1182-06-5Relevant articles and documents
Preparation method of 7-dehydrocholesterol for production of vitamin D3
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, (2021/04/07)
The invention particularly discloses a preparation method of 7-dehydrocholesterol for production of vitamin D3. The preparation method comprises the following steps: an esterification reaction, a bromination reaction, a debromination reaction and a saponification hydrolysis reaction. The esterification reaction comprises the following steps: adding cholesterol, an acid-binding agent and a solid catalyst into petroleum ether, carrying out heating to 45-50 DEG C in a nitrogen atmosphere, dropwise adding benzoyl chloride, performing heating to 78-82 DEG C after dropwise adding, conducting stirring for a reaction for 3-5 hours, adding distilled water to quench the reaction, performing filtering to obtain filter residues and a filtrate, extracting the filter residues with distilled water, concentrating an oil layer, then adding acetone, carrying out a reflux reaction for 30-40 minutes, conducting cooling to 20-30 DEG C, and performing filtering to obtain cholesterol benzoate; and soaking, filtering and drying the filter residues to obtain a solid desiccant, and repeatedly using the solid desiccant. The method has the advantage of facilitating cyclic utilization of the catalyst.
7 - Dehydrogenated cholesterol and preparation method thereof
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Paragraph 0103-0107; 0119-0122; 0143-0147, (2021/11/10)
7 - Dehydrogenated cholesterol and a preparation method thereof relate to the technical field of organic synthesis chemistry. A method for preparing 7 - dehydrogenated cholesterol, comprising performing a hydrazone reaction of 7 - arylsulfonyl hydrazone -3 - cholesterol ester to obtain an organic layer containing 7 - dehydrogenated cholesterol ester. The organic layer containing 7 - dehydrogenated cholesterol ester is subjected to saponification reaction to obtain 7 - dehydrogenated cholesterol. The hydrazone radical trapping agent is added in the hydrazone reaction process. The method can effectively inhibit the generation of aromatization impurities, wherein the total yield of the hydrazone saponification two-step reaction reaches 95% and 7 - dehydrogenated cholesterol is up to 97%.
KINETICS AND MECHANISM OF THE MONOMOLECULAR HETEROLYSIS OF INDUSTRIAL ORGANOHALOGEN COMPOUNDS. XIII. NATURE OF SALT EFFECTS IN THE DEHYDROBROMINATION OF 7α-BROMOCHOLESTEROL BENZOATE IN γ-BUTYROLACTONE, NITROBENZENE, AND o-XYLENE
Ponomarev, N. E.,Dvorko, G. F.
, p. 388 - 400 (2007/10/02)
By the verdazyl method we studied the influence of salts on the rate of heterolysis of 7α-bromocholesterol benzoate in γ-butyrolactone, nitrobenzene, and o-xylene, v = k.It was shown that the rate of the heterolysis of 7β-bromocholesterol benzoate in these solvents is higher than the rate of the heterolysis of the α epimer by factors of 7, 12, and 110 respectively.
Process for synthesis of 5α-cholest-8(14)-en-3β-ol-15-one and other 15-oxygenated sterols
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, (2008/06/13)
A process for preparing 15-oxygenated sterols, such as 3β-hydroxy-5α-cholest-8(14)-ene-15 one, comprising converting 7-dehydrocholesterol to 3β-benzoyloxycholesta-5,7-diene, converting the 3β-benzoyloxycholesta-5,7-diene to a 3β-benzoyloxy-5-cholesta-7,14-diene, converting the 3β-benzoyloxy-5-cholesta-7,14-diene to a 3β-benzoyloxy-14α, 15α-epoxy-5-cholest-7-ene and converting the 3β-benzoyloxy-14α, 15α-epoxy-5-cholest-7-ene to a 15-oxygenated sterol. Preferably, the 3β-benzoyloxy-cholesta-5,7-diene is converted to a 3β-benzoyloxy-5-cholesta-7,14-diene by (i) contacting 3β-benzoyloxy-cholesta-5,7-diene, in a solvent at a temperature of at most about -55° C., with HCl at a concentration of at least about 2.0 M for a time sufficient to convert the 3β-benzoyloxycholesta-5,7-diene to a 3β-benzoyloxy-5-cholesta-7,14-diene; (ii) neutralizing the resultant reaction mixture with a base to prevent formation of a significant amount of 3β-benzoyloxy-5-cholesta-8,14-diene; and (iii) recovering the 3β-benzoyloxy-5-cholesta-7,14-diene.
Brominating and oxidizing agent and method of using same
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, (2008/06/13)
There is provided a brominating and oxidizing agent of the formula: STR1 wherein R1, R2, R3 and R4 which may be the same or different, represents a member selected from the group consisting of a hydrogen atom, a C1 -C22 straight or branched alkyl group, a phenyl group, and a substituted phenyl group whose substituents are selected from the group consisting of a methoxy group, a nitro group, a cyano group, a halogen atom (Br, Cl, I), a C1 -C2 dialkylamino group, a C1 -C2 dialkylaminomethyl group, a C1 -C2 dialkylaminoethyl group, a C1 -C2 dialkylammoniummethyl group, a C1 -C2 dialkylammoniumethyl group, a C1 -C2 trialkylammoniummethyl group, a C1 -C2 trialkylammoniumethyl group, a COOR5 group, and a CON(R5)2 group, wherein R5 represents a C1 -C8 straight or branched alkyl group. The compounds falling within formula (I) find wide application as brominating and oxidizing agents in a number of organic reactions in which the prior art compound, N-bromosuccinimide has been employed to date. In comparison to N-bromosuccinimide, the compounds of the instant invention are characterized as being extremely stable to degradation and less polar with respect to their N-Br bond than N-bromosuccinimide such that promotion of "radical" bromine release is achieved with minimal positive bromine release.
