysis for making this reaction feasible under the mild conditions used in the laboratory, this work places the dyotropic step not into the reaction flask but at a later step, during the work up instead. With this information in hand the reaction has been optimized by exploring the performance of different activating agents and shown to be versatile, particularly in steroid related chemistry due to the two scaffolds that this reaction connects. Finally, the scope of the reaction has been significantly broadened by showing that this protocol can also operate in the absence of the fused six-member ring.

Development of novel Gemini-cholesterol analogues for Retinoid-related Orphan Receptor

Retinoic-acid-related Orphan Receptors (RORs) regulate maintenance of the circadian rhythm and immune response among others and are involved in increasing number of pathologies including autoimmune diseases, cancer and neurological disorders...

Vitamin D analogues exhibit antineoplastic activity in breast cancer patient-derived xenograft cells

Despite advances in breast cancer (BC) treatment, its mortality remains high due to intrinsic or acquired resistance to therapy. Several ongoing efforts are being made to develop novel drugs to treat this pathology with the aim to overcome resistance, prolong patient survival and improve their quality of life. We have previously shown that the non-hypercalcemic vitamin D analogues EM1 and UVB1 display antitumor effects in preclinical studies employing conventional cell lines and animal models developed from these cells. In this work, we explored the antitumor effects of EM1 and UVB1 employing BC cells derived from patient-derived xenografts (PDXs), which are a powerful preclinical tool for testing new drugs. We demonstrated that the analogues reduced the viability of HER2-positive and Triple Negative BC-PDXs. Moreover, using an in vitro model of acquired resistance to Trastuzumab-emtansine, UVB1 displayed anti-proliferative actions under 2D and 3D culture conditions. It inhibited both formation and growth of established organoids. In addition, a direct correlation between UVB1 antitumor effects and VDR expression in PDXs was found. In conclusion, all the results reinforce the potential use of these vitamin D analogues as antitumor agents to treat HER2-positive and Triple Negative BC.

Easy Access to Polyfunctionalized Chiral Decalins

An unexpected ring expansion that converts hydrindanes into decalins via an unprecedented dyotropic reaction involving a mesylate group has been observed, and this paved the way for easy access to polyfunctionalized chiral decalins. These polyfunctionalized chiral decalins can be very useful building blocks for the synthesis of the thia analogues of many natural compounds. They can also be used in asymmetric catalysis and also in the synthesis of the new analogues of vitamin D with a modified D ring and side chain. The use of chiral sulfoxide ligands for asymmetric catalysis or asymmetric sulfur ylide-mediated epoxidation of carbonyl compounds is a very important topic in the field of organic chemistry, hence our results could be useful to the scientific community.

Crystal structure of (20S)-21-[4-(2-hy-droxy-propan-2-yl)-1H-1,2,3-triazol-4-yl]-20-(4-methyl-pent-yl)-5-pregnen-3β-ol with an unknown solvate

In the title cholesterol analogue, [systematic name: (3S,8S,9S,10R,13S,14S,17R)-17-{(S)-1-[4-(2-hy-droxy-propan-2-yl)-1H-1,2,3-triazol-1-yl]-6-methyl-heptan-2-yl}-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetra-deca-hydro-1H-cyclo-penta-[a]phenanthren-3-ol] C32H53N3O2, a new chain, including an inter-mediate triazole and a tertiary hydroxyl group in the terminal position, has been added at position 20 inducing a change in its stereochemistry. In the crystal, mol-ecules are linked by O-H⋯O and O-H⋯N hydrogen bonds, forming layers lying parallel to (-201) and enclosing R44(36) ring motifs. The isopropyl group is disordered about two positions with a refined occupancy ratio of 0.763 (5):0.237 (5). A region of disordered electron density was corrected for using the SQUEEZE routine in PLATON (Spek (2015). Acta Cryst. C71, 9-18). The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule(s).

A more reliable synthesis of a Gemini vitamin D analog, a potentially effective chemotherapeutic agent for the treatment of colorectal carcinomas

After a serendipitous synthesis of a potentially effective chemotherapeutic agent for the treatment of colorectal carcinomas, a more reliable synthetic method is now described using our building blocks containing stereodefined stereochemistry at C-20.

From Hydrindane to Decalin: A Mild Transformation through a Dyotropic Ring Expansion

An unexpected ring expansion converting hydrindane cores into decalins has been observed. The process occurs under very mild conditions and with exquisite transfer of chiral information. The ring expansion provides access to decorated decalins with complete stereocontrol. The reaction mechanism is studied in order to gain insight into the underlying causes for the low thermal requirements in this reaction and the nature of the chirality transfer process. Interestingly, both result from an unprecedented dyotropic reaction involving a mesylate group.

Crystal structure of (1R,3aR,7aR)-1-{(S)-1-[(2R,5S)-5-(3-hy-droxy-pentan-3-yl)tetra-hydro-furan-2-yl]eth-yl}-7a-methyl-2,3,3a,4,5,6,7,7a-octa-hydro-1H-inden-4-one

The title compound, C21H36O3, contains an oxolane ring, and six defined stereocentres and may serve as a useful synthon for the synthesis of calcitriol analogues. The configurations of the chiral C atoms of the side chain were unambiguously established in the refinement. In the crystal, C-H⋯O and extremely weak O-H⋯O hydrogen bonds arising from the sterically hindered alcohol group link the mol-ecules into a three-dimensional network.

An improved methodology for the synthesis of 1α,25-dihydroxy-20-epi-vitamin D3 (MC 1288) and Gemini analog Ro-438-3582

Control over the C-20 stereochemistry allows a versatile method to introduce novel side-chains into the vitamin D scaffold.