- Asymmetric Catalytic Epoxidation of Terminal Enones for the Synthesis of Triazole Antifungal Agents
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An enantioselective epoxidation of α-substituted vinyl ketones was realized to construct the key epoxide intermediates for the synthesis of various triazole antifungal agents. The reaction proceeded efficiently in high yields with good enantioselectivities by employing a chiral N,N′-dioxide/ScIII complex as the chiral catalyst and 35% aq. H2O2 as the oxidant. It enabled the facile transformation for optically active isavuconazole, efinaconazole, and other potential antifungal agents.
- Feng, Xiaoming,He, Qianwen,Liu, Xiaohua,Zhang, Dong,Zhang, Fengcai
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supporting information
p. 6961 - 6966
(2021/09/11)
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- Formal Enone α-Arylation via I(III)-Mediated Aryl Migration/Elimination
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A formal enone α-arylation is described. This metal-free transformation relies on the I(III)-mediated skeletal reorganization of silyl enol ethers and features mild conditions, good yields, and high stereoselectivities for β-substituted enones.
- Martins, Bruna S.,Kaiser, Daniel,Bauer, Adriano,Tiefenbrunner, Irmgard,Maulide, Nuno
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supporting information
p. 2094 - 2098
(2021/04/05)
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- Bromomethyl Silicate: A Robust Methylene Transfer Reagent for Radical-Polar Crossover Cyclopropanation of Alkenes
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A general protocol for visible-light-induced cyclopropanation of alkenes was developed with bromomethyl silicate as a methylene transfer reagent, offering a robust tool for accessing highly valuable cyclopropanes. In addition to α-aryl or methyl-substituted Michael acceptors and styrene derivatives, the unactivated 1,1-dialkyl ethylenes were also shown to be viable substrates. Apart from realizing the cyclopropanation of terminal alkenes, the methyl transfer reaction has been further demonstrated to be amenable to the internal olefins. The photocatalytic cyclopropanation of 1,3-bis(1-arylethenyl)benzenes was also achieved, giving polycyclopropane derivatives in excellent yields. With late-stage cyclopropanation as the key strategy, the synthetic utility of this transformation was also demonstrated by the total synthesis of LG100268.
- Luo, Wenping,Fang, Yewen,Zhang, Li,Xu, Tianhang,Liu, Yongjun,Li, Yan,Jin, Xiaoping,Bao, Jiakan,Wu, Xiaodong,Zhang, Zongyong
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p. 1778 - 1781
(2020/03/11)
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- METHOD FOR PREPARING CHLORINATED KETONE COMPOUNDS
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PROBLEM TO BE SOLVED: To provide a method for efficiently producing a α-methylene ketone compound, which is widely found in natural products and is known as a biologically active substance, by a method in which an α, α-disubstituted allyl alcohol compound is used as a raw material, and an expensive oxidizing agent such as a heavy metal system is not used and an environmental load is reduced. SOLUTION: An α, α-disubstituted allyl alcohol compound represented by general formula (1) (wherein R1 and R2 each represents an alkyl group, an aromatic hydrocarbon group, or an alicyclic hydrocarbon group; alternatively, R1 and R2 may form together an aliphatic hydrocarbon ring), is oxidized in the presence of tetraalkylammonium hypochlorite to give a chlorinated ketone compound. This chlorinated ketone compound can be made into an α-methylene ketone compound by dehydrochlorination in the presence of a base. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0050-0053
(2021/02/04)
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- Enantioselective Bromolactonization of Trisubstituted Olefinic Acids Catalyzed by Chiral Pyridyl Phosphoramides
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Enantioselective bromolactonization of trisubstituted olefinic acids producing synthetically useful chiral lactones with two contiguous asymmetric centers has remained mainly unexplored except for the 6-exo cyclization mode. In this work, the 5-exo- and 6
- Nishikawa, Yasuhiro,Hamamoto, Yuhta,Satoh, Rika,Akada, Naho,Kajita, Shuhei,Nomoto, Marina,Miyata, Megumi,Nakamura, Madoka,Matsubara, Chinatsu,Hara, Osamu
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supporting information
p. 18880 - 18885
(2018/12/04)
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- Enantioselective synthesis of β-substituted chiral allylic amines: Via Rh-catalyzed asymmetric hydrogenation
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An asymmetric mono-hydrogenation of 2-acetamido-1,3-dienes catalyzed by a Rh-DuanPhos complex has been developed. This approach provides easy access to chiral allylic amines with excellent enantioselectivities and high regioselectivities. The products are valuable chiral building blocks for pharmaceuticals.
- Wang, Qingli,Gao, Wenchao,Lv, Hui,Zhang, Xumu
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p. 11850 - 11853
(2016/10/07)
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- Ene di- and trimerization of 1-methyl-2-phenylcyclopropene
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1,2-Disubstituted cyclopropene, 1-methyl-2-phenylcyclopropene (18), was generated by bromo-lithium exchange of 1-bromo-2-phenylcyclopropene followed by treatment with methyl iodide. Compound 18 was oxidized by oxygen to give the α,β-unsaturated carbonyl product 25 and diketone 27 and the tautomeric, β-hydroxyl-α,β-unsaturated ketone 28. However, compound 28 reacted further with the cyclopropene 18 in a retro-Claisen-like reaction to generate adduct 26. Furthermore, compound 18 underwent ene dimerization in neat condition to form the endo-dimer 40 and exo-dimer 41 followed by oxidization with oxygen to give aldehyde 39. It is noteworthy that the endo-dimer 40 and exo-dimer 41 could be trapped with thiophenol to give adduct 42 and 43. In addition, the ene reaction of exo-dimer 41 with monomer 18 gave an exo-exo ene trimer 46 through an exo-transition state which was also trapped by thiophenol to give adducts 44 and 45.
- Lin, Hung-Chun,Tsai, Ru-Ting,Wu, Hsiao-Pin,Lee, Hsin-Yi,Lee, Gon-Ann
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p. 184 - 191
(2015/12/23)
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- Expedient Access to 2,3-Dihydropyridines from Unsaturated Oximes by Rh(III)-Catalyzed C-H Activation
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α,β-Unsaturated oxime pivalates are proposed to undergo reversible C(sp2)-H insertion with cationic Rh(III) complexes to furnish five-membered metallacycles. In the presence of 1,1-disubstituted olefins, these species participate in irreversible migratory insertion to give, after reductive elimination, 2,3-dihydropyridine products in good yields. Catalytic hydrogenation can then be used to convert these molecules into piperidines, which are important structural components of numerous pharmaceuticals.
- Romanov-Michailidis, Fedor,Sedillo, Kassandra F.,Neely, Jamie M.,Rovis, Tomislav
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supporting information
p. 8892 - 8895
(2015/08/03)
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- Nonenzymatic kinetic resolution of α-aryl substituted allylic alcohols catalyzed by acyl transfer catalyst Np-PIQ
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Chiral α-aryl substituted allylic alcohols are important versatile synthetic intermediates. We report here an effective nonenzymatic kinetic resolution of racemic α-aryl substituted allylic alcohols by introducing different aryl groups with acyl transfer
- Jiang, Shan-Shan,Gu, Bo-Qi,Zhu, Ming-Yu,Yu, Xingxin,Deng, Wei-Ping
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p. 1187 - 1191
(2015/02/19)
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- Metal-free, one-pot, sequential protocol for transforming ,-epoxy ketones to -hydroxy ketones and -methylene ketones
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A new sequential, one-pot protocol for transforming 1,3-disubstituted 2,3-epoxy ketones to β;-hydroxy ketones and α-methylene ketones has been developed. Reaction of epoxy ketones with boron trifluoride etherate (BF3·OEt2) generates the cationic intermediates by regioselective epoxide ring opening and an acyl shift. Then, a treatment of these cations with 2-aryl-1,3-dimethylbenzimidazolines (DMBIH) results in formation of 1,2-disubstituted 3-hydroxy ketones. DMBIH serves as a hydride donor in the second step of this process. Finally, the β;-hydroxy ketones can be converted to 1,2-disubstituted 2-methylene ketones by treatment with methanesulfonic acid or a combination of methanesulfonyl chloride and triethylamine. Importantly, the sequential steps involved in formation of the α-methylene ketone products can be carried out in one pot.
- Hasegawa, Eietsu,Arai, Saki,Tayama, Eiji,Iwamoto, Hajime
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p. 1593 - 1600
(2015/02/19)
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- Remote stereocontrol mediated by a sulfinyl group: Synthesis of allylic alcohols via chemoselective and diastereoselective reduction of γ-methylene δ-ketosulfoxides
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The efficiency of the sulfinyl group as a remote controller of the chemoselectivity and diastereoselectivity of the reduction of α,β-unsaturated α-[2-(p-tolylsulfinyl)phenyl] substituted ketones 1 has been demonstrated in reactions carried out under NaBH
- Ruano, Jose L. Garcia,Fernandez-Ibanez, M. Angeles,Fernandez-Salas, Jose A.,Maestro, M. Carmen,Marquez-Lopez, Pablo,Rodriguez-Fernandez, M. Mercedes
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supporting information; scheme or table
p. 1200 - 1204
(2009/07/18)
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- SULFONYLPYRAZOLE AND SULFONYLPYRAZOLINE CARBOXAMIDINE DERIVATIVES AS 5-HT6 ANTAGONISTS
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This invention concerns sulfonylpyrazoline carboxamidine derivatives as antagonists of 5-HT6 receptors, to methods for the preparation of these compounds and to novel intermediates useful for their synthesis. The invention also relates to the uses of such compounds and compositions, particularly their use in administering them to patients to achieve a therapeutic effect in Parkinson's disease, Huntington's chorea, schizophrenia, anxiety, depression, manic depression, psychoses, epilepsy, obsessive compulsive disorders, mood disorders, migraine, Alzheimer's disease, age related cognitive decline, mild cognitive impairment, sleep disorders, eating disorders, anorexia, bulimia, binge eating disorders, panic attacks, akathisia, attention deficit hyperactivity disorder, attention deficit disorder, withdrawal from abuse of cocaine, ethanol, nicotine or benzodiazepines, pain, disorders associated with spinal trauma or head injury, hydrocephalus, functional bowel disorder, Irritable Bowel Syndrome, obesity and type-2 diabetes. The compounds have the general formula (1), wherein the symbols have the meanings given in the description.
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Page/Page column 29
(2008/06/13)
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- An efficient synthesis of α-branched enones
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A new method for preparing α-branched enones from carboxylic acid derivatives is reported. The procedure commenced by the reaction of N,O-dimethylamides with a masked acyl anion equivalent, followed by the addition of (trimethylsilyl-methyl)cerium dichloride to give intermediates that undergo Lewis acid mediated olefination to produce enol ethers that are then hydrolyzed to afford simple α-branched enones in high overall yields.
- Kummer, David A.,Brenneman, Jehrod B.,Martin, Stephen F.
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p. 1431 - 1433
(2007/10/03)
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- Preparation of α-methylene ketones by direct methylene transfer
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Four methods for the preparation of α-methylene ketones by direct methylene transfer are presented. The procedures were optimized in order to obtain high yields.
- Rodrigues, J. Augusto R.,Siqueira-Filho, Ezequias P.,De Mancilha, Moacir,Moran, Paulo J. S.
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p. 331 - 340
(2007/10/03)
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- Baker's yeast reduction of α-methyleneketones
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The bioreduction of α-methyleneketones, R1C(=O)C(=CH2)R2 (R1 = Me, Et, Pr, iso-Bu, Ph, CH2CH2Ph; R2 = Cl, Me, Et, n-Pr, iso-Pr, n-Bu, n-C6H13, Ph, CH2Ph), was mediated by baker's yeast (Saccharomyces cerevisiae) to obtain the corresponding α-methylketones. The R1 and R2 groups had a significant influence on the rate and enantioselectivity of the reductions. The rate of C=C bond reduction was higher than that of C=O bond reduction. Only α-methyleneketones having R1 = Me yielded α-methylketones in high enantioselectivity with e.e.s of 88-99%.
- Siqueira Filho, Ezequias P.,Rodrigues, J.Augusto R.,Moran, Paulo J.S.
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p. 847 - 852
(2007/10/03)
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- Aqueous DMF - Potassium carbonate as a substitute for thallium and silver additives in the palladium-catalyzed conversion of aryl bromides to acetyl arenes
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Highly selective palladium-catalyzed internal α-arylations of alkyl vinyl ethers with aryl and heteroaryl bromides were conveniently conducted in aqueous DMF with potassium carbonate as base and with DPPP as bidentate ligand. The corresponding acetyl arene products were, after hydrolysis, isolated in good to excellent yields. This Heck reaction procedure does not require toxic thallium or expensive silver salt additives, is promoted by water, and is suggested to proceed via charged organopalladium intermediates. Single-mode microwave irradiation was utilized in one example to shorten the reaction time.
- Vallin,Larhed,Hallberg
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p. 4340 - 4343
(2007/10/03)
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- REACTION OF ALKYL- AND PHENYL-SUBSTITUTED 5-AMINOMETHYL-2(5H)-FURANONES WITH DIMETHYLAMINE
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The product from the addition of dimethylamine to 5-dimethylaminomethyl-5-propyl-2(5H)-furanone was obtained.When heated in the presence of dimethylamine, the analogs containing a substituent at the β position to the carbonyl group are transformed into 3-
- Tyvorskii, V. I.,Kukharev, A. S.
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p. 840 - 843
(2007/10/02)
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- Asymmetric Reduction of Carbon-Carbon Double Bonds of Conjugated Enones with Fermenting Bakers' yeast
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Bakers' yeast reduction of α-substituted or β,β-disubstituted α,β-unsaturated ketones gave saturated chiral ketones with excellent optical purity, while the β,β-disubstituted derivatives remains intact.
- Sakai, Takashi,Matsumoto, Syuji,Hidaka, Syukou,Imajo, Norihisa,Tsuboi, Sadao,Utaka, Masanori
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p. 3473 - 3475
(2007/10/02)
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- SYNTHESIS OF β- AND γ-HYDROXY SULFONES BY REGIOSELECTIVE OPENING OF β,γ-EPOXY SULFONES
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β,γ-Epoxy sulfones 1 derived from allylic sulfones react regioselectively with organomagnesium compounds in the presence or not of catalytic amounts of copper(I) bromide to afford β-hydroxy sulfones 2 or γ-tosylated allylic alcoholates 5 respectively.The Michael type addition of Grignard reagents to intermediates 5 in the presence of catalytic amount of copper(I) bromide yields γ-hydroxy sulfones 6.The PCC oxidation of β- and γ-hydroxy sulfones give β- and γ-oxo sulfones 10 and 11 respectively.In the case of γ-oxo-sulfones their treatment with DBU affords α-substituted, α, β- unsaturated carbonyl compounds.
- Najera, Carmen,Sansano, Jose Miguel
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p. 3993 - 4002
(2007/10/02)
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- A Convenient One-flask Synthesis of α-Methylenealdehydes from Primary Alcohols
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A convenient one-flask synthesis of α-methylenealdehydes from primary alcohols has been established.
- Takano, Seiichi,Inomata, Kohei,Samizu, Kiyohiro,Tomita, Shun'ichi,Yanase, Masashi,et al.
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p. 1283 - 1284
(2007/10/02)
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- USE OF MOIST SILICA GEL FOR OBTAINING α-ETHYLENIC CARBONYL COMPOUNDS FROM Β-ALKYLTHIO OR β-PHENYLTHIO ALLYLIC ALCOHOLS.
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The β-alkylthio and β-phenylthio α-ethylenic aldehydes 2, (Z)-6, (E)-6 and 9 were obtained from the corresponding β-chloro α-ethylenic aldehydes, and the α-phenylthiometylidene ketones (Z)-13 and (E)-13 by Peterson reaction with α,α-dimethoxycyclohexanone followed by deacetalization.Reduction (NaBH4) or addition of organolithium compounds led to allylic alcohols which gave α-ethylenic carbonyl compounds with removal of thiol or thiophenol after treatment by moist acidic silica gel with or without mercuric chloride.The method also worked for oxygenated compounds 21, 22.
- Pellet, Michele,Huet, Francois
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p. 4463 - 4468
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF 1H-1,2,4-TRIAZOL-1-YL-PROPAN-3-ONE DERIVATIVES BY MODIFIED MANNICH REACTION
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1H-1,2,4-Triazol-yl-propan-3-ones were synthesized regioselectively using a modified Mannich reaction.Reactions of enones and Mannich bases with imidazole are also described.
- Takahashi, Kimio,Shimizu, Sumio,Ogata, Masaru
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p. 809 - 816
(2007/10/02)
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- Palladium-Catalyzed Denitro-Sulfonylation and Amination of β,γ-Epoxy Nitro Compounds
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β-Alkyl-β,γ-epoxy nitro compounds undergo the weak base catalyzed conversion to γ-hydroxy-α-nitro olefins followed by isomerization of the resulting double bond and the subsequent Pd(0)-catalyzed allylic substitution of the hydroxy allylic nitro intermedi
- Tamura, Rui,Kato, Masami,Saegusa, Koji,Oda, Daihei,Egawa, Takafumi,Yamamoto, Tamotsu
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p. 1640 - 1642
(2007/10/02)
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- Destabilized Carbenium Ions. Secondary and Tertiary α-Acetylbenzyl Cations and α-Benzoylbenzyl Cations
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The secondary α-acetylbenzyl and α-benzoylbenzyl cations, as well as their tertiary analogues, have been generated in a mass spectrometer by electron impact induced fragmentation of the corresponding α-bromoketones.These ions belong to the interesting family of destabilized α-acylcarbenium ions.While primary α-acylcarbenium ions appear to be unstable, the secondary and tertiary ions exhibit the usual behaviour of stable entities in a potential energy well.This can be attributed to a 'push-pull' substitution at the carbenium centre by an electron-releasing phenyl group and an electron-withdrawing acyl substituent.The characteristic unimolecular reaction of the metastable secondary and tertiary α-acylbenzyl cations is the elimination of CO by a rearrangement reaction involving a 1,2-shift of a methyl group and a phenyl group, respectively.The loss of CO is accompanied by a very large kinetic energy release, which gives rise to a broad and dish-topped peaks for this process in the mass-analysed ion kinetic energy spectra of the corresponding ions.This behaviour is attributed to the rigid critical configuration of a corner-protonated cyclopropanone derivative and a bridged phenonium ion derivative, respectively, for this reaction.For the tertiary α-acetyl-α-methylbenzyl cations, it has been shown by deuterium labelling and by comparison of collisional activation spectra that these ions equilibrate prior to decomposition with their 'protomer' derivatives formed by proton migration from the α-methyl substituent to the carbonyl group and to the benzene ring.
- Dommroese, Anne-Marie,Gruetzmacher, Hans-Friedrich
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p. 437 - 443
(2007/10/02)
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- Monoozonolyses of Acyclic Conjugated Dienes
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Monoozonolyses of isoprene (1a), 2-methyl-3-phenyl-1,3-butadiene (1b), 2,3-diphenyl-1,3-butadiene (25), and 2,3,4,5-tetramethyl-2,4-hexadiene (34) have been examined in pentane and in methanol.The dienes 1a, b and 25 afforded all possible α,β-unsaturated monoozonides and α,β-unsaturated methoxy hydroperoxides, respectively, whereas diene 34 gave no ozonide and no α,β-unsaturated methoxy hydroperoxide.From the dienens 25 and 34, the corresponding monoepoxides have been formed additionally.The results allow some conclusions concerning the regioselectivity of ozone attack at the unsymmetrically substituted dienes 1a, b as well as concerning the cleavage directions of primary ozonides.
- Griesbaum, Karl,Zwick, Gerhard
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p. 3041 - 3057
(2007/10/02)
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- Carbon-Carbon Bond Formation by the Use of Chloroiodomethane as a C1 Unit. III. A Convenient Synthesis of the Mannich Base from Enol Silyl Ether by a Combination of Chloroiodomethane and N,N,N',N'-Tetramethylmethanediamine
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The Mannich dimethylaminomethylation of carbonyl compounds is conveniently carried out via enol trimethylsilyl ethers by a combination of chloroiodomethane (CH2ClI) and N,N,N',N'-tetramethylmethanediamine (TMMD) in DMSO as the solvent at ambient temperatute.The mechanism of the transformation is discussed on the basis of product analysis and 1H NMR spectral studies.The reagent system CH2ClI/TMMD also provides a convenient route to the Eschenmoser's salt ().
- Miyano, Sotaro,Hokari, Hiroshi,Hashimoto, Harukichi
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p. 534 - 539
(2007/10/02)
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