6a,7a-epoxide

In the estrone series diaxial cleavage of the 6a,7a-epoxide (10) with methylmagnesium bromide affords (11) in 60% yield. ... 

Cleavage of 5a,6a- and 6a,7a- epoxides with azide ion and subsequent reduction with hydrazine has led to the preparation of 6 -amino-steroids, although similar treatment of 16a,17a-epoxypregnenolone acetate was accompanied by D-homoannulation to give, after reduction, the 16j3-amino-Ha-ketone. Azide displacement (lithium azide in DMF) of 3a,20j8-diacetoxy-... 

The formation of 5a-hydroxy-6 , 7 -epoxides can be explained, from 56,6B-epoxides as given in the scheme. This was explained from the following reason. 4-Deoxy-5B,6B-epoxides are less in number. Transdiaxial opening of epoxide forms glycol at C-5 and C-6 position. Dehydration at C-6 followed by epoxidation from the rear side produces 5o-hydroxy-6a,7a-epoxides. 

Electrophilic Addition.—The hydroxylation of alkenes, including several steroids, with osmium tetroxide has been reviewed. Addition of HOBr to the 19-functionalized-5a-cholest-6-enes (13) gave mixtures of the corresponding bromohydrins (14) and the 6,19-epoxides (15) whereas the analogous B-homo-compounds (16) gave only the 6,19-epoxides (17). Similar effects were noted for the related HBr- and HC104-catalysed opening of the 6a,7a-epoxides and it was observed that the predominant attack by the 19-0 atom [5(0)" attack] in the B-homo-series lay in the possibility of its linear approach with the C-6—Br or C-6—O bond. The reactions of chromyl chloride and chromyl fluoride with steroidal alkenes and dienes have been reported " and it was observed that the... 

The diaxial trans-g yco structure in a-muricholic acid was substantiated by partial synthesis. a-Muricholic acid could be derived from either the 6a, 7a-epoxide XVI [Hsia et al. (39)] or the 6,9,7/9-epoxide XV [Hsia et al. (41)] (Fig. 4) by scission of the epoxide rings and hydrolysis of the acetates thus formed. In accordance to the Fiirst and Plattner rule [Fiirst and Plattner (42)], ionic opening of an ethylene oxide results in the diaxial trans-g yco. The structure of a-muricholic acid therefore should be 3a,6,9,7a-tri-hydroxy-5/9-cholanic acid (XVII). The orientation of the epoxide ring in XV and that... 

Methanolysis of 17 -acetoxy-4)3,5 6a,7a-diepoxyandrostane catalysed by tetra-cyanoethylene yields 17j8-acetoxy-4a,7a-oxido-5 -hydroxy-6)3-methoxyandrostane. The methanolysis product of the 6a,7a-epoxide has participated in the cleavage of the 4j8,5 -epoxide. 

The remaining solution was diluted with DCM (2 ml), and m-chloroperbenzoic acid (mCPBA) (0.30 g, 2.0 mmol) was added portionwise. After stirring at RT for 40 h, the mixture was extracted with DCM and washed successively with aqueous sodium sulfite solution, aqueous sodium bicarbonate solution and water, dried (MgS04) and evaporated in vacuum. Column chromatography (45-70% ether-petrol, gradient elution) of the residue afforded the title epoxides (3aa,6a,7a,7aa)-6,7-epoxy-3a,6,7,7a-tetrahydrobenzo[d]-l,3-dioxol-2-one (73 mg, 47%) mp 87°-89°C and (3aa,6p,7p,7aa)-6,7-epoxy-3a,6,7,7a-... 

Tetrafluoroboric acid-diethyl ether complex (catalytic amount) was added to a stirred solution of epoxide (+/-)-(3aa,6a,7a,7aa)-6,7-epoxy-3a,6,7,7a-tetrahydrobenzo[d]-l,3-dioxol-2-one (32 mg, 0.2 mmol) and (R)-(+)-sec-phenethyl alcohol (0.048 ml, 0.4 mmol) in DCM at RT under argon. After 30 min, water was added and the mixture extracted with DCM (3 times). The combined organic phase was dried (MgS04) and evaporated in vacuum. Column chromatography (30-75% ether-petrol, gradient elution) of the residue afforded the alcohols [3aR-[3aa,4a,5p(R),7aa]-3a,4,5,7a-tetrahydro-4-hydroxy-5-(l-phenylethoxy)benzo[d]-l,3-dioxol-2-one and [3aS-[3aa,4a,5P(R),7aa]-3a,4,5,7a-tetrahydro-4-hydroxy-5-(l-phenylethoxy)benzo[d]-l,3-dioxol-2-one. (37 mg, 67%) as a thick oil and a 1 1 mixture of diastereomers. Subsequent HIPLC (l -Dynamax 83,123-6 column 6% isopropanol-petrol, 15 ml/min) effected separation of the diastereomers. Less polar [3aR-[3aa,4a,5p(R),7aa]-3a,4,5,7a-tetrahydro-4-hydroxy-5-(l-phenylethoxy)benzo[d]-l,3-dioxol-2-one had retention time 16.3 min [a]D2° +90.1° (c 1.1, CHCI3). 

Chromous acetate, known to reduce 16a,17a-epoxypregnan-20-ones to give 16a-hydroxypregnan-20-ones. has now been employed for similar reductions of 4a.5a- and 4/3,5)S-epoxy-3-ketones (114), and also of a 6a,7a-epoxy-4-en-3-one (115). In each case the epoxide was selectively reduced at the bond nearest the carbonyl group, giving the 5a- or 5/3-hydroxy-3-ketone (116), and the 7a-hydroxy-4-en-3-one (117), respectively, in yields of about 50%. A neutral or buffered solution is required to minimize elimination, which occurs when acidic chromous chloride is used. 

Synonyms AI3-17251 BRN 0091397 CCRIS 276 Caswell No. 423 Compound 269 ED EINECS 200-775-7 EN 57 Endrex Endricol Endrine ENT 17251 EPA pesticide chemical code 041601 Experimental insecticide 269 Hexachloroepoxyoctahydro-e/ r/o,e/ r/o-dimethanonaphtha-lene l,2,3,4,10,10-Hexachloro-6,7-epoxy-l,4,4a,5,6,7,8,8a-octahydro-enr/o,e/ c/o-l,4 5,8-dimeth-anonaphthalene 3,4,5,6,9,9-Hexachloro-la,2,2a,3,6,6a,7,7a-octahydro-2,7 3,6-dimethano-naphth[2,3-A]oxirene Hexadrin Isodrin epoxide Mendrin NA 2761 NCI-C00157 Nendrin NSC 8935 Octanex QMS 197 RCRA waste number D013 RCRA waste number P051 Stardrin Stardrin 20 UN 2761. 

Synonyms AI3-25584 EINECS 213-831-0 ENT 25584 Epoxy heptachlor HCE HE (3-Heptachlor epoxide Heptachloro epoxide l,4,5,6,7,8,8-Heptachloro-2,3-epoxy-2,3,3a,4JJa-hexahydro-4,7-methanoindene l,2,3,4,5,6,7,8,8-Heptachloro-2,3-epoxy-3a,4,7,7a-tetrahydro-4,7-methanoindene 5a,6,6a-Hexahydro-2,5-methano-2/f-indeno[l,2-A]oxirene 2,3,4,5,6,7,7 Hep tachloro-la,lb,5,5a,6,6a-hexahydro-2,5-methano-2//-oxireno[a]indene UN 2761 Velsicol 53-CS-17. 

The proportions of a- and /8-epoxides obtained by peracid reactions of cholest-4-ene and its 7a- and 7/3-hydroxy-, 7/8-acetoxy-, and 7-oxo-derivatives have been compared with data for similar 3-substituted cholest-5-enes. The derived 4a,5a-and 5a,6a-epoxides all reacted smoothly with sodium azide to give azido-alcohols, with maximum reaction rates when a hydroxy-group was suitably placed to provide... 

Cholestane-2a,3 -diot dibenzoate, 1008 aiolestane-2/3,3a-diol dibenzoate, 1008 Cholestane-3/S,7,S-diol 3,7-dicathylate, 366 Cholestane-3/3,4(5-diol 5a,6a-epoxide, 796 Cholestane-3d,7a-diol 3-monocathylate, 366 Cholestane-4a,5a-diol-3-one, 476 Cholestane-4/3,5/3-diol-3-one, 476 Cholestane-4a,5ii-diol 4-tosylate, 103, 104 Cholestane-5a,6a-diol 6-tosylate, 103,104 Cholestane-2,3-dione, 304, 962 enols of, 747... 

In 1963, cholesterol hydroperoxides were reported (36) in egg-containing foods irradiated by sunlight. Chicoye et al. (37) observed the following 5 photoxidation derivatives of cholesterol in spray-dried yolk exposed to either 40-watt fluorescent lamp (approx. 280 hours) or summer sunlight (5 hours) 33"hydroxy-cholest-5-en-7-one (7-keto) cholest-5-ene-33,7a-diol (7a-diol) cholest-5-ene-33,73-diol (73-diol) 5,63-epoxy-5a-cholestan-33-ol (3-epoxide) and 5a-cholestane-33, 5cx, 63-triol (triol). Subsequently, Tsai et al. (38) developed methodology to demonstrate the presence of 5,6a-epoxy-5a-cholestan-33-ol (a-epoxide) in dried egg products which were spiked with the epoxides. 

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