- Fe(III)-Catalyzed Aerobic Intramolecular N-N Coupling of Aliphatic Azides with Amines
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An Fe(III)-catalyzed intramolecular N-N coupling of aliphatic azidoamines that forms diverse five- and six-membered semisaturated diazoheterocycles using air as an oxidant is reported, providing an alternative to hydrazine-based methods. Mechanistic studies suggest that a N-radical induced intramolecular homolytic substitution (SH2) is involved in ring closure. The power of this N-N bond-forming method is also demonstrated by using it as the final step in a total synthesis of (-)-newbouldine.
- Zhang, Yue,Duan, Dongyu,Zhong, Ying,Guo, Xin-Ai,Guo, Jiawei,Gou, Jing,Gao, Ziwei,Yu, Binxun
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supporting information
p. 4960 - 4965
(2019/09/03)
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- 1,4-dichlorobutane production technology
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The invention provides a 1,4-dichlorobutane production technology. The technology comprises the following steps: 1, preparing 1,4-butanediol, triphosgene, a catalyst and a reaction kettle with an elevated tank, wherein a molar ratio of the 1,4-butanediol to triphosgene is 1:(0.66-0.70); 2, pumping 60-90% of the 1,4-butanediol weighed in step 1 into the reaction kettle, heating the 1,4-butanediol to 40-70 DEG C, adding the triphosgene, and performing stirring until complete dissolving is achieved; 3, pumping the 1,4-butanediol remained the after step 1 and the catalyst into the elevated tank ofthe reaction kettle, performing dissolving until clarity in the reaction kettle, slowly dropwise adding a solution obtained in the elevated tank into the reaction kettle, and collecting a gas generated by a reaction; and 4, lowering the temperature to 0-30 DEG C after the reaction is finished, standing for layering, and collecting the obtained lower yellowish oily liquid to complete the preparation of 1,4-dichlorobutane. The 1,4-dichlorobutane production technology has the advantages of simplicity in operation, mild reaction conditions, greenness, no pollution, low carbon, environmental protection, and realization of large-scale production.
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Paragraph 0026-0036
(2019/10/23)
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- Ru-Photoredox-Catalyzed Decarboxylative Oxygenation of Aliphatic Carboxylic Acids through N-(acyloxy)phthalimide
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Decarboxylative aminoxylation of aliphatic carboxylic acid derivatives with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) in the presence of ruthenium photoredox catalysis is reported. The key transformation entails a highly efficient photoredox catalytic cycle using Hantzsch ester as a reductant. The ensuing alkoxyamine can be readily converted to the corresponding alcohol in one pot, representing an alternative approach to access aliphatic alcohols under photoredox conditions.
- Zheng, Chao,Wang, Yuting,Xu, Yangrui,Chen, Zhen,Chen, Guangying,Liang, Steven H.
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supporting information
p. 4824 - 4827
(2018/08/24)
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- Oxone: A convenient reagent for the oxidation of acetals
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Symmetrical cyclic and acyclic acetals by oxidation with Oxone gave the corresponding esters in good yield. Treatment of tetrahydropyranyl derivatives of alcohols with the same reagent resulted in oxidative regeneration of the alcohols.
- Curini, Massimo,Epifano, Francesco,Marcotullio, Maria Carla,Rosati, Ornelio
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p. 777 - 779
(2007/10/03)
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- Remarkable deprotection of THP and THF ethers catalysed by cerium ammonium nitrate (CAN) under neutral conditions
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The catalytic deprotection of a range of functionalised THP and THF ethers can be efficiently performed, under neutral conditions, using as little as 3 mol% CAN in MeCN/borate buffer (pH = 8).
- Marko, Istvan E.,Ates, Ali,Augustyns, Benoit,Gautier, Arnaud,Quesnel, Yannick,Turet, Laurent,Wiaux, Marianne
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p. 5613 - 5616
(2007/10/03)
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- Transformation of OH-adduct of 1-chloro-4-iodobutane into intra-molecular radical cation in neutral aqueous solution
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The iodine centered OH-adduct formed on reaction of OH radicals with 1-chloro-4-iodobutane in neutral aqueous solution transforms (k=5.4×105 s-1) to an intra-molecular radical cation (). The unfavorable structural conformation of solute radical cation generated on reaction of OH radicals with 1-chloro-5-iodopentane does not allow the transformation of OH-adduct into an intra-molecular radical and instead a dimer radical cation () is formed.
- Mohan, Hari,Maity,Chattopadhyay,Mittal
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p. 493 - 498
(2007/10/03)
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- Substituted diether diols by ring-opening of carbocyclic and stannylene acetals
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Reduction of malonaldehyde bis(ethylene and propylene acetals) with borane or monochloroborane produces diether diols 1 and 2 in high yield. Similar reduction of glyoxal his(ethylene acetals) has only limited utility for the preparation of tetrasubstituted triethylene glycols 3. Organotin chemistry is complementary: stannylene acetals prepared from disubstituted vicinal diols can be alkylated with half an equivalent of 1,2-dibromoethane to produce tetrasubstituted triethylene glycols 3, or with two equivalents of 2-chloroethanol to produce disubstituted triethylene glycols 4.
- Martinez-Bernhardt, Rolando,Castro, Peter P.,Godjoian, Gayane,Gutierrez, Carlos G.
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p. 8919 - 8932
(2007/10/03)
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- Asymmetric Conversion of Arenechromium Complexes to Functionalized Cyclohexenones: Progress toward Defining an Optimum Chiral Auxiliary
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An investigation into the asymmetric synthesis of 5-substituted cyclohexenones via nucleophile addition to (alkoxyarene)chromium tricarbonyl complexes is described. Diastereoselectivity during the nucleophile addition step was achieved using alkoxy substituents derived from terpenoid substrates as chiral auxiliaries. Selectivities as high as 24:1 were obtained when 2-phenylisoborneol was used as the chiral auxiliary and as high as 17:1 using 3,3-(ethylenedioxy)isoborneol. The absolute stereochemistry of the major products was assigned by Mosher's method, after their conversion to the corresponding cyclohexenol. A study of the temperature dependence of the nucleophile addition to alkoxytoluene complexes revealed a thermodynamic preference for addition ortho to the ether substituent.
- Pearson, Anthony J.,Gontcharov, Alexander V.
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p. 152 - 162
(2007/10/03)
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- Formation, Stability, and Reactivity of Radical Cations of 1-Bromo-n-chloroalkanes in Aqueous Solution: A Pulse Radiolysis Study
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Hydroxyl radicals are able to form solute radical cations in acidic aqueous solutions of 1-bromo-n-chloroalkanes (n=1-6).Depending on the value of n, the bromine centered radical cation stabilizes on coordination with an unoxidized bromine atom from another molecule (intermolecular) or with an unoxidized chlorine atom of the same molecule (intramolecular).With n=2, 5, and 6, only dimer radical cations (λmax=430-450 nm) are formed through intermolecular coordination whereas, with n=1, 3, and 4, radical cations are stabilized both by intra- and intermolecular coordination, forming intramolecular radical cations (λmax=380 nm) or dimer radical cations (λmax=425-440 nm) at low and high solute concentrations, respectively.Cl2.- is unable to undergo an electron transfer reaction with 1-bromo-2-chloroethane whereas SO4.- is able to react with 1-bromo-2-chloroethane with a bimolecular rate constant of 8.3 * 106 dm3 mol-1 s-1.The dimer radical cation of 1-bromo-2-chloroethane is a strong one-electron oxidant and is able to undergo electron transfer reaction with a number of molecules with high rate constant values (109 dm3 mol-1 s-1).The dimer radical cation decays by a deprotonation mechanism, and the stability constant is determined to be 147 dm3 mol-1 at 25 deg C.Quantum chemical calculations of the strength of the three-electron bond between two heteroatoms at a semiempirical level with AMI parametrization show good correlation with experimental results.Good correlation, between experimantal results and theoretical calculations, is also observed for variation of the net atomic charge over bromine, the ionization potential (IP) of the molecule, and the difficulty of oxidation of various alkyl halides.
- Maity, D. K.,Mohan, H.,Chattopadhyay, S.,Mittal, J. P.
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p. 12195 - 12203
(2007/10/02)
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- Process for preparing fibrinogen receptor antagonists
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The invention is a highly efficient synthesis for making compounds of the formula: STR1 wherein: R1 is a six member saturated or unsaturated heterocyclic ring containing one or two heterocyclic atoms wherein the heteroatoms are N; or NR6, wherein R6 is H or C1-10 alkyl; m is an integer from two to six; and R4 is aryl, C1-10 alkyl, or C4-10 aralkyl.
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- Synthesis of the Alkaloid Homaline in (+/-) and Natural (S,S)-(-) Forms, using Amination and Transamidative Ring Expansion in Liquid Ammonia
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Synthesis of the alkaloid homaline in (+/-) and natural (S,S)-(-) forms is reported.Linking of 2-azacyclooctanone units either directly or successively using 1,4-dihalogenobutanes or 1,4-dihalogenobut-2-ynes is examined. (+/-)-5-Methyl-4-phenyl-1,5-diazacyclooctan-2-one is first made by a 2,2'-dithiodipyridine/triphenylphosphine-mediated cyclisation, and then by amination and transamidative ring expansion from N-(3-chloropropyl)-4-phenylazetidin-2-one in liquid ammonia, followed by N-methylation.Coupling through a 1,4-dihalogenobutane of either the N-methylated azalactam, or the unmethylated azalactam followed by methylation, gave homaline in (+/-) and meso forms. (R)-(-)-Phenylglycine was converted via (S)-β-phenyl-β-alanine into an (S)-β-lactam which was then alkylated with 1-bromo-3-chloropropane, and aminated and ring expanded in liquid ammonia.Coupling of the homochiral azalactam (2 mol) so formed with 1,4-dibromobutane, followed by N-methylation, gave (S,S)-(-)-homaline identical with the natural material.
- Crombie, Leslie,Haigh, David,Jones, Raymond C. F.,Mat-Zin, Ab. Rasid
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p. 2047 - 2054
(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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- Pheromone Synthesis, CXXXI Synthesis of the Four Stereoisomers of 6,10,13-Trimethyl-1-tetradecanol, Aggregation Pheromone of Predatory Stink Bug, Stiretrus anchorago
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The synthesis of the four stereoisomers of 6,10,13-trimethyl-1-tetradecanol (1a), the male-produced aggregation pheromone of the predatory stink bug Stiretrus anchorago, was achieved by starting from (R)-citronellol (2a), methyl (R)- or (S)-3-hydroxy-2-methylpropanoate (10) and 4-chloro-1-butanol (12a). - Key Words: Grignard coupling / Phenyl sulfone, alkylation of / Pheromone, enantiomerically pure / Stiretrus anchorago / 1-Tetradecanol, 6,10,13-trimethyl- / Sulfones
- Mori, Kenji,Wu, Jiang
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p. 783 - 788
(2007/10/02)
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- Towards the total synthesis of clerodin. Part I
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A highly stereo- and enantioselective approach to clerodin 1, an insect antifeedant, is described. The key step involved the stereospecific formation of the C9-C11 bond, at an early stage of the synthesis, using a Claisen rearrangement.
- Bouchard,Renard,Lallemand
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p. 5953 - 5956
(2007/10/02)
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- SYNTHESIS OR FORMYLCYCLOPROPANE, ALKYL CYCLOPROPYL KETONES, AND CYCLOPROPYLCARBINOLS ON THE BASIS OF γ-ELIMINATION UNDER THE CONDITIONS OF PHASE-TRANSFER CATALYSIS
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A preparative method was developed for the synthesis of formylcyclopropane and alkyl cyclopropyl ketones on the basis of the method proposed for the production of 4-chlorobutanal and alkyl 3-chloropropyl ketones.With ethylmagnesium bromide formylcyclopropane gives a high yield of 1-cyclopropyl-1-propanol.
- Khusid, A. Kh.
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p. 112 - 115
(2007/10/02)
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- Synthesis of 4-haloalkyl alcohols
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Disclosed is a process for preparing 4-haloalkyl alcohols by reacting tetrahydrofuran derivatives and hydrogen halides in the presence of a resinous quaternary ammonium halide catalyst, preferably styrene-divinyl benzene copolymer resins having pendant N(R)3 X, where X is halogen, or N(R)2 groups of tetrahydrofuran. The haloalcohols are useful intermediates for the preparation of dyes, halogenated polymers, pharmaceuticals, polymerization catalysts and plasticizers.
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- SYNTHESIS OF HIGHER ACETYLENIC ALCOHOLS
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The alkylation of 1-alkynes in various solvents was investigated, and the optimum conditions for the production of acetylenic alcohols were obtained.
- Kovalev, B. G.,Matveeva, E. D.,Stan, V. V.,Vovk, G. A.,Yudin, L. G.,Kost, A. N.
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p. 1728 - 1733
(2007/10/02)
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