- Ni-Catalyzed β-Alkylation of Cyclopropanol-Derived Homoenolates
-
Metal homoenolates are valuable synthetic intermediates which provide access to β-functionalized ketones. In this report, we disclose a Ni-catalyzed β-alkylation reaction of cyclopropanol-derived homoenolates using redox-active N-hydroxyphthalimide (NHPI) esters as the alkylating reagents. The reaction is compatible with 1°, 2°, and 3° NHPI esters. Mechanistic studies imply radical activation of the NHPI ester and 2e β-carbon elimination occurring on the cyclopropanol.
- Mills, L. Reginald,Zhou, Cuihan,Fung, Emily,Rousseaux, Sophie A. L.
-
supporting information
p. 8805 - 8809
(2019/11/03)
-
- Synthesis of 1-hydrocarbon substituted cyclopropyl silyl ketones
-
The synthesis of cyclopropyl silyl ketones possessing a hydrocarbon group at 1-position of three-membered ring was investigated. The reaction of sulfoxonium ylide with α,β-unsaturated acylsilanes derived from α,β-unsaturated aldehydes did not afford the desired acylsilane derivatives. Instead, the corresponding silyl enol ethers were yielded exclusively. On the other hand, the Corey-Chaykovsky cyclopropanation of α-substituted α,β-unsaturated aldehydes proceeded well to give 1-substituted cyclopropyl aldehydes. The silyl substitution of formyl proton in the obtained aldehydes via umpolung of carbonyl group afforded the target acylsilanes.
- Honda, Mitsunori,Sasaki, Sho,Nishimoto, Tsuyoshi,Koshiro, Hiromoto,Kunimoto, Ko-Ki,Segi, Masahito
-
p. 3777 - 3781
(2018/09/21)
-
- Highly Enantioselective [5 + 2] Annulations through Cooperative N-Heterocyclic Carbene (NHC) Organocatalysis and Palladium Catalysis
-
The highly enantioselective [5 + 2] annulation of enals with vinylethylene carbonates through a cooperative N-heterocyclic carbene (NHC)/Pd catalytic system is reported. The use of a bidentate phosphine ligand was crucial to prevent coordination of the NH
- Singha, Santanu,Patra, Tuhin,Daniliuc, Constantin G.,Glorius, Frank
-
supporting information
p. 3551 - 3554
(2018/03/21)
-
- Synthesis of β-Amino-Substituted Enones by Addition of Substituted Methyl Enones to Sulfinimines: Application to the Total Synthesis of Alkaloids (+)-Lasubine II and (+)-241D and the Formal Total Synthesis of (-)-Lasubine i
-
Addition of silyl enol ethers obtained from substituted methyl enones to chiral sulfinimines afforded the β-amino-substituted enones with excellent selectivity. Utility of the obtained N-sulfinyl β-amino ketones possessing α,β-unsaturation is exemplified
- Reddy, Arava Amaranadha,Reddy, Polimera Obula,Prasad, Kavirayani R.
-
p. 11363 - 11371
(2016/11/29)
-
- Novel Benzo[a]quinolizidine Analogs Induce Cancer Cell Death through Paraptosis and Apoptosis
-
Paraptosis is nonapoptotic cell death characterized by massive endoplasmic reticulum (ER)- or mitochondria-derived vacuoles. Induction of paraptosis offers significant advantages for the treatment of chemotherapy-resistant tumors compared with anticancer drugs that rely on apoptosis. Because some natural alkaloids induce paraptotic cell death, a novel series of benzo[a]quinolizidine derivatives were synthesized, and their antiproliferative activity and ability to induce cytoplasmic vacuolation were analyzed. Structural optimization led to the identification of the potent compound 22b, which inhibited cancer cell proliferation in vitro and in vivo and profoundly facilitated paraptosis-like cell death and induced caspase-dependent apoptosis. Further investigation revealed that 22b-mediated vacuolation originated from persistent ER stress and upregulation of LC3B. Paraptosis induced by benzo[a]quinolizidine derivatives thus represents an alternative strategy for cancer chemotherapy.
- Zheng, Hongbo,Dong, Yiwen,Li, Lin,Sun, Bin,Liu, Lei,Yuan, Huiqing,Lou, Hongxiang
-
p. 5063 - 5076
(2016/06/13)
-
- Conversion of Simple Cyclohexanones into Catechols
-
A novel I2-catalyzed direct conversion of cyclohexanones to substituted catechols under mild and simple conditions has been described. This novel transformation is remarkable with the multiple oxygenation and dehydrogenative aromatization processes enabled just by using DMSO as the solvent, oxidant, and oxygen source. This metal-free and simple system demonstrates a versatile protocol for the synthesis of highly valuable substituted catechols and therefore streamlines the synthesis and modification of biologically important molecules for drug discovery.
- Liang, Yu-Feng,Li, Xinyao,Wang, Xiaoyang,Zou, Miancheng,Tang, Conghui,Liang, Yujie,Song, Song,Jiao, Ning
-
supporting information
p. 12271 - 12277
(2016/09/28)
-
- Difluorohomologation of ketones
-
A method for the homologation of ketones with the CF2 fragment is described. The reaction involves silylation, room-temperature difluorocyclopropanation of silyl enol ethers, and selective ring opening of cyclopropanes under acidic conditions. The whole three-step sequence is conveniently performed in a one-pot mode.
- Kosobokov, Mikhail D.,Levin, Vitalij V.,Struchkova, Marina I.,Dilman, Alexander D.
-
supporting information
p. 760 - 763
(2015/03/05)
-
- Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene O-H Insertion Reaction
-
Copper- or rhodium-catalyzed reactions of diazocarbonyl compounds with β-hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. Under mild conditions, the single-step process starts as a carbene O-H insertion reaction, but is diverted by an intramolecular aldol reaction. Gone astray: Copper- or rhodium-catalyzed reactions of diazocarbonyl compounds with β-hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. The single-step reaction proceeds under mild conditions, starting as a carbene O-H insertion reaction, but then diverting to an intramolecular aldol reaction.
- Nicolle, Simon M.,Lewis, William,Hayes, Christopher J.,Moody, Christopher J.
-
supporting information
p. 8485 - 8489
(2015/11/27)
-
- Iridium-catalyzed enantioselective allylation of silyl enol ethers derived from ketones and α,β-unsaturated ketones
-
The unified Ir-catalyzed enantioselective allylic substitution reactions of silyl enol ethers derived from ketones and α,β-unsaturated ketones with branched, racemic allylic alcohols are described. This transformation is catalyzed by the Carreira system and proceeds without fluoride, and with high ee and b:l ratio. The synthetic utility of this method was illustrated by the concise enantioselective total synthesis of marine natural products calyxolane A, B and by the assignment of the absolute configuration of calyxolane A.
- Liang, Xiao,Wei, Kun,Yang, Yu-Rong
-
supporting information
p. 17471 - 17474
(2015/12/09)
-
- Asymmetric Catalysis with Ethylene. Synthesis of Functionalized Chiral Enolates
-
Trialkylsilyl enol ethers are versatile intermediates often used as enolate surrogates for the synthesis of carbonyl compounds. Yet there are no reports of broadly applicable, catalytic methods for the synthesis of chiral silyl enol ethers carrying latent functionalities useful for synthetic operations beyond the many possible reactions of the silyl enol ether moiety itself. Here we report a general procedure for highly catalytic (substrate:catalyst ratio up to 1000:1) and enantioselective (92% to 98% major enantiomer) synthesis of such compounds bearing a vinyl group at a chiral carbon at the β-position. The reactions, run under ambient conditions, use trialkylsiloxy-1,3-dienes and ethylene (1 atm) as precursors and readily available (bis-phosphine)-cobalt(II) complexes as catalysts. The silyl enolates can be readily converted into novel enantiopure vinyl triflates, a class of highly versatile cross-coupling reagents, enabling the syntheses of other enantiomerically pure, stereodefined trisubstituted alkene intermediates not easily accessible by current methods. Examples of Kumada, Stille, and Suzuki coupling reactions are illustrated.
- Biswas, Souvagya,Page, Jordan P.,Dewese, Kendra R.,RajanBabu
-
p. 14268 - 14271
(2015/12/01)
-
- Total synthesis of cryptomoscatones D1 and D2: Stereochemical assignment of cryptomoscatone D1
-
The first total synthesis and structural elucidation of cryptomoscatone D1, and a novel synthetic approach for cryptomoscatone D2 were achieved in 30% and 29% overall yield, respectively. The synthesis relied on the use of a key Mukaiyama aldol reaction followed by a diastereoselective carbonyl reduction that allowed the preparation of four cryptomoscatone isomers in a stereochemically divergent manner. Comparison of NMR data and CD curves of the synthetic stereoisomers and natural products confirmed the stereochemical nature of cryptomoscatone D2, and led to establishing the absolute configuration of cryptomoscatone D1.
- Toneto Novaes, Luiz Fernando,Drekener, Roberta Lopes,Avila, Carolina Martins,Pilli, Ronaldo Aloise
-
p. 6467 - 6473
(2015/03/30)
-
- Highly concise and stereoselective total synthesis of (5R,7S)-kurzilactone
-
A highly concise and stereoselective total synthesis of (5R,7S)-kurzilactone (1) was performed by a convergent approach by means of a Jacobsen's hydrolytic kinetic resolution, a Horner-Wadsworth-Emmons reaction for the construction of the α,β-unsaturated
- Mohapatra, Debendra K.,Karthik, Pulluri,Yadav, Jhillu S.
-
experimental part
p. 1226 - 1230
(2012/09/22)
-
- Novel antimalarial 3-azabicyclo[3.2.2]nonane derivatives
-
The present invention relates to novel 3-azabicyclo[3.2.2]nonane derivatives of the general formula (I) or a pharmaceutically acceptable salt thereof wherein R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 are as defined in the specification. The novel 3-azabicyclo[3.2.2]nonane derivatives are particularly useful for treatment and prevention of malaria and trypanosomiasis.
- -
-
-
- Synthetic studies on and mechanistic insight into [W(CO) 5(L)]-catalyzed stereoselective construction of functionalized bicyclo[5.3.0]decane frameworks
-
Stereoselective preparation of a variety of synthetically useful functionalized bicyclo[5.3.0]decane derivatives was achieved by tandem cyclization of 3-siloxy-1,3,9-triene-7-yne derivatives based on the electrophilic activation of alkynes catalyzed by [W(CO)5(L)], The reaction proceeded smoothly under photoirradiation, and various substrates were cyclized to give the corresponding bicyclic compounds with up to four chiral centers stereospecifically. Reactions of siloxydienes with a silyl substituent as an equivalent of a hydroxyl group also proceeded with wide generality to afford silyl-substituted bicyclo[5.3.0]decanes, which were highly useful as synthetic intermediates. Stereochemical studies concerning the silyl enol ether moiety suggested that two types of reaction path way for the formation of seven-membered rings were present. The reaction of (Z)-enol silyl ethers proceeded through Cope rearrangement of cis-divinylcyclopropane intermediates, and that of (E)-enol silyl ethers by 1,4-addition of the dienyl tungsten species at the position δ to the metal atom. In the reactions of siloxydiene derivatives with silyl substituents, all possible diastereomers could be synthesized stereoselectively by changing the geometry of the silyl enol ether and enyne moieties.
- Onizawa, Yuji,Hara, Masahiro,Hashimoto, Takuya,Kusama, Hiroyuki,Iwasawa, Nobuharu
-
supporting information; experimental part
p. 10785 - 10796
(2010/11/19)
-
- A concise and efficient synthesis of (5r,7s)-kurzilactone and its (5s,7r)-enantiomer by the mukaiyama aldol reaction
-
Natural kurzilactone (5R,7S) and its (5S,7R)-enantiomer were synthesized by a convergent approach using a diastereoselective Mukaiyama aldol reaction to construct the anti diol unit. Finally, a ring-closing metathesis reaction led to the target molecule.
- Sabitha, Gowravaram,Gopal, Peddabuddi,Reddy, C. Nagendra,Yadav, Jhillu S.
-
scheme or table
p. 3301 - 3304
(2010/04/03)
-
- Efficient control of π-alkyne and vinylidene complex pathways for the W(CO)5(L)-catalyzed synthesis of two types of nitrogen-containing bicyclic compounds
-
When ω-acetylenic dienol silyl ethers containing NMs part in the tether were treated with a catalytic amount of W(CO)6 under photoirradiation, 2-azabicyclo[3.3.0]octanes were obtained in good yield via π-alkyne complexes. On the other hand, treatment of the same substrates with a catalytic amount of W(CO)6 in the presence of n-Bu3N under the same reaction conditions gave 3-azabicyclo[3.3.0]octanes in good yield exclusively via vinylidene complexes. Thus, the π-alkyne and vinylidene complex pathways are easily controlled by using a catalytic amount of W(CO)5(L) and an amine. Copyright
- Onizawa, Yuji,Kusama, Hiroyuki,Iwasawa, Nobuharu
-
p. 802 - 803
(2008/09/20)
-
- Sc(OTf)3-catalyzed smooth tandem [3+2] cycloaddition/ring opening of donor-acceptor cyclopropane 1,1-diesters with enol silyl ethers
-
Catalyzed by Lewis acids, donor-acceptor cyclopropane 1,1-diesters reacted with enol silyl ethers to afford 1,6-dicarbonyl compounds in moderate to excellent yields. This supplied a mild carbon-carbon bond-forming method from the ring opening of cyclopropanes. A smooth tandem [3+2] cycloaddition/ring opening process has been clearly proved by an independent experiment.
- Fang, Jie,Ren, Jun,Wang, Zhongwen
-
supporting information; body text
p. 6659 - 6662
(2009/04/07)
-
- W(CO)5(L)-catalyzed tandem intramolecular cyclopropanation/cope rearrangement for the stereoselective construction of bicyclo[5.3.0]decane framework
-
Utilizing the biscarbene character of electrophilically activated alkynes, a novel tandem intramolecular cyclopropanation/Cope rearrangement of 3-siloxy-1,3,9-trien-7-ynes catalyzed by W(CO)5(L) for the stereoselective construction of bicyclo[5.3.0]decane framework is achieved. When 3-siloxy-1,3,9-trien-7-ynes were treated with a catalytic amount of W(CO)6 under photoirradiation, bicyclo[5.3.0]decanes were obtained in good yield stereoselectively. In this reaction, the Cope rearrangement of the divinylcyclopropane intermediates, generated by the intramolecular cyclopropanation of 3-siloxy-1,3,9-trien-7-ynes based on the W(CO)5(L)-catalyzed electrophilic activation of alkynes, occurs to give synthetically useful functionalized bicyclo[5.3.0]decane derivatives stereoselectively. Copyright
- Kusama, Hiroyuki,Onizawa, Yuji,Iwasawa, Nobuharu
-
p. 16500 - 16501
(2007/10/03)
-
- Versatile diastereoselectivity in formal [3,3]-sigmatropic shifts of substituted 1-alkenyl-3-alkylidenecyclobutanols and their silyl ethers
-
A new method for the preparation of highly substituted cyclohexenones is reported. [2 + 2] Cycloaddition of 2-silyloxydienes with allenecarboxylate affords the 1-alkenyl-3-alkylidenecyclobutanol silyl ethers. Thermolysis of these compounds affords the met
- Jung, Michael E.,Nishimura, Nobuko,Novack, Aaron R.
-
p. 11206 - 11207
(2007/10/03)
-
- Formation of 3,4-dimethyl-2-pyrones from allene carboxylates and 2-silyloxydienes via 3-carboethoxyethylidene cyclobutanols
-
The 3-carboethoxyethylidene cyclobutanols 4 are prepared in two steps via [2+2] cycloaddition of the 2-silyloxydienes 1 and the allene carboxylate 2 followed by acidic hydrolysis. Treatment of these cyclobutanols 4 with various bases affords good yields o
- Jung, Michael E.,Novack, Aaron R.
-
p. 8237 - 8240
(2007/10/03)
-
- Rhenium(I)-catalyzed intramolecular geminal carbofunctionalization of alkynes: Tandem cyclization of ω-acetylenic dienol silyl ethers
-
(Chemical Equation Presented) Bicycle production: The low-valent rhenium complex [ReCl(CO)5] catalyzes a tandem intramolecular cyclization reaction of ω-acetylenic dienol silyl ethers. The alkyne undergoes a geminal carbofunctionalization in the presence of 0.5-3.0 mol % [ReCl(CO) 5] under photoirradiation to give bicyclic enol silyl ethers in high yields (see scheme, TIPS = triisopropylsilyl).
- Kusama, Hiroyuki,Yamabe, Hokuto,Onizawa, Yuji,Hoshino, Takahiko,Iwasawa, Nobuharu
-
p. 468 - 470
(2007/10/03)
-
- Diastereoselective synthesis of five- and seven-membered rings by [2+2+1], [3+2], [3+2+2], and [4+3] carbocyclization reactions of β-substituted (alkenyl)(methoxy)carbene complexes with methyl ketone lithium enolates
-
β-Substituted alkenylcarbene complexes react with methyl ketone lithium etiolates to give different carbocyclization products depending on the structure of the lithium enolate, on the metal of the carbene complex, and on the reaction media. Thus, the reac
- Barluenga, Jose,Alonso, Jorge,Fananas, Francisco J.
-
p. 4995 - 5006
(2007/10/03)
-
- A general one-pot synthesis of vinyl-thiiranes and conjugated dienes
-
The first general synthesis of vinyl-thiiranes 7 and an effiecient preparation of conjugated dienes 8 and 9 is presented. Methodology described for the preparation of these compounds is based on the corresponding readily available thiophosphates 1 and selenophosphates 2.
- Maciagiewicz,Dybowski,Skowronska
-
p. 515 - 523
(2007/10/03)
-
- Total synthesis of (-)-hennoxazole A
-
The antiviral marine natural product (-)-hennoxazole A was efficiently synthesized by a convergent approach. The stereoselective synthesis of the functionalized tetrahydropyran fragment was accomplished by the Mukaiyama aldol reaction, chelation-controlle
- Yokokawa, Fumiaki,Asano, Toshinobu,Shioiri, Takayuki
-
p. 6311 - 6327
(2007/10/03)
-
- Total synthesis of the antiviral marine natural product (-)-hennoxazole A.
-
[structure:see text] The marine natural product hennoxazole A was synthesized by a convergent approach. The diastereoselective Mukaiyama aldol reaction with beta-alkoxy aldehyde was used to construct the tetrahydropyran segment, and the preparation of the
- Yokokawa,Asano,Shioiri
-
p. 4169 - 4172
(2007/10/03)
-
- A general one-pot synthesis of vinyl-thiiranes and conjugated dienes
-
The first general synthesis of vinyl-thiiranes 5 and an efficient preparation of conjugated dienes 6 and 7 based on thio, and selenophosphates is described.
- Maciagiewicz,Dybowski,Skowronska
-
p. 3791 - 3794
(2007/10/03)
-
- Two-Step Synthesis of (γ,γ-Difluoroallyl)carbonyl Compounds via Addition of 1,1,2-Trichloro-2,2-difluoroethyl Radical to Silyl Enol Ethers Followed by Reductive Dechlorination
-
Ru(II)- or Cu(I)-induced radical reaction of CF2ClCCl2. radical (2), regioselectively derived from CF2ClCCl3, to trimethylsilyl enol ethers and a ketene silyl acetal yields (β,β,γ-trichloro-γ,γ-difluoropropyl)carbonyl compounds 5 as the intermediates.Spontaneous dehydrochlorination affords carbonyl compounds 4.Reductive dechlorination of 4 with zinc gave γ,γ-difluoroallyl ketones 7a-e and an ester 7f.In some cases, Ni(0)-catalyzed reduction with zinc is superior than the simple hydrodechlorination.
- Okano, Takashi,Shimizu, Toshihiro,Sumida, Koji,Eguchi, Shoji
-
p. 5163 - 5166
(2007/10/02)
-
- Enolate Ions, II. - Convenient Synthesis of 3,4-Dihydro-2,4-dioxo-2H-pyrans and 2-Pyrones. - Enolate Ions as Synthetic Equivalents of 1,3-Dianions. - Crystal and Molecular Structure of Ethyl 6-Ethoxy-3,4-dihydro-3,3-dimethyl-2,4-dioxo-2H-pyran-5-carboxyla
-
Reaction of dimethylmalonyl chloride (6a) or cyclic 1,1-dicarbonyl dichlorides 6b-d with two equivalents of lithium enolates 7, 22, and silyl enol ethers 8, respectively, yields 3,4-dihydro-2,4-dioxo-2H-pyrans 10, 24, or spiro compounds 11-13, 25-27.The s
- Saalfrank, Rolf W.,Guendel, Juergen,Rossmann, Guenther,Hanek, Martin,Rost, Walter,et al.
-
p. 1175 - 1183
(2007/10/02)
-
- AN EFFICIENT SYMTHESIS OF SILYL ENOL ETHERS FROM α,β-UNSATURATED ALDEHYDES AND KETONES
-
α,β-Unsaturated aldehydes and ketones when reacted with NaBr-Me3SiCl-Et3N in DMF at ambient temperature, yield silyl dienol ethers in high yields.
- Iqbal, Javed,Khan, M. Amin
-
p. 515 - 522
(2007/10/02)
-
- A NEW PRACTICAL SYNTHESIS OF SILYL ENOL ETHERS. II. FROM α,β-UNSATURATED ALDEHYDES AND KETONES
-
In acetonitrile as the solvent and in the presence of a tertiary amine the trimethylchlorosilane/sodium iodide (trimethyliodosilane "in situ") reagent provides the corresponding siloxy dienes when reacted with α,β-unsaturated series.These reactions occurs
- Cazeau, P.,Duboudin, F.,Moulines, F.,Babot, O.,Dunogues, J.
-
p. 2089 - 2100
(2007/10/02)
-