Mesoporous materials type Ti-MCM-41 prepared by hydrothermal and ultrasound-assisted techniques were characterized by XRD, SEM, TEM, nitrogen physisorption, ammonia TPD, UV-vis and FT-IR. Both showed the MCM-41 characteristic structure. Hydrothermal treatment allowed obtaining a well ordered material and ultrasound procedure gave a better titanium distribution. Electronic microscopy images revealed Ti dispersion zones as well as the quantity of metal in the structure. The catalytic activity of these materials were tested by acetylation of aromatic and steroidal alcohols to afford the corresponding esters in good yields.

Por tratamiento hidrotérmico y por ultrasonido, se prepararon materiales tipo Ti-MCM-41 que fueron caracterizados por DRX, MEB, MET, fisisorción de nitrógeno, TDP de amoniaco y espectroscopias de IR y UV-vis. Ambos materiales mostraron ordenamiento característico de los materiales MCM-41. Se demostró que mediante la técnica de tratamiento hidrotérmico se obtuvo un material más ordenado pero, por la técnica de ultrasonido se logró mejor dispersión de titanio. Las imágenes de microscopía electrónica de barrido permitieron identificar las zonas de mejor distribución del Ti así como la cuantificación del metal en la estructura del MCM-41. La actividad catalítica de los materiales se probó en la acetilación de alcoholes aromáticos y esteroidales para obtener los ésteres correspondientes en buen rendimiento.

Uma rota conveniente para a síntese de 3beta-hidroxi-6-oxo-5alfa-esteroides a partir de delta5-esteroides é descrita tendo sido aplicada para a síntese da laxogenina, substância que apresenta atividade como hormônio de crescimento vegetal. O método é uma alternativa para instalar este grupo funcional importante encontrado em esteróides naturais. O processo descrito utiliza reagentes baratos e pode ser executado em quatro etapas. As etapas de oxidação e de tratamento ácido não afetam a cadeia lateral espirocetálica presente na diosgenina (16).

A convenient pathway to obtain 3beta-hydroxy-6-oxo-5alpha-steroids from 3beta-acetoxy delta5-steroids is reported; the methodology was applied to the synthesis of laxogenin (7), substance that behaves as a plant growth hormone. This is an alternative way to produce an important functionality found in many examples of naturally occurring steroids. The developed procedure uses inexpensive reagents and can be carried out in four steps. The oxidizing and acidic steps used in this methodology did not affect the labile spiroketal side chain present in diosgenin (16).

Uma rota conveniente para a síntese de 3β-hidroxi-6-oxo-5α-esteroides a partir de Δ5-esteroides é descrita tendo sido aplicada para a síntese da laxogenina, substância que apresenta atividade como hormônio de crescimento vegetal. O método é uma alternativa para instalar este grupo funcional importante encontrado em esteróides naturais. O processo descrito utiliza reagentes baratos e pode ser executado em quatro etapas. As etapas de oxidação e de tratamento ácido não afetam a cadeia lateral espirocetálica presente na diosgenina (16).

A convenient pathway to obtain 3β-hydroxy-6-oxo-5α-steroids from 3β-acetoxy Δ5-steroids is reported; the methodology was applied to the synthesis of laxogenin (7), substance that behaves as a plant growth hormone. This is an alternative way to produce an important functionality found in many examples of naturally occurring steroids. The developed procedure uses inexpensive reagents and can be carried out in four steps. The oxidizing and acidic steps used in this methodology did not affect the labile spiroketal side chain present in diosgenin (16).

The synthesis of two new spirostanic analogs of the natural occurring brassinosteroid 6-desoxocastasterone (1) is described. The scheme consists in the formation and elimination of tigogenin mesylate followed by catalytic dihydroxylation of the resulting D2-steroid (3) and acetylation of the 2a, 3a-diol introduced.Treatment diacetate (5) with NaNO2/BF3.Et2O and chromatography in alumina led to a 23-keto (6) which on reduction produced the 23S alcohol (8) as major product. Saponification of the 2a, 3a-diacetoxy-23-keto compound (6) and the 2a,3a-diacetoxy-23-hydroxy compound (8) led to the spirobrasinosteroids (7) and (9).13C NMR and ¹H RMN characteristics derived from substitution at C23 are briefly discussed.