Synthesis of Demissidine Analogues from Tigogenin via Imine Intermediates.

A five-step transformation of a spiroketal side chain of tigogenin into an indolizidine system present in solanidane alkaloids such as demissidine and solanidine was elaborated. The key intermediate in the synthesis was spiroimine readily obtained from tigogenin by its RuO oxidation to 5,6-dihydrokryptogenin followed by amination with aluminum amide generated in situ from DIBAlH and ammonium chloride. The mild reduction of spiroimine to a 26-hydroxy-dihydropyrrole derivative and subsequent mesylation resulted in the formation of 25-epidemissidinium salt or 23-sulfone depending on reaction conditions.

The synthesis of solasodine F-homo-analogues.

Solasodine derivatives continue to be attractive targets for synthetic chemists due to their interesting biological properties. Herein, we report a concise synthesis of solasodine analogues containing the seven-membered F ring from diosgenin. The key intermediate in the synthesis of 26a-homosolane derivatives was 26-cyanopseudodiosgenin.

Synthesis of novel galeterone derivatives and evaluation of their in vitro activity against prostate cancer cell lines.

Prostate cancer is one of the main causes of male cancer-related deaths worldwide and the suppression of androgen receptor signalling is established as an effective strategy for the treatment. A series of galeterone analogues including several steroid-fused azacycles, as well as 17-(benzimidazol-1-ylimino), 16α-(benzimidazol-2-ylamino), and 16α-(benzothiazol-2-ylamino) steroid derivatives, were synthesized and tested against prostate cancer cell lines. Candidate compound 3f was shown to reduce AR-regulated transcription in a dose-dependent manner in nanomolar ranges and suppress expression of AR-regulated proteins Nkx3.

Two-step Synthesis of Solasodine Pivalate from Diosgenin Pivalate.

A two-step synthesis of solasodine pivalate from diosgenin pivalate is described. The key transformation involves the reaction of diosgenin pivalate with benzyl carbamate (CbzNH₂) promoted by TMSOTf. During the reaction the F-ring of the spiroketal moiety opens up with a simultaneous introduction of a Cbz-protected amino group in position 26.

Study on the reaction of diosgenin acetate with trimethylsilylazide catalyzed by Lewis acids.

The ring opening reaction of diosgenin acetate in presence of Lewis acids and trimethylsilyl azide was explored as a facile approach to the synthesis of an open chain derivative with a nitrogen-containing substituent at C26. The reaction, under optimal conditions (TMSOTf, 1 equiv.; TMSN, 1.

A study on the reaction of 16-dehydropregnenolone acetate with 2-aminobenzimidazole.

The condensation of 16-dehydropregnenolone acetate with 2-aminobenzimidazole was studied. The polycyclic aromatic product was formed as a single regioisomer in a cascade reaction comprising addition, cyclization, autoxidation, and aromatization, in addition to the rearranged D-homo product. The reaction mechanism based on DFT calculations is proposed.

Synthesis of Aromatic Retinoids and Curcuminoids and Evaluation of their Antiproliferative, Antiradical, and Anti-inflammatory Activities.

Natural retinoids and curcuminoids are known for their broad spectrum of biological properties, such as antioxidant, anti-inflammatory, antitumor, and so forth. In this work, a convenient synthesis of aromatic retinoids and curcuminoids from vinyl or allyl ketones, and the corresponding alcohols, using olefin metathesis as a key reaction, was elaborated. The best yields and diastereoselectivities were obtained from allylic or homoallylic alcohols by employing the two-step cross-metathesis/oxidation procedure.