1975-34-4Relevant academic research and scientific papers
The Crystal Structures of the α- and β-Diastereomers of 4,5-Epoxy-cholestan-3-one
Alarcón-Manjarrez, Carlos,Vargas-Romero, Katherine,González-Cruz, Thelma L.,Flores-álamo, Marcos,Iglesias-Arteaga, Martín A.
, p. 155 - 161 (2016)
The α and β-diastereomers of 4,5-epoxy-cholestan-3-one were obtained by epoxidation of cholest-4-en-3-one with H2O2 in basic media. The α-diastereomer 2a shows a monoclinic crystal system with dimension of cell unit: a = 11.6088(15), b = 6.3272(8), c = 16.164(2) ?; β = 94.040(11)° and trans A/B, B/C and C/D ring junctions and the β-diastereomer 2b has a orthorhombic crystal system with dimension of cell unit: a = 9.0542(4), b = 10.6737(5), c = 24.9723(9) ? and cis A/B, trans B/C and trans C/D rings junctions.
Synthesis of Symmetrical and Hybrid Dimeric Steroids by Double Suzuki-Miyaura Cross Coupling of 4-Bromo-3-oxo Steroids and Benzene-1,4-diboronic Acid
Flores-álamo, Marcos,Iglesias-Arteaga, Martín. A.,Mayorquín-Torres, Martha C.,Santiago-Sampedro, Gerardo I.
, p. 2909 - 2914 (2019)
Two symmetrical dimers and one hybrid dimer in which the steroid cores are connected by a 1,4-phenylene moiety were obtained by double Suzuki-Miyaura cross coupling of benzene-1,4-diboronic acid with 4-bromo-4-en-3-oxosteroids derived from cholesterol and diosgenin. Detailed NMR characterization of the obtained dimers is described.
1,3-Chirality transfer by fragmentation of allylsulfinic acids: A diastereoselective approach to vinyl bromides related to trans-hydrindane or trans-decalin
Chochrek, Pawel,Wicha, Jerzy
, p. 2534 - 2542 (2007)
Diastereoselective approaches to vinyl bromides from bromoallylic alcohols by fragmentation of the respective allylsulfinic acids have been investigated. Bromoallylic alcohols 1a and 6 were transformed into the respective 1,3-benzothiazol-2-yl sulfides 2a and 7 by the Mitsunobu inversion reaction under modified conditions. The sulfides were then oxidized into sulfones 11a and 12a, respectively. Reduction of 11a and 12a with sodium borohydride gave the respective allylsulfinic acid salts 13a and 15 which, without isolation, were treated with aqeous tartaric acid. The salt 13a gave exclusively 5α-cholestane derivative 14a whereas 15 provided a mixture of the 5α and 5β derivatives 16 and 17 (after deprotection), the former prevailing. In an alternative approach, benzothiazolyl sulfides 2a and 7 were treated sequentially with BH3·THF and LiAlH4 to give thiols 18a and 19a, respectively. Oxidation of thiols 18a and 19a with oxaziridine 21 gave the respective sulfinic acids which, on gentle heating, afforded bromoolefins 14a and 22a, respectively, as the only products. Analogous reaction sequences starting from allylic alcohols devoid of the bromine substituent 1b and 8 have also been studied. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Unambiguous assignment of 13C NMR signals in epimeric 4,5-epoxy-3-oxo-steroids assisted by X-ray diffraction and Gauge Invariant Atomic Orbitals calculation of absolute isotropic shieldings
Labra-Vazquez, Pablo,Galano, Annia,Romero-Avila, Margarita,Flores-Alamo, Marcos,Iglesias-Arteaga, Martin A.
, p. 107 - 125 (2013/09/12)
Complete assignments of the 13C signals of diastereomeric 4,5-epoxy-3-oxo steroids based on a combination of 1D and 2D NMR techniques are described The assignments were corroborated or corrected by calculation of the absolute isotropic 13C NMR shieldings using the Gauge Invariant Atomic Orbitals (GIAO) method at B3LYP/6-31+G(d,p) level. ARKAT-USA, Inc.
Highly efficient epoxidation of unsaturated steroids using magnesium bis(monoperoxyphthalate) hexahydrate
Carvalho, Jo?o F.S.,Silva, M. Manuel Cruz,Sá e Melo, M. Luisa
experimental part, p. 2773 - 2781 (2009/08/15)
Fast generation of epoxides from the corresponding homoallylic and allylic steroidal olefins was developed by using magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) as oxidant suspended in acetonitrile (CH3CN) at reflux temperature. The protocol involves the use of a safe readily available oxidant along with an easy work-up, which renders the process very efficient. Selective 4,5- and 5,6-epoxidations of steroids are reported. Among them, highly stereoselective epoxidation of Δ5-B-nor-cholestanes was achieved. Moreover, the method is chemoselective for the 5,6-position and can be applied to the epoxidation of ring-A enones.
Diastereoselective epoxidation of olefins by organo sulfonic peracids, II
Kluge,Schulz,Liebsch
, p. 2957 - 2976 (2007/10/03)
We have investigated the behaviour of sulfonic peracids 2 in situ generated towards olefins 7a, 7b, 9, 11, 14, 16, 18, allylic acid and homoallylic alcohols 20, 22, 24, 26, 28, 30, 33 and α,β-unsaturated ketones 35, 37, 39. Generally, the epoxidation proceeds in a peracid-like manner with greater diastereoselectivity than those by common oxidants. In particular, the epoxidation of Δ4 3-ketosteroids 39a-i led to 4α,5α-epoxides 40a-i with remarkable high de-values. Enhanced α-selectivity was also found in the epoxidation of cholesterol 28b. Due to the mild reaction conditions, even acid sensitive epoxides 8a, 8b, 10, 12, 13, 15, 17, 19 were obtained in good yields.
Isolation and Structure Elucidation of Seven New Polyhydroxylated Sulfated Sterols from the Ophiuroid Ophiolepis superba
D'Auria, M. Valeria,Riccio, Raffaele,Uriarte, Eugenio,Minale, Luigi,Tanaka, Junichi,Higa, Tatsuo
, p. 234 - 239 (2007/10/02)
Seven new polyhydroxylated sulfated sterols, all possessing 3α,21-disulfoxy-4α-hydroxy substituents and the A/B cis ring junction, have been isolated from the ophiuroid Ophiolepis superba, collected at Okinawa, Japan.Four sterols possessed identical nuclei (i.e., 3α-sulfoxy-4α-hydroxy) but differed in the side chain.Two possessed one more hydroxyl group in the nucleus located at C-2β, and one had the extra hydroxyl group at C-5β.Their general structure was deduced from spectral data (1H and 13C NMR and FABMS), and the stereochemistry of some of them was determined by correlating their respective spectral data with those of synthetic sterols.
A CONTRIBUTION TO PEROXY ACID OXIDATION OF α,β-UNSATURATED KETONES AND LINEARLY CONJUGATED DIENONES: REACTIONS IN THE CHOLESTANE SERIES
Cerny, Vaclav,Budesinsky, Milos,Ryba, Milos,Turecek, Frantisek
, p. 1549 - 1567 (2007/10/02)
Oxidation with 3-chloroperoxybenzoic acid of s-cis α,β-unsaturated ketones IX, XI and s-trans types X, XII was compared.The s-cis ketones show higher reactivity and furnish a higher yield of the corresponding α,β-epoxy ketones than the s-trans ketones.Products of the Baeyer-Villiger reaction are formed only in low yield.The dienone VI is oxidized predominantly to VII thus violating the rule that linear conjugated dienones are epoxidized at the double bond more distant from the carbonyl group; this result is in accord with the behaviour of s-cis α,β-unsaturated ketones. 1H NMR and 13C NMR data of the starting compounds and of the products are reported.
Peroxide oxidation of Δ4-3-ketosteroids
Holland, Herbert L.,Riemland, Elly,Ulrich, Daum
, p. 1919 - 1923 (2007/10/02)
Treatment of Δ4-3-ketosteroids with tert-butyl hydroperoxide in the presence of lithium hydroxide leads to the formation of the corresponding 4β,5β epoxides stereospecifically and in good yield.The stereospecificity of this reaction is explicable in terms of the accepted mechanism for the hydrogen peroxide epoxidation of Δ4-3-ketosteroids.The use of aqueous sodium peroxide as oxidant leads to the production of the corresponding Δ4-3,6-diones.A mechanism for this reaction is proposed in which the key step is autooxidation of the corresponding deconjugated Δ5-3-ketone, produced from the starting material in situ by the action of the reagents.Lithium peroxide does not oxidize androst-4-ene-3,17-dione at C-6, but produces the 4,5-epoxides in low yield together with an A-nor-3,5-secoacid.
