3090-70-8Relevant academic research and scientific papers
Steroid–Fullerene Hybrids from Epiandrosterone: Synthesis, Characterization and Theoretical Study
Almagro, Luis,Hernández-Castillo, David,Ortiz, Orlando,Alonso, Dayana,Ruiz, Alberto,Coro, Julieta,Herranz, María ángeles,Molero, Dolores,Martínez-álvarez, Roberto,Suárez, Margarita,Martín, Nazario
, p. 4512 - 4522 (2018/09/13)
New hybrid fullerene–steroid derivatives were prepared by using the Bingel–Hirsch protocol, by treatment of [60]fullerene with malonates bearing the appropriate steroid moieties obtained, in turn, from the functionalization of epiandrosterone, an important naturally occurring steroid hormone. Monocycloadduct C60-steroid conjugates were obtained by functionalization of ring A or ring D of the steroid moiety. We have also described the multistep preparation of a [60]fullerene hybrid dumbbell endowed with two fullerene units connected through an epiandrosterone molecule by a cyclopropanation reaction. The new compounds have been spectroscopically characterized and their redox potentials, determined by cyclic voltammetry, reveal three reversible reduction waves for monocycloadducts (8, 9 and 11, 12), whereas dumbbell-type derivative 10 exhibits the best electron-accepting abilities of the Bingel-type fullerene–steroid series. Theoretical calculations at semiempirical (AM1) and single point B3LYP-D3/6-31G+(d,p) levels have predicted the most stable conformations for the hybrid compounds and allow explaining the observed regioselectivity in the cyclopropanation reaction with dimalonate 7 during the synthesis of the dumbbell derivative.
Epimerization of Tertiary Carbon Centers via Reversible Radical Cleavage of Unactivated C(sp3)-H Bonds
Wang, Yaxin,Hu, Xiafei,Morales-Rivera, Cristian A.,Li, Guo-Xing,Huang, Xin,He, Gang,Liu, Peng,Chen, Gong
, p. 9678 - 9684 (2018/07/21)
Reversible cleavage of C(sp3)-H bonds can enable racemization or epimerization, offering a valuable tool to edit the stereochemistry of organic compounds. While epimerization reactions operating via cleavage of acidic C(sp3)-H bonds, such as the Cα-H of carbonyl compounds, have been widely used in organic synthesis and enzyme-catalyzed biosynthesis, epimerization of tertiary carbons bearing a nonacidic C(sp3)-H bond is much more challenging with few practical methods available. Herein, we report the first synthetically useful protocol for the epimerization of tertiary carbons via reversible radical cleavage of unactivated C(sp3)-H bonds with hypervalent iodine reagent benziodoxole azide and H2O under mild conditions. These reactions exhibit excellent reactivity and selectivity for unactivated 3° C-H bonds of various cycloalkanes and offer a powerful strategy for editing the stereochemical configurations of carbon scaffolds intractable to conventional methods. Mechanistic study suggests that the unique ability of N3? to serve as a catalytic H atom shuttle is critical to reversibly break and reform 3° C-H bonds with high efficiency and selectivity.
Silver-mediated oxidative aliphatic C-H trifluoromethylthiolation
Guo, Shuo,Zhang, Xiaofei,Tang, Pingping
, p. 4065 - 4069 (2015/03/30)
The first example of a practical and direct trifluoromethylthiolation reaction of unactivated aliphatic C-H bonds employs a silver-based reagent. The reaction is operationally simple, scalable, and proceeds under aqueous conditions in air. Furthermore, its broad scope and good functional-group compatibility were demonstrated by applying this method to the selective trifluoromethylthiolation of natural products and natural-product derivatives.
A new simple and high-yield synthesis of 5α-dihydrotestosterone (DHT), a potent androgen receptor agonist
Purushottamachar, Puranik,Njar, Vincent C.O.
, p. 1530 - 1534 (2013/01/15)
We have devised an efficient procedure for the synthesis of 5α-dihydrotestosterone (DHT) (1) starting from 3β-hydroxy-5α- androstan-17-one, providing the product in unprecedented 82% yield. A reported method of using toxic Jones reagent is replaced by milder oxidizing agent (NMO/TPAP) in the synthesis of a key intermediate 17β-[(tert- butyldimethylsilyl)oxy]-5α-androstan-3-one (18). This new procedure is simple, does not require special apparatus/precautions or chromatographic purification in most of the steps.
Synthesis of 5α-androstan-3β,17β-diol from tigogenin
Merlani,Amiranashvili,Men'Shova,Kemertelidze
, p. 97 - 99 (2008/02/13)
5α-Androstan-3β,17β-diol (3b-adiol), a known inhibitor of prostate cancer cell growth, was synthesized from tigogenin. Its structure was confirmed by NMR and IR spectroscopy and mass spectroscopy. Springer Science+Business Media, Inc. 2007.
Practical synthesis of androgen: The efficient transformation of 17-oxo group to 17α-hydroxy group
Ohta, Tetsuo,Zhang, Huyue,Torihara, Yoshitaka,Hida, Takemasa,Furukawa, Isao
, p. 630 - 632 (2007/10/03)
The present report describes the improved transformation of the 17-oxo group in 3β-acetoxy-5α-androstan-17-one to a 17α-hydroxy group. A mixture of 17α-acetoxy and 16-ene compounds, which are usually produced by the standard synthetic route, were treated with peracetic acid (epoxidation of the 16-ene compound) and then sodium borohydride-sodium hydroxide (reduction- hydrolysis) to give the desired 17α-hydroxy compound in much better yield than that in previous reports. Recrystallization of the crude product with cyclohexane-methanol gave the pure compound in 54% yield (total yield from starting ketone).
Regioselective esterification of polyhydroxylated steroids by Candida antarctica lipase B
Bertinotti, Anna,Carrea, Giacomo,Ottolina, Gianluca,Riva, Sergio
, p. 13165 - 13172 (2007/10/02)
The regioselectivity of Candida antarctica lipase B towards the acetylation of polyhydroxylated steroids has been systematically investigated. The enzyme showed a marked preference for the alcoholic moieties on the A ring and: on the steroidal side chain, making it possible the selective acylation at the positions 3 or 21 of polyhydroxy steroids. Acylation with the synthetically useful esters chloroacetate and levulinate was also accomplished, whereas esterification with benzoate and pivaloate was unsuccessful.
STEROIDS .LIII. TRANSFORMATION OF 3β-ACETOXY-5α-ANDROSTAN-17-ONE INTO 17α- AND 17β-AMINO DERIVATIVES OF 5α-ANDROSTAN-3β-OL
Nadaraia, N. Sh.,Sladkov, V. I.,Kuleshova, L. N.,Suvorov, N. N.
, p. 481 - 485 (2007/10/02)
The epimeric 17α- and 17β-amino-5α-androstan-3β-ols were synthesized from 3β-acetoxy-5α-androstan-17-one.The configurations at the C17 atom were demonstrated by the 1H NMR method.
Favorskii Rearrangements of α-Halogenated Acetylcycloalkanes. 4. Stereochemistry of Cyclopropanonic Rearrangements and the Influence of Steric Factors on the Competing Formation of α-Hydroxy Ketones
Engel, Ch. R.,Lachance, P.,Capitaine, J.,Zee, J.,Mukherjee, D.,Merand, Y.
, p. 1954 - 1966 (2007/10/02)
It is shown that the marked stereoselectivity, in favor of 17α-methylated etio acid derivatives, of Favorskii rearrangements in protic and polar media of 17-brominated 20-keto steroids - somewhat diminished by a bulky 12α-substituent, such as an acetoxy group - is due, to an appreciable extent, to the influence of the 18-methyl group.Thus, the rearrangement of 17-bromo-3β-acetoxy-18-nor-5α-pregnan-20-one, which was synthesized from 3β-acetoxy-5α-androstan-17-one, proceeds with potassium bicarbonate in aqueous methanol much less stereoselectively than analogous rearrang ements of 13-methylated 17-bromo 20-ketones, and in its reaction with potassium methoxide in absolute methanol the yield of the 17β-methyl 17α-etio ester even exceeds that of the 17α-methylated rearrangement product, in contradistinction to the results of equivalent reactions of 13-methylated substrates.It is also shown that in the absence of the 18-methyl group a 17β-hydroxy 20-ketonic substitution product and related adducts are obtained in high proportion, and it is concluded that the quasi-absence of such products in analogous reactions of 13-methylated 17-bromo 20-keto steroids is essentially due to the steric impediment exerted by this group to the formation of intermediate epoxy ethers.The results presented agree with the hypothesis of a competition between concerted and nonconcerted cyclopropanone formations from α-halo enolates, in part dependent on the polarity and protonicity of the medium, or possibly with that of gradients of mechanisms, and they support the intermediacy of epoxy ethers in the formation of α-hydroxy ketones as side products of Favorskii rearrangements.
A NEW POWERFUL AND SELECTIVE REDUCING AGENT SODIUM BOROHYDRIDE-PALLADIUM CHLORIDE SYSTEM
Satoh, Toshio,Mitsuo, Naoki,Nishiki, Mayumi,Nanba, Kenryo,Suzuki, Shuichi
, p. 1029 - 1030 (2007/10/02)
A new reducing agent, sodium borohydride-palladium chloride system reduces aryl ketones, aryl chlorides, and benzylic alcohols to corresponding hydrocarbons.It also reduces hindered steroidal ketones to alcohols in good yields.
