Oksidacija holesta-5,8-dien-3β-il acetata sa perkiselinama

Expoxidation of cholesta-5,8-dien-3β-yl acetate (1) with peracids takes place preferentially at the more highly substituted Δ8-olefinic double bond to give: (a) with monoperphthalic acid, 8α,9α-epoxycholest-5-en-3β-yl acetate (2) (in 39 % yield) and 9α-hydroxy-5α,6α-epoxycholest-8(14)-en-3β-yl acetate (3) (in 30 % yield); and (b) with m-chloroperbenzoic acid, the 8α,9α-epoxide 2 (64 %) and 5α,6α-epoxy derivative 3 (20 %). Some chemical transformations of the obtained epoxides are described.Epoksidacija holesta-5,8-dien-3β-il acetata (1) sa perkiselinama prvenstveno se odvija na više supstituisanoj Δ8-olefinskoj dvoguboj vezi pri čemu se dobija: (a) sa monoperftalnom kiselinom, 8α,9α-epoksiholest-5-en-3β-il acetat (2) (u prenosu od 39 %) i 9α-hidroksi-5α,6α-epoksiholest-8(14)-en-3β-il acetat (3) (u prenosu od 30 %); i (b) sa m-hlorperbenzoevom kiselinom, 8α,9α-epoksid 2 (u prenosu od 64 %) i 5α,6α-epoksi derivat 3 (u prenosu od 20 %). Opisane su i neke hemijske transformacije dobijenih epoksida

Thionation of Some alpha,beta-Unsaturated Steroidal Ketones

The reactions of selected alpha,beta-unsaturated steroidal ketones with Lawesson's reagent (LR) in CH(2)Cl(2) and toluene under the standard reaction conditions and with a combination of phosphorus pentasulfide with hexamethyldisiloxane (P(4)S(10)/HMDO) in 1,2-dichlorobenzene (ODCB) under microwave irradiation were investigated and for this purpose several cholestane, androstane and pregnane carbonyl derivatives were chosen. Depending on the reagent and the solvent, 19 new sulfur containing compounds, including dithiones 4c and 4d, alpha,beta-unsaturated 3-thiones 3a-e, dimer-sulfides 2a-e, 1,2,4-trithiolanes 5a-e and phosphonotrithioates 6b-e were synthesized. All newly prepared compounds were characterized by IR, (1)H- and (13)C-NMR spectroscopy and elemental analysis

Kiselo-katalizovana i fotolitička reaktivnost nekih nezasićenih B-nor-5,10-sekosteroidnih ketona

The acid-catalyzed reaction of (Z)- and (E)-B-nor-5,10-seco-ketones 2 and 3 resulted in an intramolecular cyclization to give the 5-hydroxy-A-nor-1β,5β-10(19)-methylidene derivative 8, the 5β-hydroxy-A-nor-1(10)-unsaturated compound 9 and the 5β,10β-dihydroxy A-nor-product 10, from the (Z)-isomer and the 5-hydroxy-A-nor-1β,5β-10(19)-methylidene product 11, from the (E)-isomer. Upon UV-irradiation, the (Z)- and (E)-seco-ketones 2 and 3 underwent a reversible (Z)/(E) and (E)/(Z)-isomerization and in addition to a transannular photocyclization to afford the 10(19)-methylidene derivatives 8 and 11, respectively, while photolysis of the 10(19)-methylidene-B-nor-5,10-seco-ketone 4 gave the oxetane derivative 12.Kiselo-katalizovana reakcija (Z)- i (E)-B-nor-5,10-seko-ketona 2 i 3 rezultuje u intramolekulskoj ciklizaciji dajući 5-hidroksi-A-nor-1β,5β-10(19)-metilidenski derivat 8, 5β-hidroksi A-nor-1(10)-nezasićeno jedinjenje 9 i 5β,10β-dihidroksi-A-nor-proizvod 10, iz Z-izomera, i 5-hidroksi-A-nor-1β,5β-10(19)-metilidenski proizvod 11, iz E-izomera. (Z)- i (E)-Seko- ketoni 2 i 3 UV-ozračivanjem podležu reverzibilnoj (Z)/(E) odnosno (E)/(Z) izomerizaciji, kao i transanularnoj fotociklizaciji dajući 10(19)-metilidenske derivate 8 odnosno 11, dok se fotolizom 10(19)-metilidenskog-5,10-seko-ketona 4 gradi oksetanski derivat 12

Stereochemically Controlled Acetalizations in the Ten-Membered Ring of (Z)- and (E)-5,10-Seco-Steroidal Ketones

(Z)-3~-Acetoxy-5,10-seco-cholest-l(10)-en-5-one2a reacts with m-chloroperbenzoic acid to give the cis-(lS,10R)-epoxide 4, which, under acid-catalyzed conditions, undergoes stereospecific intramolecular cyclization to afford the (lS,5S,10S)-acetal 5. On the other hand, hydrolysis of the osmate ester of (E)-3~-acetoxy- -5,10-seco-cholest-1(10)-en-5-one 3a (with aqueous hydrochloric acid in methanol solution) produces two stereochemically different acetal derivatives, i. e. the (1R,5R,10R)-product7 and (1S,5S,10S)- -isomer 5, in ca. 49% and 28°/1 yields, respectively. The stereochemical course of these transformations is discussed in terms of the most stable ground-state conformations of the starting (Z)- and (E)-seco-ketones (2a and 3a) in solution

Synthesis of 5-azaandrostane-3β,17β-diol protected at the 17β-hydroxyl group

In the present paper, the preparation of 3β-hydroxy-17β-dimethyl- tert-butylsilyloxy-5-azaandrostane (15) in fourteen steps is described. B-nor-17-oxoandrost-5-en-3β-yl acetate (1) 1,2 was used as the starting material, which was transformed to the key intermediate of the synthesis, B-nor-17β-dimethyl-tert-butylsilyloxyandrost-4-en-3β-yl acetate (7)

Fotohemijsko i Bekmanovo premeštanje(z)-holest-4-en-6-on oksima

Beckmann rearrangement of (Z)-cholest-4-en-6-one oxime (4) (prepared in 4 steps starting from cholest-5-en-3β-ol ο1)) with thionyl chloride in dioxane solution afforded an enamide-type lactam, i.e. 7-aza-B-homocholest-4-en-6-one (6) as a single product. Photoreaction of the same compound in methanol or benzene-acetic acid solution gave a mixture of products, with the formation of the parent ketone 3 and the occurrence of Z/E isomerization, while the lactam 6 was obtained only when the reaction was performed in methanol and then in very low yield (7%).Bekmanovo premeštanje (Z)-holest-4-en-6-on oksima (4) (koji je dobijen u 4 faze, polazeći od holest-5-en-3 β-ola (1)) sa tionil-hloridom u dioksanskom rastvoru, kao jedini proizvod daje laktam enamidnog tipa, tj. 7-aza-B-homoholest-4-en-6-on (6). Fotoreakcijom istog jedinjenja u metanolu ili u rastvoru benzen-sirćetna kiselina, nastaje smesa proizvoda koju čine polazni keton 3 i proizvodi Z/E izomerizacije, dok je laktam 6 dobiven u vrlo niskom prinosu (7%) samo u metanolnom rastvoru

An improved approach to B-norsteroids: An one-pot preparation of 3β-acetoxy-5-oxo-5,6-seco-cholestan-6-oic and 3β-acetoxy-5,17-dioxo-5,6-seco-androstan-6-oic acids

A simple one-put procedure for the synthesis of the 5,6-seco-steroidal acids 9a,b in described in this paper. It consists of the epoxidation of the ▲ 5 -steroids, i.e., cholesteryl acetate (8a) and 17-oxo-aandrost-5-en-3β-yl acetate (8b) with peracetic acid (generated in situ by the H 2 WO 4 H 2 O 2 system), followed by the CrO 3 /H 2 SO_ oxidation of the thus formed epoxides. The 5,6-seco-steroidal acids 9a,b (obtained in about 90% and 77% yield, respectively) are transformed to the corresponding B-norsteroids by the known method (Beayer-Villiger oxidation and subsequent thermolysis of the respective β-lactones)

Cyclisation of alkoxy radicals. A semiempirical MNDO-PM3 study

The reactivity of the butoxy and 3-methylcyclohexyl radicals, as representatives of alkoxy radicals, was studied by MNDO-PM3 semiempirical MO method. In both cases it was found that the oxy radical underwent easily 1,5-H migration giving a δ-hydroxyalkyl radical. The hydrogen abstraction reaction goes through two transition states. The first transition state (TS) with short O-H distance has an energy very similar to, or lower than, the TS for 1,5-H migration. The second TS is of higher energy and is much product-like. The overall cyclisation reaction has a high activation energy (over 40 kcal mol-1), and is therefore unlikely to occur spontaneously. Most likely, the cyclisation step needs assistance of some other surrounding molecules to speed up the reaction

Cyclisation of alkoxy radicals. A semiempirical MNDO-PM3 study

The reactivity of the butoxy and 3-methylcyclohexyl radicals, as representatives of alkoxy radicals, was studied by MNDO-PM3 semiempirical MO method. In both cases it was found that the oxy radical underwent easily 1,5-H migration giving a δ-hydroxyalkyl radical. The hydrogen abstraction reaction goes through two transition states. The first transition state (TS) with short O-H distance has an energy very similar to, or lower than, the TS for 1,5-H migration. The second TS is of higher energy and is much product-like. The overall cyclisation reaction has a high activation energy (over 40 kcal mol-1), and is therefore unlikely to occur spontaneously. Most likely, the cyclisation step needs assistance of some other surrounding molecules to speed up the reaction

Antiproliferative activity of aroylacrylic acids. Structure-activity study based on molecular interaction fields

Antiproliferative activity of 27 phenyl-substituted 4-aryl-4-oxo-2-butenoic acids (aroylacrylic acids) toward Human cervix carcinoma (HeLa), Human chronic myelogenous leukemia (K562) and Human colon tumor (LS174) cell lines in vitro are reported. Compounds are active toward all examined cell lines. The most active compounds bear two or three branched alkyl or cycloalkyl substituents on phenyl moiety having potencies in low micromolar ranges. One of most potent derivatives arrests the cell cycle at S phase in HeLa cells. The 3D QSAR study, using molecular interaction fields (MIF) and derived alignment independent descriptors (GRIND-2), rationalize the structural characteristics correlated with potency of compounds. Covalent chemistry, most possibly involved in the mode of action of reported compounds, was quantitatively accounted using frontier molecular orbitals. Pharmacophoric pattern of most potent compounds are used as a template for virtual screening, to find similar ones in database of compounds screened against DTP-NCI 60 tumor cell lines. Potency of obtained hits is well predicted. © 2011 Elsevier Masson SAS. All rights reserved