Ruthenium-Catalyzed Oppenauer-Type Oxidation of 3β-Hydroxy Steroids. A Highly Efficient Entry into the Steroidal Hormones with 4-En-3-one Functionality

Abstract

Oxidation of 5-unsaturated 3beta-hydroxy steroids 1 to the corresponding 4-en-3-one derivatives 2 can be performed efficiently by acetone at reflux in the presence of a catalytic system consisting of either (PPh(3))(3)RuCl(2) (3) and K(2)CO(3) or [(C(4)Ph(4)COHOCC(4)Ph(4))(&mgr;-H)][(CO)(4)Ru(2)] (4). The reaction proceeds via a ruthenium-catalyzed dehydrogenation of 1 and subsequent hydrogen transfer to acetone with concomitant double bond migration.

Pincer and Diamine Ru and Os Diphosphane Complexes as Efficient Catalysts for the Dehydrogenation of Alcohols to Ketones

“…[22] Interestingly, the ruthenium and osmium derivatives 7 and 13 in the presence of KOtBu have proven to efficiently catalyze the dehydrogenation of sterols in tBuOH/toluene mixture at 145 8C (bath temperature; Table 5). The compound cholest-4-en-3-one is formed quantitatively in 20 h by heating cholest-5-en3b-ol (Table 5, entry 1) with 7 (0.8 mol %) and KOtBu (4 mol %), as inferred from 1 H and 13 C NMR analyses, thus showing that this reaction occurs with excellent selectivity without formation of side products.…”

Synthesis of 1‐Silabicyclo[4.4.0]dec‐5‐en‐4‐ones: A Model of the A and B Rings of 10‐Silatestosterone

“…A catalytic method with the dichlorotris(triphenylphosphane)ruthenium complex in the presence of potassium carbonate in acetone allowed the Oppenauer oxidation of various steroidic homoallylic alcohols with the hydroxy group in the equatorial position to α,β-ethylenic ketones. [35] No reaction was observed with 22a under these conditions. This lack of reactivity may be related to the axial position of the hydroxy group.…”

Diosgenone Synthesis, Anti-Malarial Activity and QSAR of Analogues of This Natural Product

“…Diosgenone hemisynthesis from diosgenin is a good alternative for obtaining this substance when establishing its effects in an infected-mouse model and determining its in vivo activity, absorption and toxicity. Preparing other derivatives and synthesizing other compounds involving only diosgenone A-and B-rings could yield new types of antimalarial substances, even though attempting to obtain diosgenone from diosgenin in a single step has failed so far [21]. In short, a type of steroidal saponin whose bioassays in an animal model have shown promissory activity against P. falciparum has been reported for the first time here, though its structure should most likely be optimized to achieve the best pharmacokinetic properties.…”

“…The pertinent literature contains very few publications regarding diosgenone synthesis; these have dealt with the Oppenauer reaction with aluminum alkoxides [20], or ruthenium complexes [21]. However, yields have been poor or absent.…”

“…The residue was purified by chromatography on a silica gel column (hexane/EtOAc/DCM, 9:1:1) yielding compound 20 as a white solid (620 mg, 96%): R f = 0.6 (hexane/EtOAc 4:1). (21). DMSO (0.2 mL, 2.8 mmol, 93 eq.)…”