- Synthesis of 2- and 17-substituted estrone analogs and their antiproliferative structure-activity relationships compared to 2-methoxyestradiol
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A novel series of 17-modified and 2,17-modified analogs of 2-methoxyestradiol (2ME2) were synthesized and characterized. These analogs were designed to retain or potentiate the biological activities of 2ME2 and have diminished metabolic liability. The ana
- Shah, Jamshed H.,Agoston, Gregory E.,Suwandi, Lita,Hunsucker, Kimberly,Pribluda, Victor,Zhan, Xiaoguo H.,Swartz, Glenn M.,LaVallee, Theresa M.,Treston, Anthony M.
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Read Online
- A general strategy for the stereocontrolled preparation of diverse 8- and 9-membered Laurencia -type bromoethers
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A unique procedure to effect a ring-expanding bromoetherification process is described, wherein tetrahydrofurans and tetrahydropyrans are smoothly transformed into 8- and 9-membered bromoethers in a regio- and stereocontrolled manner through the use of BDSB (bromodiethylsulfonium bromopentachloroantimonate). These products resemble the cores of the Laurencia C15 acetogenins. In light of the generality and effectiveness of the approach, this work provides a unique strategy for their laboratory preparation and may implicate a possible biosynthesis pathway.
- Snyder, Scott A.,Treitler, Daniel S.,Brucks, Alexandria P.,Sattler, Wesley
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- Heavier Carbonyl Olefination: The Sila-Wittig Reaction
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The Wittig reaction is one of the most versatile tools in the repertoire of organic chemists. Thus, a broad variety of carbonyl compounds can be converted to tailor-made alkenes with phosphorus ylides under mild conditions. However, no comparable reaction has been reported for silanones, the silicon congeners of ketones. Here, we demonstrate for the first time the successful application of the Wittig olefination to iminosilylsilanone 1. The selective formation of a series of silenes (R2Sia? CR2) via the sila-Wittig reaction revealed an unprecedented approach to otherwise elusive compounds. In addition, the highly reactive and zwitterionic nature of 1 was also susceptible to nucleophilic attacks and cycloaddition reactions by and with the phosphorus ylides. Our results therefore make another important contribution to discovering the differences and similarities between carbon and silicon.
- Reiter, Dominik,Frisch, Philipp,Szilvási, Tibor,Inoue, Shigeyoshi
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supporting information
p. 16991 - 16996
(2019/10/16)
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- Synthetic and Spectroscopic Investigations Enabled by Modular Synthesis of Molecular Phosphaalkyne Precursors
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A series of dibenzo-7-phosphanorbornadiene compounds, Ph3PC(R)PA (1-R; A = C14H10, anthracene; R = Me, Et, iPr, sBu), are reported to be capable of thermal fragmentation to generate alkyl-substituted phosphaalkynes (RC≡P) concomitant with triphenylphosphine and anthracene. Facile preparation of these molecular precursors proceeds by treatment of ClPA with the appropriate ylide Ph3P=CHR (2 equiv). For methyl, ethyl, and isopropyl substituents, the phosphaalkyne conversions are measured to be 56-73% in solution by quantitative 31P NMR spectroscopy. In the case of compound 1-Me, the kinetic profile of its spontaneous unimolecular fragmentation is investigated by an Eyring analysis. The resulting 1-phosphapropyne is directly detected by solution NMR spectroscopy and gas phase rotational microwave spectroscopy. The latter technique allows for the first time measurement of the phosphorus-31 nuclear spin-rotation coupling tensor. The nuclear spin-rotation coupling provides a link between rotational and NMR spectroscopies, and is contextualized in relation to the chemical shift anisotropy.
- Transue, Wesley J.,Yang, Junyu,Nava, Matthew,Sergeyev, Ivan V.,Barnum, Timothy J.,McCarthy, Michael C.,Cummins, Christopher C.
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supporting information
p. 17985 - 17991
(2019/01/09)
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- Enantioselective palladium-catalyzed addition of malonates to 3,3-difluoropropenes
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Monofluoroalkenes bearing a malonate unit at the β position can be synthesized by the enantioselective addition of diesters to 3,3-difluoropropenes. The difference in reactivity regarding the geometry and the substituents of the alkene of the 3,3-difluoropropenes, as well as the alkyl groups of the malonates, was studied and limitations were identified. The reaction was also performed with different 3,3-difluoropropenes. Further synthetic transformations of a newly functionalized monofluoroalkene were also accomplished.
- Drouin, Myriam,Paquin, Jean-Fran?ois
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supporting information
p. 6023 - 6032
(2018/09/11)
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- Olefin metathesis based approach to diversely functionalized pyrrolizidines and indolizidines; total synthesis of (+)-monomorine
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New scaffolds for the stereoselective synthesis of diversely functionalized chiral enantiopure indolizidines and pyrrolidines were synthesized from the cross and ring-closing metathesis reactions of appropriate intermediates, readily available from L-pyroglutamic acid. The versatility of this strategy was demonstrated by the synthesis of an indolizidine-based azasugar analogue and of the natural alkaloid (+)-monomorine.
- Lesma, Giordano,Colombo, Alessia,Sacchetti, Alessandro,Silvani, Alessandra
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experimental part
p. 590 - 596
(2009/06/20)
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- Synthesis of (+)-coronafacic acid
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An enantioselective synthesis of (+)-coronafacic acid has been achieved. Rhodium-catalyzed cyclization of an a-diazoester provided the intermediate cyclopentanone in high enantiomeric purity. Subsequent Fe-mediated cyclocarbonylation of a derived alkenyl
- Taber, Douglass F.,Sheth, Ritesh B.,Tian, Weiwei
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supporting information; experimental part
p. 2433 - 2437
(2009/07/25)
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- A new catalytic Cu(II)/sparteine oxidant system for β,β-phenolic couplings of styrenyl phenols: Synthesis of carpanone and unnatural analogs
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(Chemical Equation Presented) A new catalytic Cu(ll)/sparteine system has been developed to promote β,β-phenolic couplings of styrenyl phenols en route to carpanone and related unnatural congeners in yields exceeding 85%.
- Daniels, R. Nathan,Fadeyi, Olugbeminiyi O.,Lindsley, Craig W.
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supporting information; experimental part
p. 4097 - 4100
(2009/05/30)
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- Total synthesis of (-)-histrionicotoxin 285A and (-)- perhydrohistrionicotoxin
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(Chemical Equation Presented) Starting from commercially available (S)-glycidol, and via a common intermediate, the total synthesis of (-)-histrionicotoxin 285A and (-)-perhydrohistrionicotoxin has been achieved. Key to this synthesis was the efficient co
- Macdonald, James M.,Horsley, Helen T.,Ryan, John H.,Saubern, Simon,Holmes, Andrew B.
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supporting information; experimental part
p. 4227 - 4229
(2009/06/06)
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- Novel synthesis of α-galactosyl-ceramides and confirmation of their powerful NKT cell agonist activity
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α-Galactosyl-ceramide (1) has been identified as a powerful modulator of immunological processes through its capacity to bind CD1d molecules and specifically activate invariant natural killer (NK)-like T cells (iNKT cells). This paper describes the synthe
- Lee, Adrianne,Farrand, Kathryn J.,Dickgreber, Nina,Hayman, Colin M.,Juers, Stefan,Hermans, Ian F.,Painter, Gavin F.
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p. 2785 - 2798
(2007/10/03)
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- Reactions of aldehydes with polymer-supported selenoalkylidenetriphenylphosphoranes. A facile method for the synthesis of carbonyl compounds
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The transylidation reactions of polymer-bound selenium bromide with alkylidenetriphenylphosphoranes 1 gave resin 2, which is sufficiently reactive to undergo Wittig-type reactions to afford the vinylic selenide resins 3. Cleavage gave ketones and aldehydes under different conditions.
- Huang, Xian,Sheng, Shou-Ri
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p. 9035 - 9037
(2007/10/03)
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- Ester compounds
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Ester compounds shown by the formula: wherein R1represents a hydrogen atom, halogen atom, C1-C3alkyl group optionally substituted by halogen atom(s), C2-C3alkenyl group optionally substituted by halogen atom(s), C1-C3alkoxy group optionally substituted by halogen atom(s), C1-C3alkylthio group optionally substituted by halogen atom(s) or (C1-C3alkoxy)methyl group optionally substituted by halogen atom(s), n represents an integer of 1 to 4 and X represents a hydrogen atom or C1-C3alkyl group, have excellent pesticidal activity.
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- First total synthesis and determination of the absolute configuration of mueggelone
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All the four possible stereoisomers of mueggelone, an inhibitor of fish development, were efficiently synthesized in a stereoselective manner starting from D-arabinose, and the absolute configuration was determined to be 9R, 12S, 13S.
- Motoyoshi, Hajime,Ishigami, Ken,Kitahara, Takeshi
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p. 3899 - 3908
(2007/10/03)
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- Ozonolysis of alkenes and study of reactions of polyfunctional compounds: LXII. New synthetic route to 7E,9Z-dodecadien-1-yl acetate, pheromone of the leaf roller moth (Lobesia botrana)
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Proceeding from the product of the partial ozonolysis of 1,4-cyclohexadiene, methyl 6-oxo-4E-hexenoate, a new synthetic route was developed to 7E,9Z-dodecadienyl acetate, pheromone of the leaf roller moth (Lobesia botrana).
- Kukovinets,Kasradze,Chernukha,Odinokov,Galin,Abdullin,Fedorov,Tolstikov
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p. 211 - 213
(2007/10/03)
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- Kinetics of proton transfer from phosphonium ions to electrogenerated bases: Polar, steric and structural influences on kinetic acidity and basicity
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Derivative cyclic voltammetry (DCV) and linear sweep voltammetry (LSV) have been used to measure rates of proton transfer in DMSO solution between different types of electrogenerated base (EGB) and a series of phosphonium ions of relevance to ylide formation for synthetic reactions. Although the electrochemical methods are convenient for the measurement of rates of proton transfer in these systems a major conclusion of the study is that considerable care must be exercised in the application of the methods and in drawing general conclusions from the results. In particular, comparison of kinetic acidity with thermodynamic pK values in DMSO shows that a single Bronsted relationship does not hold for the series of phosphonium ions. The kinetic acidities are profoundly affected by: whether the EGB is a carbon or nitrogen base; the propensity of some of the phosphonium ions to enolise; and steric factors. Other measures of electron-demand at the acidic methylene groups (13C and 1H chemical shifts, reduction potentials) are consistent with the pK(DMSO) values. The kinetic results confirm that the Ph3P+ group is, for non-enolisable phosphonium salts, more activating than Bu3P+.
- Bettencourt, Ana-Paula,Freitas, Ana Maria,Montenegro, M. Irene,Nielsen, Merete Folmer,Utley, James H. P.
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p. 515 - 522
(2007/10/03)
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- A versatile process for the syntheses of very long chain alkanes, functionalised derivatives and some branched chain hydrocarbons
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An earlier method for synthesising very long straight-chain alkanes of very specific lengths has been improved to give, in some cases, gram amounts of materials. Eleven compounds have been made: C98H198, C122H246, C162H326, C194H390, C198H398, C210H422, C242H486, C246H494, C258H518, C294H590 and C390H782. The self-condensation reaction of one of the intermediate aldehydes enabled two chain-branched hydrocarbons to be obtained: C96H193CHRC94H189 where R = CH3 and CH3(CH2)3. Three long-chain compounds containing carboxylic acid groups have been prepared: CH3(CH2)190CO2H, HO2C(CH2)48CO2H and HO2C(CH2)192CO2H. Copyright 1996 by the Royal Society of Chemistry.
- Brooke, Gerald M.,Burnett, Simon,Mohammed, Shahid,Proctor, David,Whiting, Mark C.
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p. 1635 - 1645
(2007/10/03)
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- Improved synthesis of chiral N-protected allylic amines
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The α-ester group of N-protected α-amino esters was reduced with diisobutylaluminum hydride to an intermediate aluminoxy acetal that on reaction with a Wittig reagent afforded the title chiral compounds in 48-78% chemical yields.
- Wei,Knaus
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p. 1463 - 1466
(2007/10/02)
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- Untersuchungen im Wittig-System nach einem ordnenden Konzept auf der Basis alternativer Prinzipien
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Our results show that the stereoselectivity of the Wittig-reaction can be controlled by the variation of substituents in accord with the ORDERING CONCEPT OF ALTERNATIV PRINCIPLES (individual pairs, known and unknown classes of alternatives).The "all-phenyl Wittig-system" having three phenyl groups on phosphorous two in ylid- and aldehyd-position was chosen as a standard for our investigations.Differentiation in ylid-position and compensation on phosphorous and aldehyd-position were observed by the comparison of "patterns".Consequently, most of the selectivity rules of Wittig-reactions can be explained by the differentiation through alternatives in the ylid-position.Inversion or conservation of the "patterns" of measured data points to the variation in structure of starting materials, reaction rates and selectivities.Amount-controls were also described in certain systems.
- Bandmann, Heinz,Bartik, Tamas,Bauckloh, Sylvia,Behler, Ansgar,Brille, Frank,et al.
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p. 193 - 204
(2007/10/02)
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- SYNTHESIS OF PHEROMONES, IV. CHEMISTRY OF THE WITTIG REACTION, I. EFFECTS OF REACTION CONDITIONS ON THE STEREOSELECTIVITY AND YIELD OF THE WITTIG REACTION
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The reactions of nonstabilized triphenylphosphorus ylides with aldehydes have been studied in detail.The stereochemistry and yields of the alkene products are highly dependent upon base used for the generation of the ylide, the solvent and reaction temperature.The synthesis of sex pheromone components by Wittig reaction are also described.
- Vinczer, Peter,Juvancz, Zoltan,Novak, Lajos,Szantay, Csaba
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p. 797 - 820
(2007/10/02)
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- New Liquid Crystals: The Synthesis and Mesomorphic Properties of Alkenylsubstituted Cyanophenylethylcyclohexanes and Cyanobiphenylylcyclohexanes
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Nineteen alkenylsubstituted cyanophenylethylcyclohexanes and cyanobiphenylylcyclohexanes have been synthesized by systematically varying both the position and the configuration of the isolated C,C-double bond.The influences of such structural changes on the mesomorphic properties are discussed and the observed nematic thermal stabilities (cf.Table I) are compared, where possible, with those of the corresponding saturated alkyl analogs.
- Petrzilka, Martin,Germann, Alfred
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p. 327 - 342
(2007/10/02)
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