- Application of a novel directing effect in an organocoppoer/orthoester reaction to the synthesis of deuterium labeled unsaturated esters
-
Deuterium labeled methacrylates (5,6), tiglates (10,12), and senecioates (13,14,16,17), important for biosynthetic studies on the synthesis of carboxylic acids in carabid beetles, have been prepared using organocopper-alkyne coupling reactions. With 1,1,1,-triethoxypropyne as a coupling partner, a novel directing effect was observed; the 'branched' product was formed exclusively.
- Shattuck, James C.,Svatos, Ales,Blazey, Charles M.,Meinwald, Jerrold
-
-
Read Online
- Synthesis of Substituted 1-Alkylidenephthalanes via Lithium-Promoted 5-exo-dig Cyclization
-
A one-pot synthesis of 1-alkylidenephthalanes from 3-(2-bromophenyl)propyne derivatives has been developed. 3-(2-Bromophenyl)propynal acetals 9 and corresponding orthoester 19 were treated successively with n-butyllithium and various aldehydes and ketones at low temperature to obtain 1-alkylidenephthalanes 10 and 20 with various functional groups at the exocyclic methylene moiety. Halogen-metal exchange, nucleophilic addition to various carbonyl compounds, regioselective 5-exo-dig cyclization of the respective intermediate lithium alcoholate and hydrolysis represent the key steps in this Domino reaction. A two-step mechanism involving at first a synchronous cyclization to form a vinyllithium intermediate and then a methoxide elimination leading to the respective 1-methoxy allenes is suggested based on DFT-calculations.
- Bunse, Paul,Würthwein, Ernst-Ulrich,Wünsch, Bernhard
-
supporting information
p. 1806 - 1812
(2018/04/27)
-
- An acyclic enediyne anticancer compound attributed to a Bergman cyclization at physiological temperature
-
Enediyne cytotoxic drugs have attracted much attention because of their unique structure and potent anticancer activity. However, acyclic enediynes are long considered as inactive at physiological temperature due to their long C1-C6 distance. By adjusting the steric bulkiness of the functional groups at the alkynyl termini and the electron-withdrawing effect at the ene moiety, herein, a simple acyclic enediyne was designed and synthesized to achieve the onset of thermal Bergman cyclization at physiological temperature in polar solvents. The spontaneous generation of diradical intermediates was confirmed through EPR analysis and further supported by spin trapping experiment, radical indicator experiment, and high resolution MS analysis. The reactive diradicals generated in aqueous media induced single and double stranded cleavage of DNA, and showed high cytotoxicity to Hela cells. The IC50 value of the enediyne compound is comparable to many clinical used anti-tumor agents.
- Li, Baojun,Duan, Bing,Li, Jing,Zhang, Mengsi,Yuan, Yuan,Ding, Yun,Hu, Aiguo
-
supporting information
p. 6419 - 6425
(2018/10/02)
-
- Self-assembled orthoester cryptands: Orthoester scope, post-functionalization, kinetic locking and tunable degradation kinetics
-
Dynamic adaptability and biodegradability are key features of functional, 21st century host-guest systems. We have recently discovered a class of tripodal supramolecular hosts, in which two orthoesters act as constitutionally dynamic bridgeheads. Having previously demonstrated the adaptive nature of these hosts, we now report the synthesis and characterization-including eight solid state structures-of a diverse set of orthoester cages, which provides evidence for the broad scope of this new host class. With the same set of compounds, we demonstrated that the rates of orthoester exchange and hydrolysis can be tuned over a remarkably wide range, from rapid hydrolysis at pH 8 to nearly inert at pH 1, and that the Taft parameter of the orthoester substituent allows an adequate prediction of the reaction kinetics. Moreover, the synthesis of an alkyne-capped cryptand enabled the post-functionalization of orthoester cryptands by Sonogashira and CuAAC "click" reactions. The methylation of the resulting triazole furnished a cryptate that was kinetically inert towards orthoester exchange and hydrolysis at pH > 1, which is equivalent to the "turnoff" of constitutionally dynamic imines by means of reduction. These findings indicate that orthoester cages may be more broadly useful than anticipated, e.g. as drug delivery agents with precisely tunable biodegradability or, thanks to the kinetic locking strategy, as ion sensors.
- L?w, Henrik,Mena-Osteritz, Elena,Von Delius, Max
-
p. 4785 - 4793
(2018/06/07)
-
- Practical synthesis of functionalized terminal alkynes, 3,3,3-triethoxypropyne and ketal protected prop-2-ynones
-
Practical and economical synthesis of synthetically valuable 3,3,3-triethoxypropyne, ketal protected phenyl and methyl substituents prop-2-ynones is described. Bromination and subsequent 18-crown-6 catalyzed elimination of triethylorthoacrylate and ketal
- Karanfil, Abdullah,Eskici, Mustafa
-
p. 2342 - 2351
(2017/12/12)
-
- Maleimide-based acyclic enediyne for efficient DNA-cleavage and tumor cell suppression
-
A pH-sensitive acyclic enediyne (1) was synthesized for efficient DNA-cleavage and tumor cell suppression. Unlike other acyclic enediynes, this novel enediyne transforms into a highly reactive enediyne (2) in an acidic environment only, which undergoes Be
- Song, Depeng,Sun, Shiyuan,Tian, Yu,Huang, Shuai,Ding, Yun,Yuan, Yuan,Hu, Aiguo
-
supporting information
p. 3195 - 3200
(2015/04/27)
-
- Direct, catalytic synthesis of carbapenams via cycloaddition/rearrangement cascade reaction: Unexpected acetylenes' structure effect
-
Reactions of acetylenes derived from glyceraldehyde and propargyl aldehyde show remarkable reactivity in Kinugasa cycloaddition/rearrangement cascade process catalyzed by Cu(I) ion. Reactions proceed by formation of a rigid dinuclear copper(I) complex in which each copper ion is coordinated to one or both oxygen atoms in the acetylene molecule and to both triple bonds. It has been demonstrated that one oxygen atom can be replaced by the phenyl ring, which is able to coordinate the copper ion by the aromatic sextet. Kinugasa reactions that proceed in a high yield can also be performed in the presence of a catalytic amount of the copper salt to provide products in an acceptable yield without a decrease of diastereoselectivity.
- Mames, Adam,Stecko, Sebastian,Mikolajczyk, Paulina,Soluch, Magdalena,Furman, Bartlomiej,Chmielewski, Marek
-
supporting information; experimental part
p. 7580 - 7587
(2011/03/17)
-
- Synthesis and photophysical properties of novel cyclonucleosides-substituent effects on fluorescence emission
-
An intramolecular [3+2]-cycloaddition between an azide and a disubstituted alkyne afforded a number of novel adenosine-derived cyclonucleosides, which exhibited fluorescence in the visible range. The synthesis and photophysical properties of these potenti
- O'Mahony, Gavin,Ehrman, Eleonor,Gr?tli, Morten
-
p. 7151 - 7158
(2008/12/20)
-
- NAPHTHALENONE COMPOUNDS EXHIBITING PROLYL HYDROXYLASE INHIBITORY ACTIVITY, COMPOSITIONS, AND USES THEREOF
-
Compounds of Formula (I) and Formula (II) are useful as inhibitors of HIF prolyl hydroxylases. Compounds of Formula(I) and Formula (II) have the following structures, where the definitions of the variables are provided herein.
- -
-
Page/Page column 186-187; 192
(2008/12/06)
-
- Substituted indoles and their use as integrin antagonists
-
The present invention relates to novel substituted indole compounds that are antagonists of alpha V (αv) integrins, for example αvβ3 and αvβ5 integrins, their pharmaceutically acceptable salts, and pharmaceutical compositions thereof. The compounds may be used in the treatment of pathological conditions mediated by αvβ3 and αvβ5 integrins, including such conditions as tumor growth, metastasis, restenosis, osteoporosis, inflammation, macular degeneration, diabetic retinopathy, and rheumatoid arthritis. The compounds have the general formula: where R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, D, X, W, a, m, n, i, j, k and v are defined herein.
- -
-
-
- Preparation of camptothecin and of its derivatives
-
The present invention relates to a novel process for preparation of camptothecin and of its derivatives by convergent synthesis starting from a 3-(aminomethyl)quinoline derivative and 5-hydroxy-5-ethyl-6-oxo-5,6-dihydropyrancarboxylic acid and to the intermediates obtained.
- -
-
-
- Ethynyl Ortho Esters as Precursors of Propargyl Cations. The Low-Temperature, Ionic Diels-Alder Addition of Ethyl Propiolate to 1,3-Dienes via Ethynyl Ortho Esters
-
3,3,3-Triethoxypropyne (triethyl orthopropiolate) was added to a series of 1,3-dienes at low temperature in the presence of trimethylsilyl triflate to yield the 4? + 2? products of the formal addition of ethyl propiolate to the 1,3-dienes.
- Gassman, Paul G.,Chavan, Subhash P.
-
p. 3407 - 3410
(2007/10/02)
-
- TRIMETHYLSILYL ETHYL ORTHOPROPIOLATE - PREPARATION AND USE AS A PROPIOLATE ANION EQUIVALENT
-
Lithio ethyl orthopropiolate (4b), prepared from trimethylsilyl ethyl orthopropiolate (4a), is introduced as an easy to handle propiolate anion (1a) equivalent.
- Boche, Gernot,Bigalke, Juergen
-
p. 955 - 958
(2007/10/02)
-