- Synthesis of Cyclopentenones through Rhodium-Catalyzed C-H Annulation of Acrylic Acids with Formaldehyde and Malonates
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An efficient rhodium-catalyzed protocol for the synthesis of cyclopentenones based on a three-component reaction of acrylic acids, formaldehyde, and malonates via vinylic C-H activation is reported. Exploratory studies showed that 5-alkylation of as-prepared cyclopentenones could be realized smoothly by the treatment of a variety of alkyl halides with a Na2CO3/MeOH solution. Excess formaldehyde and malonate led to a multicomponent reaction that afforded the multisubstituted cyclopentenones through a Michael addition.
- Yu, Shuling,Hong, Chao,Liu, Zhanxiang,Zhang, Yuhong
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supporting information
p. 5054 - 5059
(2021/07/20)
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- Rhodium Porphyrin Catalyzed Regioselective Transfer Hydrogenolysis of C-C σ-Bonds in Cyclopropanes with iPrOH
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A new rhodium porphyrin catalyzed regioselective transfer hydrogenolysis of both activated and unactivated cyclopropanes employing iPrOH as the hydrogen source was discovered. The reaction mechanism for the C-C σ-bond activation of cyclopropanes was identified through an initial radical substitution with rhodium(II) metalloporphyrin radical to give a rhodium porphyrin alkyl, followed by hydrogenolysis with iPrOH to give the corresponding acyclic alkanes and regenerate rhodium(II) metalloporphyrin radical.
- Chen, Chen,Feng, Shiyu,Chan, Kin Shing
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p. 2582 - 2589
(2019/07/02)
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- Nano-K2CO3: Preparation, characterization and evaluation of reactive activities
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A novel base, nano-K2CO3, was easily prepared by ultrafine wet milling. The surface properties and the reactive activities of nano-K2CO3 were characterized. It was found that such a base showed higher basicity than normal K2CO3 and could replace sodium (or potassium) alkoxide to carry out monoalkylation and oximation of active methylene compounds. The nano-K2CO3 could be regenarated and reused 10 times without loss of its reactive activity.
- Li, Jun-Zhang,Fan, Shi-Ming,Sun, Xuan-Fei,Liu, Shouxin
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p. 1865 - 1869
(2016/01/20)
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- Bifunctional Iminophosphorane Catalyzed Enantioselective Sulfa-Michael Addition to Unactivated α-Substituted Acrylate Esters
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The highly enantioselective sulfa-Michael addition of alkyl thiols to unactivated α-substituted acrylate esters catalyzed by a bifunctional iminophosphorane organocatalyst under mild conditions is described. The strong Br?nsted basicity of the iminophosphorane moiety of the catalyst provides the necessary activation of the alkyl thiol pro-nucleophile, while the two tert-leucine residues flanking a central thiourea hydrogen-bond donor facilitate high enantiofacial selectivity in the protonation of the transient enolate intermediate. The reaction is broad in scope with respect to the alkyl thiol, the ester moiety, and the α-substituent of the α,β-unsaturated ester, affords sulfa-Michael adducts in excellent yields (up to >99%) and enantioselectivities (up to 96% ee), and is amenable to decagram scale-up using catalyst loadings as low as 0.05 mol %.
- Farley, Alistair J. M.,Sandford, Christopher,Dixon, Darren J.
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supporting information
p. 15992 - 15995
(2016/01/15)
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- Copper(II) triflate catalyzed amination and aziridination of 2-Alkyl substituted 1,3-dicarbonyl compounds
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A method to prepare α-acyl-β-amino acid and 2,2-diacyl aziridine derivatives efficiently from Cu(OTf)2 + 1,10-phenanthroline (1,10-phen)-catalyzed amination and aziridination of 2-alkyl substituted 1,3-dicarbonyl compounds with PhI=NTs is described. By taking advantage of the orthogonal modes of reactivity of the substrate through slight modification of the reaction conditions, a divergence in product selectivity was observed. In the presence of 1.2 equiv of the iminoiodane, amination of the allylic C-H bond of the enolic form of the substrate, formed in situ through coordination to the Lewis acidic metal catalyst, was found to selectively occur and give the β-aminated adduct. On the other hand, increasing the amount of the nitrogen source from 1.2 to 2-3 equiv was discovered to result in preferential formal aziridination of the C-C bond of the 2-alkyl substituent of the starting material and formation of the aziridine product.
- Ton, Thi My Uyen,Tejo, Ciputra,Tiong, Diane Ling Ying,Chan, Philip Wai Hong
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experimental part
p. 7344 - 7350
(2012/06/16)
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- Palladium-catalyzed cycloisomerizations of (Z)-1-iodo-1,6-dienes: Iodine atom transfer and mechanistic insight to alkyl iodide reductive elimination
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A palladium-catalyzed iodine atom transfer cycloisomerization of (Z)-1-iodo-1,6-diene has been developed, which provides a facile method to construct six-memebered heterocycles bearing an alkyl iodide group. The ligand screening shows that both the type and the quantity of ligand impose significant influences on this transformation, and the combination of 30 mol % 1,1′-bis(diphenylphosphino)ferrocene (DPPF) and 10 mol % Pd(OAc) 2 is the optimal choice. The catalytic cycle, consisting of oxidative addition of Pd(0) to vinyl iodide, intramolecular alkene insertion, and alkyl iodide reductive elimination, has been proposed and eventually supported by convincing evidence from a series of control experiments. More importantly, these control experiments disclose some features of the event of alkyl iodide reductive elimination: (1) this reductive elimination is proved to be a stereospecific process; and (2) both alkyl iodide oxidative addition and reductive elimination are not effected by a TEMPO additive. Besides its ability to undergo oxidative addition, the catalyst (palladium + DPPF) could also promote a radical transfer process. The findings described in this paper will be helpful for further development of the metal-catalyzed formation of a carbon-halide bond.
- Liu, Hui,Li, Chaolong,Qiu, Dong,Tong, Xiaofeng
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supporting information; experimental part
p. 6187 - 6193
(2011/06/22)
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- Pheromones and analogs from Neozeleboria wasps and the orchids that seduce them: a versatile synthesis of 2,5-dialkylated 1,3-cyclohexanediones
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Chiloglottone, a wasp pheromone and attractant of sexually deceptive Chiloglottis orchids, and several structural analogs were synthesized. The synthetic approach is facile, high yielding and versatile, enabling rapid divergence to generate dialkylated analogs of chiloglottone. The key transformation was an organocadmium-mediated desymmetrization of glutaric anhydride derivatives. This library of synthetic 2,5-dialkylated 1,3-cyclohexanediones may assist in future identification of natural products in further species.
- Poldy, Jacqueline,Peakall, Rod,Barrow, Russell A.
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p. 2446 - 2449
(2008/09/20)
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- Toward a total synthesis of the novel polyketide natural product spiculoic acid A
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(Chemical Equation Presented) An enantioselective approach toward the recently isolated marine natural product, spiculoic acid A, conceptualized along the proposed biogenetic hypothesis, involving an intramolecular Diels-Alder reaction as the pivotal step
- Mehta, Goverdhan,Kundu, Uday Kumar
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p. 5569 - 5572
(2007/10/03)
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- Pyran-2-ones and 5,6-dihydropyran-2-ones useful for treating hyperplasia and other diseases
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Certain 2H-pyran-2-ones are useful for treating benign prostatic hypertrophy or hyperplasia, prostatic cancer, alopecia, hirsutism, acne vulgaris and seborrhea.
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Page 36, 158
(2010/02/05)
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- Applications of diethoxymethane as a versatile process solvent and unique reagent in organic synthesis
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Diethoxymethane (DEM) has recently become available in commercial quantities. It has unique properties and is useful in a variety of applications in organic synthesis. It is low boiling (88 °C), azeotropes with water, and has a very low affinity for water. It is stable under basic conditions and as manufactured does not require drying for use as a solvent, even for organometallic reactions. DEM is useful as a process solvent especially for sodium hydride reactions, organolithium chemistry, copper-catalyzed conjugate additions, and phase-transfer reactions. As such, DEM is a potential replacement for tetrahydrofuran (THF), dichloromethane (CH2Cl2), glyme (1,2-dimethoxyethane), and methylal (1,1-dimethoxymethane). DEM is also useful as an ethoxymethylating agent, a formaldehyde equivalent, and a carbonylation substrate. Due to these unique properties and applications, DEM has exciting potential for widespread use both as a reagent and especially as a preferred solvent.
- Boaz, Neil W.,Venepalli, Bhaskar
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p. 127 - 131
(2013/09/07)
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- Mixed Dialkylaluminum Chlorides and Mixed Trimethylorganoaluminates in Chemoselective 1,4 Addition Reactions to Alkylidene Malonic Acid Diethyl Ester
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Mixed alkyl-methyl- and aryl-methylorganoaluminum chlorides 6 were formed by reaction of methylaluminum dichloride with organolithium or Grignard compounds and used for chemoselective 1,4 addition of higher alkyl, aryl, alkenyl and alkinyl groups to alkylidine malonic esters 1 and 2. As an alternative, mixed trimethylorganoaluminates 7 can also be applied for these Michael addition reactions. For conjugate addition of alkenyl groups to alkylidene malonates 1 and 2, alkenyl diisopropylalanes 10 obtained from alkynes and diisopropylaluminum hydride proved the most efficient reagents. Using these novel mixed organoaluminum compounds, β-branched malonic (carboxylic) acid derivatives 3c, 8, 9 and 11 were obtained in good yields. The method offers a general access to β-branched carboxylic derivatives of quite diverse structure not dependent on the commercial availability of the organoluminum chlorides.
- Maas, Steffen,Kunz, Horst
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p. 396 - 403
(2007/10/03)
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- Use of the Nonionic Superbase P(MeNCH2CH2)3N in the Selective Monoalkylation of Active-Methylene Compounds
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The symmetric active-methylene compounds CH2(CO2Et)2 and CH2[C(O)Me]2 are selectively monoalkylated in the presence of 1.1 equiv of a variety of alkyl halides and 1 equiv of the nonionic Superbase P(MeNCH2CH2)2N in 85-98% yields in 30 min at room temperature. The unsymmetrical active-methylene compound EtO2CCH2C(O)Me is selectively monoalkylated under the same conditions, except for the temperature, which is 0 °C, in 59-88% yields. The observation of selective C- rather than O-alkylation is rationalized in terms of the formation of an enolate whose negatively charged oxygen is sterically protected by a nearby HP(MeNCH2CH2)2N+ counterion in a tight ion pair.
- Arumugam, Subramaniam,McLeod, Dale,Verkade, John G.
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p. 3677 - 3679
(2007/10/03)
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- Samarium(II) iodide promoted reductive ring opening reaction of cyclopropane-1,1-dicarboxylic esters. Synthesis of substituted 5-Pentanolides from carbonyl compounds and dimethyl cyclopropane-1,1-dicarboxylate
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Dimethyl cyclopropane-1,1-dicarboxylate is readily subjected to reductive ring opening reaction with samarium(II) iodide in the presence of tris(dibenzoyl-methiodo)iron(III). The generated organosamarium intermediate is trapped by aliphatic ketones to aff
- Imamoto, Tsuneo,Hatajima, Toshihiko,Yoshizawa, Takeshi
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p. 7805 - 7808
(2007/10/02)
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- Synthesis of a new chiral phase-transfer catalyst: Chemical activity in alkylation reactions
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A new chiral phase-transfer catalyst (3S,4S)-1-benzyl-1-methyl-3,4- pyrrolidin-diol-onium iodide (2) synthesized, is found to be more active than the conventional tetraaklylammonium salts in alkylation reactions on active methylene compounds under usual solid-liquid phase-transfer conditions.
- Valli,Sarma,Choudary
-
p. 481 - 482
(2007/10/02)
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- Synthesis and Liquid Crystal Properties of Dimethylene Linked Compounds Incorporating the Cyclobutane or Spiroheptane Rings
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The preparation of sixteen dimethylene linked compounds is described heptane ring>, and a comparison is made between the transition temperatures of these compounds and those of the corresponding esters.This comparison once again highlights the fact that the cyclobutane ring should be regarded, in terms of its ability to promote nematic thermal stability, as a "chain stiffener rather than as a ring system.A comparison is also made of the nematic thermal stabilities of the trans-cyclobutane and the spiroheptane systems and of the trans-cyclohexane and the spiroundecane systems.
- Chan, L. K. M.,Gemmell, P. A.,Gray, G. W.,Lacey, D.,Toyne, K. J.
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p. 229 - 246
(2007/10/02)
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- ORGANOMANGANESE (II) REAGENTS XV. CONJUGATE ADDITION OF ORGANOMANGANESE REAGENTS TO ALKYLIDENEMALONIC ESTERS AND RELATED COMPOUNDS
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Organomanganese reagents react with alkylidenemalonic esters or related compounds to give the conjugate addition products in good yields.Several examples illustrate the scope and the efficiency of this reaction.
- Cahiez, Gerard,Alami, Mouad
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p. 4163 - 4176
(2007/10/02)
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- Synthesis and liquid crystal properties of compounds incorporating cyclobutane, spiroheptane and dispirodecane rings
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A number of esters of structure (I) incorporating the cyclobutane, spiroheptane, or dispirodecane rings has been prepared using a diethyl malonate synthesis.Strict comparison of the liquid crystal behaviour amongst the three classes containing a terminal cyano-substituent was not possible because both the cyclobutanes and dispirodecanes are mixtures of cis- and trans-isomers; the spiroheptanes are racemic systems.Using preparative hplc, it was however possible to isolate the pure cis- and trans-isomers of two of the cyano-substituted cyclobutane esters (I; R = alkyl, -X- = --, Y = CN).From the physical data and the results for the corresponding spiroheptane esters, conclusions regarding the effects of these ring systems on liquid crystal behaviour were obtained.The pure cis- and trans-isomers of the cyclobutane ester (I, R = C3H7, -X- = --, Y = CN) have been assessed for the trends in both order parameter and viscosity with temperature; the results support the idea that idea that the trans-cyclobutane ring adopts a more planar conformation at higher temperatures.Keywords: cyclobutane- and related spiro-systems, cis-/trans-isomerism, order parameter, briefringence, viscosity, structure/property relations.
- Chain, L. K. M.,Gemmel, P. A.,Gray, G. W.,Lacey, D.,Toyne, K. J.
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p. 113 - 140
(2007/10/02)
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- Kinetic and equilibrium studies of the ?-adduct forming reactions of 1,3,5-trinitrobenzene and picryl chloride with some carbon bases
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Reaction of 1,3,5-trinitrobenzene (TNB) with the malononitrile anion in methanol yields a carbon-bonded ?-adduct, (3).Ionisation of the remaining exocyclic hydrogen is favourable and yields the dianinon (4).The initial reaction of 1-chloro-2,4,6-trinitrob
- Crampton, Michael R.,Kee, Terence P.,Wilcock, Jennifer R.
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p. 1714 - 1720
(2007/10/02)
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- ALKYLATION OF MALONIC ESTER AND MONOALKYLMALONIC ESTERS UNDER THE CONDITIONS OF PHASE-TRANSFER CATALYSIS
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Simple procedures were developed for the monoalkylation of malonic ester in the potassium hydroxide-DMFA (DMFA-acetone)-triethylbenzylammonium chloride system and the alkylation of alkylmalonic esters to dialkylmalonic esters in the calcium oxide-DMFA system.
- Sukhanov, N. N.,Trappel', L. N.,Chetverikov, V. P.,Yanovskaya, L. A.
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p. 2288 - 2290
(2007/10/02)
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- LIQUID CRYSTAL MATERIALS WITH SULFUR ATOMS INCORPORATED IN THE PRINCIPAL STRUCTURE: 1. NEW LIQUID CRYSTAL COMPOUNDS WITH 1,3-DITHIANE RING.
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2-(p-Substituted phenyl)-5-alkyl-1,3-dithianes, new liquid crystals, were synthesized by the thioacetalization of the corresponding aldehydes and dithiols. These compounds have characteristic supercooling states, exhibit monotropic liquid crystal phases even in the case of long terminal alkyl substituents. The mesomorphic characteristics of these compounds were different from those of the corresponding 1,3-dioxanes, this must originate in the difference in the molecular width caused by the difference in the atomic volume between sulfur and oxygen.
- Haramoto,Nobe,Kamogawa
-
p. 1966 - 1969
(2007/10/02)
-
- TWO-CARBON MICHAEL ACCEPTORS. ACETYL CATION EQUIVALENTS
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Base-induced Michael condensation of chloromethoxyvinyl phenyl sulfoxides or sulfones with active methylene compounds were examined.The newly introduced functionalized substituents were converted into acetyl group by the subsequent treatment.
- Kinoshita, Hitoshi,Hori, Isaburo,Oishi, Takeshi,Ban, Yoshio
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p. 1517 - 1520
(2007/10/02)
-
- 277. Structure and Chemistry of Malonylmethyl- and Succinyl-Radicals. The Search for Homolytic 1,2-Rearrangements
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Malonylmethyl radical I and its thioester analogue II were generated by standard photolytic and thermolytic methods from perester and bromo precursors.The structures of I and II were examined by ESR spectroscopy and found to exist in preferred conformations.However, no indication for their rearrangement by 1,2-shift of either an ethoxycarboxyl or (ethylthio)carbonyl group to the corresponding succinyl radicals III and IV, respectively, was found at temperatures below -40 deg C.At higher temperatures of up to 140 deg C, the search for malonylmethyl -> succinyl rearrangement was examined by thorough-product analysis of the perester decomposition.There is evidence for the rearrangement of the radical I to III by photolysis and of the radical II to IV by thermolysis at 130 deg C in chlorobenzene to only a small extent.
- Aeberhard, Urs,Keese, Reinhart,Stamm, Erich,Voegeli, Ulrich-Christian,Lau, Willy,Kochi, Jay Kazuo
-
p. 2740 - 2759
(2007/10/02)
-
- Hydrogenolysis of Small Cycloalkanes, VII. Selective Hydrogenation of 1,1-Disubstituted Cyclopropane Derivatives
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On hydrogenation of 1,1-disubstituted cyclopropane derivatives 1 hydrogenolysis of the C-2-C-3 bond to yield 2 is promoted by electron releasing groups (R =alkyl, CH2OH, OR).On the other hand the presence of electron attracting substituents (R = CO2R, COR, CN) causes opening of the C-1-C-2 bond and formation of products 3. 1,1-Bis(trifluoromethyl)cyclopropane could not be hydrogenated.
- Groeger, Claus,Musso, Hans,Rossnagel, Ingrid
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p. 3621 - 3628
(2007/10/02)
-
