- Domino Prins/pinacol reaction for the stereoselective synthesis of spiro[pyran-4,4′-quinoline]-2′,3′-dione derivatives
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A wide array of aldehydes undergo smooth cross-coupling with 3-hydroxy-3-(4-hydroxybut-1-en-2-yl)-1-methylindolin-2-one in the presence of 10 mol% BF3·OEt2 at 0 °C in dichloromethane to afford the corresponding 2,3,5,6-tetrahydro-1′H-spiro[pyran-4,4′-quinoline]-2′,3′-dione derivatives in good yields with excellent diastereoselectivity. This is the first report on the synthesis of tetrahydro-1′H-spiro[pyran-4,4′-quinoline]-2′,3′-dione scaffolds through a cascade of Prins/pinacol reactions.
- Subba Reddy,Gopal Reddy,Durgaprasad,Bhadra, Manika Pal,Sridhar
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- BORONIC ACID DERIVATIVES AND THERAPEUTIC USES THEREOF
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Disclosed herein are antimicrobial compounds, compositions, pharmaceutical compositions, the use and preparation thereof. Some embodiments relate to boronic acid derivatives and their use a therapeutic agents.
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Paragraph 0210
(2019/11/12)
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- Photoredox-Catalyzed Cyclopropanation of 1,1-Disubstituted Alkenes via Radical-Polar Crossover Process
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The photoredox-neutral catalyzed cyclopropanation of 1,1-disubstituted alkenes via radical addition-anionic cyclization cascade has been successfully developed. Another new protocol based on photocatalytic allylation and cyclopropanation cascade was also described between allylic halide and halomethyl radical. In addition to the successful use of bis-catecholato silicates as the alkyl radical precursors, the acyl and alkyl radicals derived from 1,4-dihydropyridines were also engaged in this radical-polar crossover process. The competing experiments displayed that the 3-exo-tet mode of cyclization preferred over 4-exo and 5-exo cyclization modes, allowing for the selective 3-exo-tet cyclization. The superior nucleofuge character of bromide over chloride and tosylate has been demonstrated in the reaction of bromomethyl radical with homoallylic (pseudo)halides. This new protocol is characterized by its redox-neutral process, broad substrate scope, mild conditions, and good functional-group compatibility. (Figure presented.).
- Luo, Wenping,Yang, Yi,Fang, Yewen,Zhang, Xinxin,Jin, Xiaoping,Zhao, Guicai,Zhang, Li,Li, Yan,Zhou, Wanli,Xia, Tingting,Chen, Bin
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supporting information
p. 4215 - 4221
(2019/08/16)
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- Ring strain-dictated divergent fluorinating Prins cyclization or semipinacol rearrangement
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We have developed ring-strain dictated divergent diastereoselective fluorinating Prins cyclization reactions or semipinacol rearrangement reactions to access tetrahydropyrans containing a fluorohydrin or a carbonyl moiety at quaternary carbon centers under mild conditions, respectively.
- Liu, Yi,Yeung, Ying-Yeung
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supporting information
p. 6478 - 6482
(2017/08/16)
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- Hydroalumination of terminal β-acetylene alcohols with lithium aluminum hydride
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Hydrogenation of terminal β-acetylene alcohols with lithium aluminum hydride in THF has afforded homoallylic alcohols. Decomposition of the intermediate organoaluminum complex with deuterated water, iodine, or pyridinium dibromide has evidenced about the non-regioselective hydride attack at the triple bond.
- Garibyan,Makaryan,Ogannisyan,Chobanyan
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p. 267 - 272
(2016/04/20)
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- Ynamide Carbopalladation: A Flexible Route to Mono-, Bi- and Tricyclic Azacycles
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Bromoenynamides represent precursors to a diversity of azacycles by a cascade sequence of carbopalladation followed by cross-coupling/electrocyclization, or reduction processes. Full details of our investigations into intramolecular ynamide carbopalladation are disclosed, which include the first examples of carbopalladation/cross-coupling reactions using potassium organotrifluoroborate salts; and an understanding of factors influencing the success of these processes, including ring size, and the nature of the coupling partner. Additional mechanistic observations are reported, such as the isolation of triene intermediates for electrocyclization. A variety of hetero-Diels-Alder reactions using the product heterocycles are also described, which provide insight into Diels-Alder regioselectivity.
- Campbell, Craig D.,Greenaway, Rebecca L.,Holton, Oliver T.,Walker, P. Ross,Chapman, Helen A.,Russell, C. Adam,Carr, Greg,Thomson, Amber L.,Anderson, Edward A.
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supporting information
p. 12627 - 12639
(2015/09/01)
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- Tandem Prins/pinacol reaction for the synthesis of oxaspiro[4.5]decan-1-one scaffolds
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A novel Lewis acid catalyzed Prins/pinacol cascade process has been developed for the synthesis of 7-substituted-8-oxaspiro[4.5]decan-1-ones in good yields with excellent selectivity. This is the first example of the synthesis of oxaspirocycles from aldehydes and 1-(4-hydroxybut-1-en-2-yl)cyclobutanol through a cascade of Prins/pinacol rearrangement. This method is applicable to a wide range of aldehydes such as aromatic, aliphatic, heteroaromatic, and α,β-unsaturated aldehydes. This journal is the Partner Organisations 2014.
- Subba Reddy,Gopal Reddy,Ramana Reddy,Pal Bhadra, Manika,Sarma
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supporting information
p. 7257 - 7260
(2014/11/07)
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- Diastereoselective palladium-catalyzed arylcyanation/heteroarylcyanation of enantioenriched N -allylcarboxamides
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A diastereoselective Pd-catalyzed arylcyanation/heteroarylcyanation of chiral N-allylcarboxamides using Zn(CN)2 as the cyanide source is reported. Nitrile-containing dihydroisoquinolinone products are obtained in good to excellent yields with u
- Yoon, Hyung,Petrone, David A.,Lautens, Mark
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supporting information
p. 6420 - 6423
(2015/02/05)
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- Reductive cyclization of bromoenynamides with alcohols as hydride source: Synthesis and reactions of 2-amidodienes
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Under basic conditions in alcoholic solvents, bromoenynamides undergo palladium-catalyzed cyclization to cyclic 2-amidodienes in good to excellent yields. This process represents the first use of an alcohol as a hydride source in an alkyne carbopalladation/termination sequence, with the site selectivity of the reduction showing a strong dependence on the tethering ring size (5-8), and the nature of the alcohol and base. Reaction of the dienes with a range of dienophiles (including alkenes, alkynes and arynes) under various conditions gives bi- and tricyclic azacycles, which can be further oxidized to the aromatic azacycles. Copyright
- Greenaway, Rebecca L.,Campbell, Craig D.,Chapman, Helen A.,Anderson, Edward A.
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supporting information
p. 3187 - 3194
(2013/01/15)
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- SnCl2/KI-mediated allylation reactions of formaldehyde in water
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An efficient procedure for SnCl2/KI-mediated allylation reactions of formaldehyde with a variety of allylic bromides in aqueous solution is reported. Under conditions developed in this effort, various homoallylic alcohols and 2-halohomoallylic alcohols are produced in good to excellent yields. Georg Thieme Verlag Stuttgart New York.
- Lin, Mei-Huey,Lin, Long-Zhi,Chuang, Tsung-Hsun
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supporting information; experimental part
p. 1871 - 1874
(2011/09/16)
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- Palladium-catalyzed cascade cyclization of ynamides to azabicycles
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Cascade reactions: A modular assembly of azabicycles by using a cascade cyclization/Suzuki coupling/6π-electrocyclization of bromoenynamides is reported (see scheme). The reaction offers a wide substituent scope on the bicyclic aminodiene products, which can be selectively oxidized as a general approach to aromatic azabicycles.
- Greenaway, Rebecca L.,Campbell, Craig D.,Holton, Oliver T.,Russell, C. Adam,Anderson, Edward A.
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supporting information; scheme or table
p. 14366 - 14370
(2012/02/04)
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- A simple microwave-assisted preparation of 2-bromo-1-alkenes from 1-alkynes using the LiBr-TMSCl-TEAB reagent system
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2-Bromo-1-alkenes are cleanly and conveniently generated in good yields and selectivities via microwave-assisted hydrobromination of 1-alkynes using a combination of lithium bromide (LiBr), chlorotrimethylsilane (TMSCl), and tetraethylammonium bromide (TEAB) in acetonitrile (MeCN).
- Bunrit, Anon,Ruchirawat, Somsak,Thongsornkleeb, Charnsak
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supporting information; experimental part
p. 3124 - 3127
(2011/06/26)
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- Preference of β-lactam formation in Cu(I)-catalyzed intramolecular coupling of amides with vinyl bromides
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(Chemical Equation Presented) A general and highly efficient synthesis of 4-alkylidene-2-azetidinones was achieved by the Cu(I)-catalyzed intramolecular C-N coupling of amides with vinyl bromides. This 4-exo ring closure was found to be fundamentally preferred over other modes (5-exo, 6-exo, and 6-endo) of cyclization under copper catalysis. Tandem C-N bond formation was then successfully developed to allow the convenient generation of medium-sized lactams.
- Zhao, Qiwu,Li, Chaozhong
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supporting information; experimental part
p. 4037 - 4040
(2009/05/27)
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- Cu(I)-catalyzed intramolecular C-C coupling of activated methylene compounds with vinyl halides: Efficient synthesis of functionalized alkylidenecyclobutanes
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(Chemical Equation Presented) With the catalysis of Cul/L-proline, a number of 2-(3-bromobut-3-enyl)malonates underwent efficient intramolecular C-vinylation leading to the synthesis of functionalized alkylidenecyclobutanes. Competition experiments reveal
- Chen, Liqun,Shi, Min,Li, Chaozhong
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supporting information; scheme or table
p. 5285 - 5288
(2009/06/18)
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- Thermally-induced 1,2-shifts to convert olefins to carbenes: Does silicon do it? if so, why not carbon?
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Thermal isomerization of olefins to carbenes via a 1,2-silyl shift was examined by both experiment and theory. No evidence of this rearrangement was found for acyclic vinylsilanes, nor could electronic assistance by silicon be identified in cis, trans isomerizations. Serendipitous synthesis of a 2,4-dimethylene-1,3-disilacyclobutane allowed a kinetic examination of its gas-phase, thermal ring expansion to a 2-methylene-1,3-disilacyclopentene. The Arrhenius parameters (log A = 12.48, Eact = 54.09 kcal/mol) are the first to be reported for an olefin-to-carbene rearrangement. The analogous all-carbon system failed to ring expand. Ab initio calculations revealed that this was opposite to any predictions which would be made from ring strain considerations. Calculations showed that for silyl migration the transition state was late and was actually the carbene, while for carbon migration the TS was early and considerably higher in energy than the resulting carbene. The 2-methylene-1-silacyclobutane rearrangement (ref 5) was reexamined to find that reversible ring opening to a 1,4-diradical occurred at temperatures below those required to ring expand via a carbene TS.
- Barton, Thomas J.,Lin, Jibing,Ijadi-Maghsoodi, Sina,Power, Martin D.,Zhang, Xianping,Ma, Zhongxin,Shimizu, Hideaki,Gordon, Mark S.
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p. 11695 - 11703
(2007/10/03)
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- A CONCISE SYNTHESIS OF (+/-) CHOKOL A
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The fungitoxic sesquiterpene chokol A was synthesized via a six step sequence which used the addition reaction of a functionalised cuprate reagent to cyclopentenone as the key step.
- Lawler, David M.,Simpkins, Nigel S.
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p. 1207 - 1208
(2007/10/02)
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- Silicon in Synthesis. 21. Reagents for Thiophenyl-Functionalized Cyclopentenone Annulations and the Total Synthesis of (+/-)-Hirsutene
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1-(Trimethylsilyl)-1-(phenylthio)ethylene (1) reacts with cyclic α,β-unsaturated acid chlorides to give β-mercaptophenyl-substituted cyclopentenones, whereas 1-(trimethylsilyl)-2-(phenylthio)ethylene (2) under similar conditions results in thiophenyl migr
- Magnus, Philip,Quagliato, Dominick
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p. 1621 - 1626
(2007/10/02)
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- Palladium-Catalyzed Cyclizations of Bromodialkenyl Ethers and Amines
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A variety of vinylic bromoalkenyl alkenyl ethers were reacted with piperidine and a palladium acetate-tri-o-tolylphosphine catalyst.Intramolecular vinylic substitution occurred in many cases.Five-membered rings formed most easily, followed by six and then
- Shi, L.,Narula, C. K.,Mak, K. T.,Kao, L.,Xu, Y.,Heck, R. F.
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p. 3894 - 3900
(2007/10/02)
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