Enol Ethers of Steroid Ketones

Schwenk, Erw.; Fleischer, Gerhard; Whitman, B.

doi:10.1021/ja01274a506

Cited by 15 publications

(5 citation statements)

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“…As shown in Scheme 1, liquid acids and ion-exchange resins have been reported in the cyclic acetalization of 1,3-PD [11][12][13]. The catalytic efficiency of liquid acids is high.…”

Section: Introductionmentioning

confidence: 99%

Effective SO4 2−/TiO2–ZrO2 for preparation and hydrolysis of 1,3-propanediol acetals

Yang³

et al. 2010

Reac Kinet Mech Cat

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SO 4 2-/TiO 2 -M x O y (M = Zr, Ce, La) were prepared by the precipitation-impregnation method and characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), and temperature-programmed desorption (NH 3 -TPD). Catalytic activities were evaluated in the acetalization of 1,3-propanediol (1,3-PD) with acetaldehyde and hydrolysis of 2-methyl-1,3-dioxane (2MD). SO 4 2-/ TiO 2 -ZrO 2 (STZ) exhibited the best catalytic activity both in the acetalization and hydrolysis. With the molar ratio of Zr 4? /Ti 4? = 1:4, the highest yields were 96.45% in 3 h and 93.68% of 2MD hydrolyzed in 18 h, in contrast to the yields lower than 60% by using other superacids. These results are consistent with the strongest acidity of the superacid containing Zr 4? among prepared superacids containing other cations.

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“…As shown in Scheme 1, liquid acids and ion-exchange resins have been reported in the cyclic acetalization of 1,3-PD [11][12][13]. The catalytic efficiency of liquid acids is high.…”

Section: Introductionmentioning

confidence: 99%

Effective SO4 2−/TiO2–ZrO2 for preparation and hydrolysis of 1,3-propanediol acetals

Yang³

et al. 2010

Reac Kinet Mech Cat

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“…In 1938 Serini and Koster (253) and Schwenk, Fleischer, and Whitman (251) reported that steroidal 4-ene-3-ones react with triethyl orthoformate under mild conditions to form steroidal 3-ethoxy-3,5-dienes.…”

Section: Conversion Of 3-keto-j 4 -Steroids To 3-alkoxy-j 3 > 5 -Stermentioning

confidence: 99%

Reactions of Ortho Esters Which Result in Carbon-Oxygen and Carbon-Halogen Bond Formation

1970

Carboxylic Ortho Acid Derivatives - Preparation and Synthetic Applications

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In this chapter are considered reactions of trialkyl orthocarboxylates and tetraalkyl orthocarbonates which result in the formation of new carbonoxygen or carbon-halogen bonds. In most of these reactions the ortho ester (or an alkoxycarbonium ion derived from it) functions as an alkylating agent.Many of these reactions are useful synthetic tools. These include formation and hydrolysis of cyclic ortho ester derivatives of diols and triols (which serve to protect the hydroxyl groups of the polyols, and provide means for their mild monoacylation), alkylation of phenols, enols and acids (to form ethers and esters), and conversion of carbonyl compounds to acetals and ketals. Other reactions, such as the alkylation of halogens by ortho esters, are of only limited synthetic utility, while still others, such as the acidcatalyzed hydrolyses of ortho esters, are of interest primarily because of the light they shed on the mechanisms of reactions of ortho esters with nucleophilic reagents.

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“…By far, the reactive extraction method was considered as an efficient method [5][6][7], which had already succeeded in the recovery of 1,2-propanediol from dilute solutions [8], since the reaction of 1,3-PD and aldehyde was an acid-catalyzed reaction [9]. Many catalysts such as ion-exchange resin, liquid acid, and solid super acid were applicable in this reaction [10,11]. Among them, the solid acid SO 4 2-/TiO 2 -M x O y was more noticeable due to its good stability, regeneration, and high activity at moderate temperature [12][13][14] compared with ion-exchange resin and protonic acids.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Zirconia Promoted Sulfated Titania System with High Catalytic Activity

Yang³

et al. 2010

Chem Eng & Technol

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SO 42-/TiO 2 -ZrO 2 (STZ) solid superacid catalysts were prepared using the coprecipitation-impregnation method and characterized by FT-IR, XRD, NH 3 -TPD, N 2 adsorption-desorption isotherms, and SEM. It was observed that the sulfur content and the specific surface area of STZ changes with the ZrO 2 content, and passes through a maximum at Zr/Ti = 1/4. The results indicate that the molar ratio of Zr/Ti and nonionic surfactant, PEG, were helpful for increasing the surface areas and stabilizing the sulfate species on the surfaces of the catalysts. The catalytic activity results were supported by the hydrolysis reaction rate of 2-methyl-1,3-dioxane (2MD) that was strongly dependent on the sulfur content in the zirconia promoted sulfated titania catalyst.

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Enol Ethers of Steroid Ketones

Cited by 15 publications

References 0 publications

Effective SO4 2−/TiO2–ZrO2 for preparation and hydrolysis of 1,3-propanediol acetals

Effective SO4 2−/TiO2–ZrO2 for preparation and hydrolysis of 1,3-propanediol acetals

Reactions of Ortho Esters Which Result in Carbon-Oxygen and Carbon-Halogen Bond Formation

Preparation of Zirconia Promoted Sulfated Titania System with High Catalytic Activity

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