6997-41-7

To develop new potential pesticide candidates from low value-added natural bioactive products, a series of new cholesterol–matrine conjugates (I(a–e)–IV(a–e)) were prepared from two lead compounds cholesterol and matrine. Against Mythimna separata Walker, compound IVa exhibited 3.0 and 2.6 folds promising insecticidal activity of cholesterol and matrine, respectively; against Aphis citricola Van der Goot, compound IVd showed 4.3 and 2.2 folds potent aphicidal activity of their precursors; notably, it also showed good control effects in the greenhouse; against Plutella xylostella Linnaeus at a dose of 20 μg/nymph, compound IIIe exhibited 2.8 and 2.0 folds oral toxicity of cholesterol and matrine, respectively. Compounds IIIe, IVd and IVe can be used as the leads for further structural optimization as the insecticidal and aphicidal agents.

To explore natural-product-based pesticidal candidates and high value-added application of cholesterol in agriculture, oximinoether derivatives of cholesterol-containing isoxazoline/isoxazole fragments (I-1～I-16 and II-1～II-18) were semiprepared by structural optimization of cholesterol. Their structures were characterized by optical rotation, high-resolution mass spectrometry (HRMS), IR, and 1H NMR spectroscopy. Particularly, the Z configurations of oxime fragments at the C-7 position of target compounds were undoubtedly determined by X-ray crystallography. Against Mythimna separata Walker, compounds 3e, I-8, I-14, and II-3 showed 2.4-2.7-fold growth inhibitory activity of the precursor cholesterol. Against Plutella xylostella Linnaeus, compounds I-6, I-7, and I-9 showed 2.4-2.7-fold oral toxicity of cholesterol. Against Aphis citricola Van der Goot, compounds 2e and II-15 exhibited 4.9 and 5.8-fold aphicidal activity of cholesterol, respectively. Notably, they showed good control effects (3.0-5.0-fold promising control efficiency of 1) against A. citricola in the greenhouse. Structure-activity relationships (SARs) suggested that the C-3 hydroxyl group and the C-7 position of cholesterol are two important modification sites. It will pave the way for future structural optimization and application of cholesterol derivatives as potential pesticidal agents in agriculture.

The invention discloses a preparation method of obeticholic acid and an intermediate thereof. The invention provides a preparation method of a compound V. The preparation method of the compound V comprises the following steps: carrying out hydroxyl protective reaction on a compound VI and a hydroxyl protective reagent to obtain the compound V. The preparation method is simple and convenient to operate, low in cost, gentle in condition, environmentally friendly and suitable for industrialization.

The invention discloses a preparation method of obeticholic acid and an intermediate thereof. The provided preparation method of the obeticholic acid comprises the following step: carrying out oxidizing reaction on a compound V and an oxidizing agent in an organic solvent to obtain a compound IV so as to obtain the final product. PG1 is a carboxyl protecting group, PG2 is a hydroxyl protecting group, and a component as shown in specification in the compound V and the compound IV independently shows that the ethidine is an E configuration, a Z configuration or a mixture of the E configuration and the Z configuration. The preparation method is simple and convenient to operate, low in cost, gentle in condition, environmentally friendly and suitable for industrialization.

A mild, efficient and organocatalytic allylic oxidation of steroids using a TBAI/TBHP protocol has been developed. A range of bioactive Δ5-en-7-ones can be easily prepared from the corresponding Δ5-steroids. The methodology features several advantages, including readily available starting materials, environmentally benign oxidant, high functional group compatibility, and metal-free catalysis.

In the realm of aliphatic fluorination, the problem of reactivity has been very successfully addressed in recent years. In contrast, the associated problem of selectivity, that is, directing fluorination to specific sites in complex molecules, remains a great, fundamental challenge. In this report, we show that the enone functional group, upon photoexcitation, provides a solution. Based solely on orientation of the oxygen atom, site-selective photochemical fluorination is achieved on steroids and bioactive polycycles with up to 65 different sp3 C-H bonds. We have also found that γ-, β-, homoallylic, and allylic fluorination are all possible and predictable through the theoretical modes reported herein. Lastly, we present a preliminary mechanistic hypothesis characterized by intramolecular hydrogen atom transfer, radical fluorination, and ultimate restoration of the enone. In all, these results provide a leap forward in the design of selective fluorination of complex substrates that should be relevant to drug discovery, where fluorine plays a prominent role.

Abstract Readily available vanadyl acetylacetonate was found to oxidize the allylic sites of Δ5 steroidal alcohols without protection of hydroxyl groups. Cholesterol, dehydroepiandrosterone, cholesterol benzoate, cholesterol acetate, pregnenolone, and 5-pregnen-3,20-diene were oxidized to 7-keto products using vanadyl acetylacetonate in one pot reactions at room temperature in the presence of oxygen and water.

The invention relates to novel sterol derivatives, the preparation method thereof, pharmaceutical compositions containing them and use thereof for treating diseases involving transformed astrocyte cells or for treating malignant haemopathies. The inventio

Figure presented Tert-Butylperoxy radical was generated with PhI(OAc) 2 and tBuOOH. Ester solvent was found to be critical and the protocol was applied in the allylic oxidation of various olefinic substrates, which gave the corresponding α,β-unsaturated enones in good yield and regioselectivity.

A green and effective method is reported for the oxidation of cholesteryl acetate to 7-keto-cholesteryl acetate with O2 in the presence of catalytic amounts of N-hydroxyphthalimide (NHPI) under mild conditions. It was found that Co(OAc)2 could cooperate with Mn(OAc)2 to enhance the catalytic ability of NHPI resulting in better yields. This economical and environmentally-friendly method provides a potentially new way for the synthesis of the intermediate product of vitamin D3 in industry, which eliminates the use of large amounts of bromine in present route and overcomes the drawbacks of the known oxidation methods.

A new chromium(VI) reagent, 3,5-dimethylpyrazolium fluorochromate, C5H8N2H[CrO3F] (DmpzHFC), has been developed by reacting dmpz with CrO3 and aqueous HF for the selective oxidation of primary, secondary and allylic alcohols to the corresponding carbonyl compounds, polycyclic hydrocarbons to cyclic ketones and allylic Δ5-steroids to the corresponding α,β-unsaturated ketones.

Pyridinium fluorochromate (PFC), in refluxing benzene, has been found to be an effective and convenient reagent for the efficient oxidation of Δ5-steroids to the corresponding α,β-unsaturated ketones in high yields.

1-(tert-Butylperoxy)-1,2-benziodoxol-3(1H)-one (1a) oxidizes benzyl and allyl ethers to the esters at room temperature in benzene or cyclohexane in the presence of alkali metal carbonates. Since this reaction is compatible with other protecting groups such as MOM, THP, and TBDMS ethers, and acetoxy groups, and because esters are readily hydrolyzed under basic conditions, this new method provides a convenient and effective alternative to the usual reductive deprotection. Oxidation with 1a occurs readily with C-H bonds activated by both enthalpic effects (benzylic, allylic, and propargylic C-H bonds) and/or polar effects (α-oxy C-H bonds), generating α-oxy carbon-centered radicals, which can be detected by nitroxyl radical trapping. Measurement of the relative rates of oxidation for a series of ring-substituted benzyl n-butyl ethers 2d and 2p-s indicated that electron-releasing groups such as p-MeO and p-Me groups increase the rate of oxidation, and Hammett correlation of the relative rate factors with the σ+ constants of substituents afforded the reaction constant ρ+ = -0.30. The large value of the isotope effect obtained for the oxidation of benzyl n-butyl ether 2d (k(H)/k(D) = 12-14) indicates that the rate-determining step of the reactions probably involves a high degree of benzylic C-H bond breaking. The effects of molecular dioxygen were examined, and the mechanism involving the intermediacy of the tert-butylperoxy acetal 5 and/or the hydroperoxy acetal 32 is proposed. Particularly noteworthy is the finding that (tert-butylperoxy)iodane 1a can generate the tert-butylperoxy radical and the iodine-centered radical 33a, even at room temperature in solution, via homolytic bond cleavage of the hypervalent iodine(III)-peroxy bond.

The initial biosynthetic conversions of cholesterol to the bile acids involve sequential 7α-hydroxylation (catalyzed by cholesterol 7α-hydroxylase) followed by C-3 oxidation and concomittant double bond migration (to a Δ4-configuration, catalyzed by 3β-Δ5-C27-steroid oxidoreductase) to provide 7α-hydroxycholest-4-en-3-one.A straightforward, and economical, preparation (on a 0.1 g scale) of this pivotal biosynthetic intermediate has been devised.Reduction of 3β-(benzoyloxy)-cholest-5-en-7-one with LiB(sec-butyl)3H provided a 4:1 mixture, respectively, of the 7α- and 7β-hydroxy diastereomers, which were separated chromatographically.Solvolytic removal of the C-3 benzoyl group gave 3β,7α-cholest-5-ene-3,7-diol.A suspension of the 1:1 (v/v) complex (formed by mutual dissolution in MeOH, followed by evaporation of the solvent) of this diol with hydroxypropyl-β-cyclodextrin, at a concentration of 1 mg mL-1 (in neutral phosphate buffer), was converted by Brevibacterium sp cholesterol oxidase (0.25 U mg-1 of substrate) and catalase (70 U mg-1 of substrate, to recover O2 from the H2O2 produced by the enzymatic oxidation) to a suspension of 7α-hydroxycholest-4-en-3-one and the hydroxypropyl-β-cyclodextrin.The yield for the enzymatic conversion was in excess of 90percent.A much poorer and less reproducible yield ( 20percent) was seen in the absence of the hydroxypropyl-β-cyclodextrin.Routine extraction of this aqueous suspension, and chromatographic purification (85:15 CHCl3/acetone v/v on silica) of the residue, gave pure 7α-hydroxycholest-4-en-3-one in 68percent isolated yield.This route is a significant improvement, in terms of reaction scale and convenience, over the previous procedures for the preparation of this steroid. - Keywords: (7α)-hydroxycholesterol; hydroxypropyl-β-cyclodextrin; cholesterol oxidase; (7α)-hydroxycholest-4-en-3-one; bile acid biosynthesis; cholesterol 7α-hydroxylase

Pyridinium chlorochromate (PCC), in refluxing benzene, or dimethyl sulfoxide, and pyridinium dichromate (PDC) in pyridine, have been found to be effective reagents for the allylic oxidation of Δ5-steroids to yield the corresponding α,β - unsatu

The stereospecific syntheses of 7β- and 7α-hydroxycholesterols from cholesterol are described.

Alkenes were converted into α,β-unsaturated carbonyl compounds using excess of tert.butylhydroperoxide and catalytic amounts of chromiumVI oxide at room temperature.Fair yields and conversions were obtained from Δ5-steroids while allylic oxidation of acyclic alkenes was less efficient.Epoxidation of the double bond, sometimes observed, remained a minor reaction pathway.

Complexation of chromium trioxide with benzotriazole has been found to be an effective reagent for allylic oxidation.Pyridinium chlorochromate complexed with benzotriazole was found to selectively oxidize steroidal allylic alcohols in high yield.

2-Pyridineseleninic anhydride, prepared in situ by oxidation of the corresponding diselenide with iodoxybenzene, is an efficient reagent for the conversion of olefins to unsaturated ketones with retention of the original position of the double bond.This r

The desorption chemical ionization mass spectra, using ammonia as reagent gas, of several epimeric 3-hydroxysteroids and their ether and carboxylic acid ester derivatives are reported.In the case of steroids possessing a Δ4- or Δ5-3α-benzoate moiety, stereospecific stabilization of the protonated molecular ion + is observed.This behaviour is rationalized in terms of interaction of the double bond and the protonated benzoate group at C-3.Nucleophilic substitution by NH3 is observed when a double bond is present in the vicinity of the substitution center.The nature and the stereochemistry of the leaving group influence this substitution reaction.Our results seem to indicate the operation of a two-step mechanism (e.g.SN1 type reaction) rather than a SN2 type mechanism for the formation of the substitution ion +.