M. L. Sá e Melo

Copper-catalysed allylic oxidation of Δ5-steroids by t-butyl hydroperoxide

Abstract Δ 5 -7-Oxosteroids are efficiently prepared from Δ 5 -steroids with t -BuOOH and a copper catalyst, either Cu(II) and Cu (I) salts or Cu metal; selectivity in the presence of a secondary alcohol is observed.

Oxidations with potassium permanganate — metal sulphates and nitrates. β-Selective epoxidation of Δ5-unsaturated steroids

Abstract The β-epoxidation of 3 β -acetoxy-Δ 5 -unsaturated steroids has been achieved with mmerous potassium permanganate-metal sulphates and nitrates with a high degree of stereoselectivity. 5β,6β-Epoxides are formed in a one step reaction in good yields and using very low cost reagents. The best results were achieved with KMnO 4 /Fe 2 (SO 4 ) 3 .nH 2 O.

A novel oxidation of homoallylic alcohols under sonochemical conditions

Abstract The oxidation of 3β-hydroxy-Δ 5 -cholestenes, -pregnenes and -androstenes to the corresponding Δ4-3,6-diones has been achieved in high yields by a new one-step process, using tetra- n -propylammonium perruthenate with 4-methylmorpholine N-oxide as co-oxidant, under sonochemical conditions.

Sonochemical reduction of α, β-epoxy ketones and α′-oxygenated analogs by aluminium amalgam

Abstract The sonochemical reductive opening of α, β-epoxy ketones and their α′-oxygenated (-OH or -OAc) analogs by aluminium amalgam allows shorter reaction times, better yields of the respective β-hydroxy ketones and minimization of by-products. The rates of these reactions are affected by the intensity of the acoustic waves and by temperature.

Ultrasound assisted zinc reactions in synthesis 1. Efficient reduction of enones

Abstract Zinc reduction of α, β-unsaturated ketones in acetic acid has been efficiently accomplished under sonochemical conditions. Different α-enone systems give two kinds of products: olefins and allylic alcohols. Regio- and stereoselective are reported.

Ultrasound assisted zinc reactions in synthesis 2. A new clemmensen-type reduction

Abstract A mild and efficient method is described for the reduction of carbonyls to methylene groups. Under ultrasonic irradiation, deoxygenation of 3-oxosteroids with zinc dust in acetic acid or acetic acid/water was achieved in 15 minutes. The observed selectivity at C-3 in the presence of 17- and 20-oxo groups is discussed.

3β,5α,6β-Trihy­droxy­androstan-17-one

The title compound, C19H30O4, is an androstan-17-one derivative synthesized from the dehydroepiandrosterone through a sequential addition of an oxidant, followed by a trans-diaxial opening of the epoxide generated, with Bi(OTf)3 (OTf is trifluoromethanesulfonate). The six-membered rings have a slightly flattened chair conformation, while the five-membered ring adopts a 14-α envelope conformation. All rings are trans fused. In the crystal, the molecules are connected by O—H⋯O hydrogen bonds involving the hydroxyl and carbonyl groups, forming a three-dimensional network. A quantum mechanical ab initio Roothan Hartree–Fock calculation of the free molecule gives bond lengths, valency angles and ring torsion angles of the free molecule at equilibrium geometry (energy minimum) close to the experimental values.

3α,4β-Dihydroxy-5α-androstan-17-one

The crystal structure of the title compound, C 19 H 30 O 3 , is reported. This steroid was obtained as an intermediate in the synthesis of formestane. The molecules are held together by a network of hydrogen bonds involving the carbonyl and hydroxyl groups.

Androstane-3β,5α,6β,17β-tetrol tri-hydrate.

The title hydrated tetrol, C19H32O4·3H2O, was synthesized by stereoselective reduction of the compound 3β,5α,6β-trihydroxyandrostan-17-one. All rings are fused trans. The organic molecules are connected head-to-tail along the c axis via O—H⋯O hydrogen bonds. Layers of water molecules in the ab plane interconnect these chains. A quantum chemical ab initio Roothan Hartree–Fock calculation of the isolated molecule gives values for the molecular geometry close to experimentally determined ones, apart from the C—O bond lengths, whose calculated values are significantly smaller than the measured ones, probably a consequence of the involvement of the C—OH groups in the hydrogen-bonding network.

6-[(4-Fluorophenyl)(1H-imidazol-1-yl)methyl]-1,3-benzodioxol-5-ol and 6-[(4-methoxyphenyl)(1H-imidazol-1-yl)methyl]-1,3-benzodioxol-5-ol.

The title compounds, C(17)H(13)FN(2)O(3) and C(18)H(16)N(2)O(4), are new potent aromatase inhibitors combining the common features of second- and third-generation nonsteroid anti-aromatase compounds. The molecules have a propeller shape, with dihedral angles between adjacent planes in the range 49-86°. A quantum mechanical ab initio Roothaan-Hartree-Fock calculation for the isolated molecules shows values for these angles close to the ideal value of 90°. Docking studies of the molecules in the aromatase substrate show that their strong inhibitor potency can be attributed to molecular flexibility, hydrophobic interactions, heme Fe coordination and hydrogen bonding.