- In-situ-generation of alkylsilyl peroxides from alkyl hydroperoxides and their subsequent copper-catalyzed functionalization with organosilicon compounds
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Alkylsilyl peroxides were generated in situ from the corresponding alkyl hydroperoxides using organosilicon compounds of the type Me3SiX (X = CN, N3, and halogens) and an amine base. Subsequent in situ copper-catalyzed homolytic cleavage of the alkylsilyl peroxides afforded alkyl radicals, which were then trapped with X (X = CN, N3, and halogens) to furnish products with new carbon-carbon, carbon-nitrogen, or carbon-halogen bonds in good to high yields.
- Xu, Weiping,Zhong, Wenfeng,Yang, Qin,Kato, Terumasa,Liu, Yan,Maruoka, Keiji
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- Controlling Selectivity by Controlling Energy Partitioning in a Thermal Reaction in Solution
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The comparison of experimental and predicted kinetic isotope effects in the α-cleavage of alkoxy radicals is used here to judge the applicability of statistical rate theories. It is found that the governing rate theory and the statistical versus nonstatistical nature of the cleavage depend on the cleavage barrier and how much energy is imparted to the radical. The latter can then be controlled by changing the size of substituents in the system. With a large alkyl group substituent, the vibrational energy of the alkoxy radical is increased, but this energy is not statistically distributed, leading to a lower isotope effect than predicted by statistical theories. The observed isotope effect can be approximately rationalized using a semistatistical localized RRKM model.
- Kurouchi, Hiroaki,Andujar-De Sanctis, Ivonne L.,Singleton, Daniel A.
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- Palladium-Catalyzed Aerobic Anti-Markovnikov Oxidation of Aliphatic Alkenes to Terminal Acetals
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Terminal acetals were selectively synthesized from various unbiased aliphatic terminal alkenes and 1,2-, 1,3-, or 1,4-diols using a PdCl2(MeCN)2/CuCl catalyst system in the presence of p-toluquinone under 1 atm of O2 and mild reaction conditions. The slow addition of terminal alkenes suppressed the isomerization to internal alkenes successfully. Electron-deficient cyclic alkenes, such as p-toluquinone, were key additives to enhance the catalytic activity and the anti-Markovnikov selectivity. The halogen groups in the alkenes were found to operate as directing groups, suppressing isomerization and increasing the selectivity efficiently.
- Komori, Saki,Yamaguchi, Yoshiko,Kataoka, Yasutaka,Ura, Yasuyuki
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p. 3093 - 3099
(2019/03/29)
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- Cobaloxime-catalyzed hydration of terminal alkynes without acidic promoters
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Cobaloxime (Co(dmgBF2)2·2H2O), an inexpensive first-row transition-metal complex, catalyzed hydration of terminal alkynes gave the corresponding methyl ketones in good to excellent yields under neutral conditions (additional protic acids and silver salts are not required). A wide range of functional groups, such as allyl ether, benzyl ethers, carboxylic esters, imides, amides, nitro, and halogens, were tolerated. The mild reaction conditions together with the inexpensive feature and easy availability of the catalyst well address the current challenges in the field of alkyne hydration.
- Hou, Shengtai,Yang, Hongjian,Cheng, Bin,Zhai, Hongbin,Li, Yun
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supporting information
p. 6926 - 6929
(2017/07/10)
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- Micellar catalysis-enabled sustainable ppm Au-catalyzed reactions in water at room temperature
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Several ppm level gold-catalyzed reactions enabled by the ligand HandaPhos can be performed at room temperature in aqueous nanoreactors composed of the surfactant Nok. Variously substituted allenes undergo cycloisomerization leading to heterocyclic products in good yields. Likewise, cyclodehydration is also illustrated under similar conditions, as is an intermolecular variant, hydration of terminal alkynes. Recycling of the catalyst and reaction medium is also illustrated. A low E factor associated with limited solvent use and therefore, waste generation, documents the greenness of this process.
- Klumphu, Piyatida,Desfeux, Camille,Zhang, Yitao,Handa, Sachin,Gallou, Fabrice,Lipshutz, Bruce H.
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p. 6354 - 6358
(2017/08/29)
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- Secondary Phosphine Oxides as Multitalented Preligands En Route to the Chemoselective Palladium-Catalyzed Oxidation of Alcohols
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Secondary phosphine oxides O=PHR2 (SPOs) were identified as multitalented preligands for the chemoselective Pd-catalyzed oxidation of alcohols by a hydrogen-abstracting methodology. SPOs were found to promote the hydrogen-abstraction step as well as hydrogen transfer to a Michael acceptor by generating a putative active H?Pd species. The catalytic system operates under neutral conditions and was proven to be compatible with various electrophilic and nucleophilic functionalities within the substrates as well as water- and air-sensitive functional groups.
- Vasseur, Alexandre,Membrat, Romain,Gatineau, David,Tenaglia, Alphonse,Nuel, Didier,Giordano, Laurent
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p. 728 - 732
(2017/03/13)
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- Hydration of alkynes at room temperature catalyzed by gold(I) isocyanide compounds
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An effective method using gold(I) isocyanide complexes as catalysts for the transformation of various alkynes to the corresponding ketones is successfully developed. The hydration process proceeds smoothly at room temperature with quite high yield (up to 99%). The catalytic center is the isocyanide-Au(I)+ cation. Further theoretical research reveals a direct hydration mechanism by H2O, and the rate-determining step has an energy barrier of 23.7 kcal mol?1. These results show a good example to reduce unnecessary steps and achieve milder reaction conditions at the same time for the hydration of alkynes.
- Xu, Yun,Hu, Xingbang,Shao, Jing,Yang, Guoqiang,Wu, Youting,Zhang, Zhibing
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supporting information
p. 532 - 537
(2018/04/16)
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- Formal hydration of non-activated terminal olefins using tandem catalysts
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The hydration of terminal olefins to secondary alcohols has been achieved using a Pd(ii)/Ru(ii) catalyst combination with high regioselectivity and yields. Both vinyl arenes and aliphatic olefins can be hydrated easily with the tandem catalyst system using a low catalyst loading of 1 mol%. The Royal Society of Chemistry 2014.
- Yang, Yongsheng,Guo, Jiayi,Ng, Huimin,Chen, Zhiyong,Teo, Peili
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supporting information
p. 2608 - 2611
(2014/03/21)
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- Direct conversion of N-methoxy-N-methylamides (Weinreb amides) to ketones via a nonclassical Wittig reaction
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(Chemical Equation Presented) N-Methoxy-N-methylamides (Weinreb amides) are converted efficiently into ketones by reaction with alkylidenetriphenylphosphoranes and in situ hydrolysis of the product.
- Murphy, John A.,Commeureuc, Aurelien G. J.,Snaddon, Thomas N.,McGuire, Thomas M.,Khan, Tanweer A.,Hisler, Kevin,Dewis, Mark L.,Carling, Robert
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p. 1427 - 1429
(2007/10/03)
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- Synthesis of 1-(n-hexyl-5-one)-2-chlorobenzimidazole
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o-Phenylenediamine on condensation with urea gives the known benzimidazolin-2-one, which on reaction with phosphoryl chloride in the presence of catalytic amount of phenol yields the already reported 2- chlorobenzimidazole. The latter on alkylation with 6-chloro-2-hexanone in the presence of K2CO3 in DMF medium, gives the title compound.
- Dubey,Naidu,Anandam,Hemasunder
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p. 1239 - 1242
(2007/10/03)
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- Oxidation of 1-alkylcycloalkanols with PbIV and MnIII compounds under mechanical activation
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A mechanoactivated solid-state oxidative decyclization of 1-alkylcycloalkanols under the action of the Pb(OAc)4-MX or Mn(OAc)3-MX systems (MX is a metal halide) was carried out for the first time. The reaction affords exclusively ω-haloalkanones.
- Kapustina,Sokova,Makhaev,Petrova,Nikishin
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p. 2080 - 2082
(2007/10/03)
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- Generation and synthetic application of metallated methyl isopropenyl ether, a substitute for acetone enolate
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Methyl isopropenyl ether (1) has been metallated at low temperature with a 1:1 molar mixture of n-BuLi/t-BuOK in THFhexane, and subsequently functionalized with a variety of electrophilic reagents. At temperatures higher than -30°C, the metallated methyl isopropenyl ether (2) decomposes with formation of allene. When the suspension of 2 is allowed to warm up to room temperature in the presence of an additional equivalent of n-BuLi, the intermediary aliene is converted into 1-propynyllithium (2c), which reacts with propyl thiocyanate to give 1-propylthio-1-propyne (4). Some of the functionalization products were subjected to acidic hydrolysis affording the expected methyl ketones. VCH Vcrlagsgescllschaft mbH.
- Taherirastgar, Foroogh,Brandsma, Lambert
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- Dienediolates of unsaturated carboxylic acids in synthesis. Aldehydes and ketones from alkyl halides, by ozonolysis of β,γ-unsaturated α-alkyl carboxylic acids. The role of a tertiary amine in the cleavage of ozonides
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A convenient two-step procedure for a two carbon homologative conversion of alkyl halides into aldehydes and methyl ketones by α-alkylation of unsaturated carboxylic acids, followed by ozonolysis is developed and applied to the synthesis of ω-chloro aldehydes. Triethylamine is superior to dimethyl sulfide or triphenylphosphine for cleavage of the ozonides, except when aldol condensation side reactions require use of protic solvents and iodide salts. Cleavage of the ozonides by triethylamine is shown to occur mainly through a reductive process.
- Aurell, Maria Jose,Ceita, Luisa,Mestres, Ramon,Tortajada, Amparo
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p. 10883 - 10898
(2007/10/03)
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- Process for preparing 6-chloro-2-hexanone from 1-methylcyclopentane
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A process for preparing 6-chloro-2-hexanone which comprises the steps of (a) oxidizing methylcyclopentane with ozone in the presence of a carboxylic acid and for a sufficient period of time to form 1-methylcyclopentanol; (b) reacting said 1-methylcyclopentanol with a suitable amount of an alkali metal hypochlorite in the presence of a carboxylic acid to form 1-methylcyclopentyl hypochlorite; and (c) heating said 1-methylcyclopentyl hypochlorite for a sufficient period of time to form 6-chloro-2-hexanone.
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- Process for preparing omega-halo-ketones
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A process for preparing 6-chloro-2-hexanone which comprises the steps of (a) dehydrating cyclohexanol in the presence of a suitable catalyst and at a suitable temperature and for a sufficient period of time to form cyclohexene; (b) rearranging said cyclohexene at a higher temperature than in step (a) in the presence of a suitable catalyst and for a sufficient period of time to form 1-methylcyclopentene; (c) hydrating said 1-methylcyclopentene at a temperature lower than step (b) and in the presence of a resin catalyst for a sufficient period of time to form 1-methylcyclopentanol; (d) reacting said 1-methylcylcopentanol with a suitable amount of an alkali metal hypochlorite in the presence of a carboxylic acid to form 1-methylcyclopentyl hypochlorite; and (e) heating said 1-methylcyclopentyl hypochlorite for a sufficient period of time to form 6-chloro-2-hexanone.
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- INSECT PHEROMONES AND THEIR ANALOGUES. XXXV. SYNTHESIS OF (R)-(-)-10-METHYLTRIDECAN-2-ONE - THE PHEROMONE OF Diabrotica undecimpunctata
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A scheme has been developed for the synthesis of (R)-(-)-10-methyltridecan-2-one, the sex pheromone of the southern corn rootworm (Diabrotica undecimpunctata) using as the chiral synthon (R)-(+)-methylheptenal obtained by the hydroperoxide oxidation of the readily available (S)-(+)-dihydromyrcene.
- Odinokov, V. N.,Kukovinets, O. S.,Kasradze, V. G.,Tsyglintseva, E. Yu.,Serebryakov, E. P.,Tolstikov, G. A.
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p. 106 - 109
(2007/10/02)
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- The synthesis of β-keto lactones via cyclization of β-keto ester dianions or the cyclization of Meldrum's acid derivatives
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Two new methods to synthesize macrocyclic β-keto lactones have been developed.The first involves the synthesis of ω-halo-β-keto esters and an intramolecular alkylation of the dianions to these compounds.The reaction is complicated by elimination in the small and medium ring systems and by difficulties in purifying the final products.However, it is possible to obtain modest yields of the desired β-keto lactones.This procedure was used to synthesize the 25- and 27-membered ring β-hydroxy lactones that are the constituents of termite defense compounds.The second method involves the thermolysis of acylated Meldrum's acid derivatives, which leads directly to β-keto lactones.This process gives modest yields of macrocyclic systems and good yield of the unsubstituted 3-oxopentan-5-olide (25) .The 14-membered macrocyclic β-keto lactone 9j has a complex 1H NMR spectrum, which has been interpreted in terms of multiple conformations.The temperature dependence of the NMR spectrum of 9j is consistent with entropic, rather than enthalpic, control of the equilibrium.Quasiharmonic entropy calculations are consistent with this model.
- Lermer, Leonard,Neeland, Edward G.,Ounsworth, James P.,Sims, Russell J.,Tischler, Samuel A.,Weiler, Larry
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p. 1427 - 1445
(2007/10/02)
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- La reaction d'ω-azidocetones avec la triphenylphosphine: une voie d'acces generale aux imines cycliques
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The ω-azidoketones RC(=O)-CH(R')-(CH2)n-CH(R'')-N3 react with triphenylphosphine in anhydrous media to give 5, 6 and 7 membered cyclic imines via an intramolecular aza-Wittig reaction with good yields.A general synthesis of ω-haloketones which are the precursors of the azidoketones was also devised.
- Vaultier, M.,Lambert, P. H.,Carrie, R.
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- METAL-HALOGEN EXCHANGE-INITIATED CYCLIZATION OF IODO CARBONYL COMPOUNDS
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The feasability of constructing carbocycles through the metal-halogen exchange-initiated cyclization reactions of iodoketones and other carboxyl derivatives has been studied.With saturated primary iodides, cyclization predominates when deactivated ketones are employed.
- Cooke, Manning P.,Houpis, Ioannis N.
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p. 4987 - 4990
(2007/10/02)
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- CHIMIE ORGANOMETALLIQUE SOUS HAUTE PRESSION: REACTION DES CHLOROCETONES AVEC L'HYDRURE DE TRIBUTYLETAIN
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High-pressure reaction of tributyltin hydride with several chloroketones (3-chloro-2-butanone, 4-chloro-2-butanone, 5-chloro-2-pentanone, 6-chloro-2-hexanone and 7-chloro-2-heptanone) led to the formation of chloroalkoxytins or cyclic ethers.An ionic mechanism, starting with nucleophilic attack at the carbonyl group, is proposed to explain the formation of the reaction products.
- Degueil-Castaing, M.,Maillard, B.,Rahm, A.
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- Synthesis and Thermolysis of O-Alkyl-N-vinylhydroxylamine Derivatives
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Oxoiminium salts 11 a-e and 13 a-e have been prepared from the ο-chloroketones 9 a-e by oximation via the cyclic oxime ethers 10 a-e and the cyclic imine oxides 12 a-e, followed by alkylation with "Meerwein salt".The deprotonation reaction of 11 a-e and 13 a-e yields, via the regioselectively prepared intermediates 14 a-e and 17 a-e, the α, β-unsaturated imines 15 a-e and the cyclic imines 18 a-e, respectively.
- Shatzmiller, Shimon,Shalom, Eytan
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p. 897 - 905
(2007/10/02)
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- rac-(E)-10-HYDROXY-4,10-DIMETHYLDODECA-4,11-DIEN-2-ONE. A NEW STEREOSELECTIVE SYNTHESIS AND BIOLOGICAL PROPERTIES
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The rac-(E)-10-hydroxy-4,10-dimethyldodeca-4,11-dien-2-one (1) has been submitted to biological tests on the pupae of Tenebrio molitor, its juvenilizing effects cannot compare with those reported by Jacobson for the echinolone, the active principle of Echinacea angustifolia described as the (+) enantiomer of 1.A new stereoselective synthesis of 1 is also reported.
- Orsini, Fulvia,Pelizzoni, Francesca,Sello, Guido,Serini, Graziella Bolchi
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p. 277 - 280
(2007/10/02)
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- FERROUS ION INDUCED DECOMPOSITION OF ALKYL HYPOCHLORITES
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The decomposition of primary, secondary and tertiary alkyl hypochlorites induced by ferrous and other one-electron oxidizable metal ions leads to δ-chloro alcohols in yields of 34-76percent.In decomposition of tertiary alkyl hypochlorites, β-fragmentation competes with intramolecular δ-chlorination.Tertiary cycloalkyl hypochlorites containing five- or six-membered rings undergo β-cleavage giving the corresponding ο-chloro ketones, while 1-methylcycloheptyl and 1-methylcyclooctyl hypochlorites by decomposition with ferrous ion proceed by transannular functionalization of δ-carbon atom and β-cleavage as a competing reaction.
- Cekovic, Zivorad,Djokic, Gordana
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p. 4263 - 4268
(2007/10/02)
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