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Updated: Dec 31, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Palladium catalyzed synthesis of benzannulated steroid spiroketals
Martha C Mayorquín-Torres1, Juan Carlos González-Orozco2, Marcos Flores-Álamo1
1Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Ciudad de México, Mexico. martin.iglesias@unam.mx.
Abstract:
Nine cytotoxic [5/7] and [6/6] benzannulated steroid spiroketals were synthesized by palladium catalyzed spiroketalization of 5α and 5β-alkynediols derived from testosterone, diosgenin and cholesterol. The regioselectivity of the spiroketalization reaction is decisively influenced by the α or β-orientation of the hydroxyl group at C-5. NMR and single crystal X-ray diffraction corroborated the structure of the obtained compounds. Compounds bearing a cholestane skeleton exhibited higher cytotoxicity against U251 and T47D cells, and the BrdU incorporation assay suggests that the synthesized spiroketals inhibit cell proliferation.
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