- Merging Halogen-Atom Transfer (XAT) and Cobalt Catalysis to Override E2-Selectivity in the Elimination of Alkyl Halides: A Mild Route towardcontra-Thermodynamic Olefins
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We report here a mechanistically distinct tactic to carry E2-type eliminations on alkyl halides. This strategy exploits the interplay of α-aminoalkyl radical-mediated halogen-atom transfer (XAT) with desaturative cobalt catalysis. The methodology is high-yielding, tolerates many functionalities, and was used to access industrially relevant materials. In contrast to thermal E2 eliminations where unsymmetrical substrates give regioisomeric mixtures, this approach enables, by fine-tuning of the electronic and steric properties of the cobalt catalyst, to obtain high olefin positional selectivity. This unprecedented mechanistic feature has allowed access tocontra-thermodynamic olefins, elusive by E2 eliminations.
- Zhao, Huaibo,McMillan, Alastair J.,Constantin, Timothée,Mykura, Rory C.,Juliá, Fabio,Leonori, Daniele
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p. 14806 - 14813
(2021/09/18)
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- Alkynylation of steroids via Pd-free Sonogashira coupling
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Cu-catalyzed Pd-free Sonogashira coupling has been proposed as a straightforward and convenient route to valuable steroidal enynes. A biligand catalyst system based on Ph3P and TMEDA has been designed. The protocol was utilized for the efficient coupling of iodosteroids with diverse terminal alkynes and 1-trimethylsilylalkynes. A possible role of an auxiliary ligand as a phase-transfer catalyst for a sparingly soluble inorganic base (K2CO3) was revealed.
- Kotovshchikov, Yury N.,Latyshev, Gennadij V.,Lukashev, Nikolay V.,Beletskaya, Irina P.
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p. 5542 - 5555
(2015/05/20)
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- An efficient approach to azolyl-substituted steroids through copper-catalyzed Ullmann C-N coupling
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Ullmann-type C-N coupling of vinyliodides and nitrogen heterocycles has been shown to be a straightforward and highly efficient approach to azolyl-substituted steroids. The amination reaction proved sensitive to steric effects exerted by the substituents in both iodide and heterocycle. The influence of reaction conditions (catalyst, base, solvent, and temperature) on conversion of the iodosteroid and the selectivity was investigated. The catalytic system comprising 10 mol-% CuI and 20 mol-% dipivaloylmethane with K2CO3 in dimethyl sulfoxide at 100 °C delivered the best result. The elaborated protocol has permitted iodosteroids with various substituted indoles, imidazoles, carbazole, indazole, and sec-amides to be coupled, affording the corresponding azolyl-substituted steroids in good to excellent yields. A facile synthetic route to azolyl-substituted steroids has been developed on the basis of Cu-catalyzed cross-coupling of steroidal vinyliodides and aromatic NH-heterocycles. The protocol has been shown to be convenient and highly efficient, affording coupling products in good to excellent yields. Copyright
- Kotovshchikov, Yury N.,Latyshev, Gennadij V.,Lukashev, Nikolay V.,Beletskaya, Irina P.
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p. 7823 - 7832
(2013/12/04)
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- Convenient synthesis of monomeric steroids from steroidal oxalate dimers using flash vacuum pyrolysis (FVP)
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Flash vacuum pyrolysis (FVP) or thermolysis (FVT), an environmentally friendly method for studying organic reaction mechanisms as well as synthesis, was applied to a series of oxalate dimers (1, 3, 5, 7, 9, 11, 13, and 15) to synthesise monomeric enes, dienes, and a triene (2, 4, 6, 8, 10, 12, 14, and 16). All steroidal monomers were identified by spectroscopic means. TUBITAK.
- Nahar, Lutfun,Turner, Alan B.,Sarker, Satyajit D.
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experimental part
p. 359 - 366
(2010/11/03)
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- Androstane steroids as neurochemical initiators of change in human hypothalamic function and related pharmaceutical compositions and methods
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The invention relates to a method of altering hypothalamic function in an individual. The method comprises nasally administering a human semiochemical, e.g. an Androstane steroid, or a pharmaceutical composition containing a semiochemical, such that the ligand semiochemical binds to a specific neuroepithelial receptor. The steroid or steroids is/are preferably administered in the form of a pharmaceutical composition containing one or more pharmaceutically acceptable carriers. Other embodiments of the invention include pharmaceutical compositions containing the steroids.
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- Steroids as neurochemical stimulators of the VNO to alleviate pain
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The invention relates to a method of alleviating pain. The method comprises nasally administering a steroid which is a human vomeropherin, such that the vomeropherin binds to a specific neuroepithelial receptor. The steroid or steroids is/are preferably administered in the form of a pharmaceutical composition containing one or more pharmaceutically acceptable carriers.
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- Synthesis of trichiliasterones A and B - 16-ketosteroids isolated from Trichilia hirta and Trichilia americana
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The syntheses of trichiliasterone A (3b-hydroxypregnan-2,16-dione) and trichiliasterone B (2-hydroxyandrost-1,4-diene-3,16-dione) have been carried out starting from isoandrosterone and testosterone acetate, respectively. In each synthesis the functionality in the D ring was installed prior to working on ring A. In the case of trichiliasterone A, the D ring chemistry involved a Wittig reaction to generate the 17-methylene group, followed by SeO2 oxidation to give an a,b-unsaturated ketone. Reaction with lithium dimethyl cuprate gave the required 17-ethyl-16-keto functionality. A 2,3-epoxy enol acetate served as the key intermediate for the generation of the 2-keto-3-hydroxy functions in ring A. The transposition of the keto function from C-16 to C-17 in the synthesis of trichiliasterone B was accomplished via oxymercuration-demercuration of the D16-17 double bond followed by oxidation. The hydroxyl group at C-2 and the additional ring A unsaturation were introduced by lead tetra-acetate treatment of the 3-keto-4-enone function and subsequent air oxidation.
- Hantos, Susanne M.,Tripathy, Sasmita,Alibhai, Najma,Durst, Tony
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p. 1747 - 1753
(2007/10/03)
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- Steroids as neurochemical stimulators of the VNO to treat paroxistic tachycardia
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The invention relates to a method of alleviating the symptoms of PMS and anxiety. The method comprises nasally administering a steroid which is a human vomeropherin, such that the vomeropherin binds to a specific neuroepithelial receptor. The steroid or steroids is/are preferably administered in the form of a pharmaceutical composition containing one or more pharmaceutically acceptable carriers.
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- Steroids as neurochemical stimulators of the VNO to alleviate symptoms of PMS and anxiety
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The invention relates to a method of alleviating the symptoms of PMS and anxiety. The method comprises nasally administering a steroid which is a human vomeropherin, such that the vomeropherin binds to a specific neuroepithelial receptor. The steroid or steroids is/are preferably administered in the form of a pharmaceutical composition containing one or more pharmaceutically acceptable carriers.
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- Steroids as neurochemical initiators of change in human blood levels of LH
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The invention relates to a method of altering the blood levels of LH or FSH in an individual. The method comprises nasally administering a steroid which is a human vomeropherin, such that the vomeropherin binds to a specific neuroepithelial receptor. The steroid or steroids is/are preferably administered in the form of a pharmaceutical composition containing one or more pharmaceutically acceptable carriers.
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- Androstanes for inducing hypothalamic effects
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The invention relates to novel, androstane steroids which are the ligand semiochemicals which bind to neuroepithelial receptors. The steroids are useful as ligands to neuroepithelial receptors in the human vomeronasal gland to stimulate autonomic and hypothalamic activity.
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- Chloromethanesulfonate as an efficient leaving group: Rearrangement of the carbon-carbon bond and conversion of alcohols into azides and nitriles
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The chloromethanesulfonate (monochlate) served as an efficient leaving group for rearrangement of the carbon-carbon bond and conversion of alcohols into azides and nitriles. The treatment of the monochlate 16a with zinc acetate in dioxane at 90 °C effected migration of the 4α-methyl group to give alkene 17a. Upon similar treatment of the monochlates 22a, 25a, 28a, and 31a with zinc acetate, the carbon-carbon bonds antiperiplanar to the hydroxyl groups efficiently migrated to afford the alkenes 23a, 26a-c, 29a,b, and 32a, respectively. In the case of the diol 40, the monochlate was converted into the ketone 41 via a rearrangement-ring expansion. The reaction of the monochlates 44a, 47a, 49a, 52a, and 57a with sodium azide or lithium azide in N,N-dimethylformamide efficiently afforded the azides with inversion of the configuration. The introduction of a nitrile group to the sterically hindered alcohol 59 was performed in high yield by the reaction of the monochlate 60a with sodium cyanide.
- Shimizu, Takeshi,Ohzeki, Tomoya,Hiramoto, Katsuya,Hori, Nobuyuki,Nakata, Tadashi
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p. 1373 - 1385
(2007/10/03)
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- Efficient method for inversion of secondary alcohols by reaction of chloromethanesulfonates with cesium acetate
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Inversion of a variety of secondary alcohols using the (chloromethylsulfonyl)oxy group as a favorable leaving group with cesium acetate in the presence of 18-crown-6 has been performed to give the inverted acetates in high yields.
- Shimizu, Takeshi,Hiranuma, Sayoko,Nakata, Tadashi
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p. 6145 - 6148
(2007/10/03)
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- Fragrance compositions and other compositions which contain human pheromones
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The invention concerns novel, non-therapeutic fragrance compositions and other compositions containing an odorant and a naturally occurring human pheromone. The invention also concerns fragrance compositions containing mixtures of naturally occurring human pheromones. The human pheromones disclosed are steroids which desirably belong to two distinct chemical classes: 16-Androstenes and Estrenes.
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- 16-Dehydro steroids of the androstane series
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Therapeutically useful 16-dehydro-androstane derivatives of the general formula: STR1 processes for their preparation and pharmaceutical compositions for the treatment of dermatological disorders, which contain as active ingredient at least one of the 16-dehydro-androstane derivatives as defined by the above formula.
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