2284-36-8Relevant academic research and scientific papers
BROMOFLUORINATION OF DOUBLE BONDS USING N-BROMOIMIDES AND TETRA-n-BUTYLAMMONIUM FLUORIDE AS A SOURCE OF FLUORIDE
Maeda, Minoru,Abe, Masayuki,Kojima, Masaharu
, p. 337 - 346 (1987)
Bromofluorination of 4-tert-butyl-1-methylcyclohexene (I) using a combination of N-bromosuccinimide and tetra-n-butylammonium fluoride as a source of fluoride gave the vicinal bromofluorides in acceptable yield.Similar treatment of methyl 3α,7α-diacetoxy-5β-chol-11-ene-24-carboxylate (IV) afforded the 12α-bromo-11β-fluoro steroid (V) in good yield.
Chemical Synthesis of Rare Natural Bile Acids: 11α-Hydroxy Derivatives of Lithocholic and Chenodeoxycholic Acids
Namegawa, Kazunari,Iida, Kyoko,Omura, Kaoru,Ogawa, Shoujiro,Hofmann, Alan F.,Iida, Takashi
, p. 403 - 411 (2018/06/08)
A method for the preparation of 11α-hydroxy derivatives of lithocholic and chenodeoxycholic acids, recently discovered to be natural bile acids, is described. The principal reactions involved were (1) elimination of the 12α-mesyloxy group of the methyl esters of 3α-acetate-12α-mesylate and 3α,7α-diacetate-12α-mesylate derivatives of deoxycholic acid and cholic acid with potassium acetate/hexamethylphosphoramide; (2) simultaneous reduction/hydrolysis of the resulting △11-3α-acetoxy and △11-3α,7α-diacetoxy methyl esters with lithium aluminum hydride; (3) stereoselective 11α-hydroxylation of the △11-3α,24-diol and △11-3α,7α,24-triol intermediates with B2H6/tetrahydrofuran (THF); and (4) selective oxidation at C-24 of the resulting 3α,11α,24-triol and 3α,7α,11α,24-tetrol to the corresponding C-24 carboxylic acids with NaClO2 catalyzed by 2,2,6,6-tetramethylpiperidine 1-oxyl free radical (TEMPO) and NaClO. In summary, 3α,11α-dihydroxy-5β-cholan-24-oic acid and 3α,7α,11α-trihydroxy-5β-cholan-24-oic acid have been synthesized and their nuclear magnetic resonance (NMR) spectra characterized. These compounds are now available as reference standards to be used in biliary bile acid analysis.
New synthesis of pentacyclic steroids by stereoselective epoxide ring opening
Ibrahim-Ouali, Malika,Khalil, Hamze
scheme or table, p. 6948 - 6950 (2011/03/18)
A stereoselective synthesis of pentacyclic steroids has been achieved. Starting from commercially available cholic acid 1, followed by asymmetric epoxidation and by stereoselective epoxide ring opening, employing nucleophilic species, the corresponding products were afforded in good yields. The compounds were being evaluated for their biological activity.
Introducing Δ11 unsaturation into steroid compounds
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, (2008/06/13)
A process for the introduction of Δ11 unsaturation into steroid compounds having a C-12 sulfonate ester group is described. Dehydrosulfonation is carried out by reacting the sulfonate with a hexaalkylphosphoric triamide. The process is particularly useful with steroid compounds that also contain a blocked C-7 hydroxy group. The process yields the 11-enate in preference to the 6,11-dienate. The yield of the process can be increased by carrying out the reaction in the presence of a weak base.
