- Pd-Catalyzed intermolecular C-H bond arylation reactions: Effect of bulkiness of carboxylate ligands
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A bulky carboxylic acid bearing one 1-adamantylmethyl and two methyl substituents at the α-position is demonstrated to work as an efficient carboxylate ligand source in Pd-catalyzed intermolecular C(sp2)-H bond arylation reactions. The reactions proceeded smoothly under mild conditions, taking advantage of the steric bulk of the carboxylate ligands.
- Tanji, Yutaka,Hamaguchi, Ryo,Tsuji, Yasushi,Fujihara, Tetsuaki
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supporting information
p. 3843 - 3846
(2020/04/15)
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- Production process 3 and 3 - dimethyl butyraldehyde
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The invention belongs to the technical field of chemical synthesis and particularly relates to a production technology of 3,3-dimethylbutyraldehyde. The production technology sequentially comprises the following steps: S1, taking tert-butyl alcohol and ethylene as raw materials, taking n-hexane as a reaction solvent, and catalyzing by using sulfuric acid to synthesize 3,3-dimethyl butyl sulfate; S2, under the action of the catalyst, controlling the temperature to be 30 to 50 DEG C and hydrolyzing to obtain 3,3-dimethylbutanol; S3, performing catalyzed oxidation on the 3,3-dimethylbutanol by using an inhibitor 701 and dimethylethyl nitrite to obtain the 3,3-dimethylbutyraldehyde. The production technology has the advantages of safety, reliability, low cost, good reproducibility and high purity of a final product.
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Paragraph 0031; 0034; 0036; 0038; 0040; 0042
(2020/11/13)
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- Reactions of carbene-stabilized borenium cations
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In this paper we probe the reactivity of the borenium cations [C3H2(NCH2C6H4)(NCH2Ph)BH][B(C6F5)4] 2 and [C3H2(NCH2C6H4)2B][B(C6F5)4] 3. The reactions of 2 with cyclohexene or 3,3-dimethyl-1-butene gave the alkyl-aryl borenium salts [PhCH2(CHN)2CCH2C6H4BR][B(C6F5)4] (R = Cy 4, CH2CH2tBu 5) while the corresponding reactions with diphenylacetylene, 1-hexyne and 1-phenyl-1-propyne gave the aryl-alkenyl borenium cation salts [PhCH2(CHN)2CCH2C6H4BC(R1)C(H)R2][B(C6F5)4] (R1 = R2 = Ph 6, R1 = H, R2 = C4H97, R1 = Me, R2 = Ph 8a, R1 = Ph, R2 = Me 8b). In contrast, the reaction of 2 with ethynyldiphenylphosphane or 2-vinylpyridine lead to the formation of the adducts, [PhCH2(CHN)2CCH2C6H4B(H)P(Ph2)CCH][B(C6F5)4] 9, [PhCH2(CHN)2CCH2C6H4B(H)NC5H4C(H)CH2][B(C6F5)4] 10, respectively, while the more bulky donor H2CC(Ph)PMes2 gave 1,2-hydroboration of the phosphinoalkene affording [PhCH2(CHN)2CCH2C6H4BCH2CH(Ph)PMes2][B(C6F5)4] 11. In another vein of reactivity, one or two equivalents of the FLP, PtBu3/B(C6F5)3 is shown to react with 3 to give the zwitterionic borenium-borate species [C2H2(NCH(BC(CHNCH2C6H4)2)C6H4)(NCH(B(C6F5)3)C6H4)CB] 12 and the anionic bis-borate species[tBu3PH][C2H2(NCH(B(C6F5)3)2C6H4)2CB] 13. The implications of these findings are discussed.
- Cao, Levy L.,Farrell, Jeffrey M.,Lam, Jolie,Stephan, Douglas. W.
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p. 1839 - 1846
(2020/02/20)
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- Failure and Redemption of Statistical and Nonstatistical Rate Theories in the Hydroboration of Alkenes
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Our previous work found that canonical forms of transition state theory incorrectly predict the regioselectivity of the hydroboration of propene with BH3 in solution. In response, it has been suggested that alternative statistical and nonstatistical rate theories can adequately account for the selectivity. This paper uses a combination of experimental and theoretical studies to critically evaluate the ability of these rate theories, as well as dynamic trajectories and newly developed localized statistical models, to predict quantitative selectivities and qualitative trends in hydroborations on a broader scale. The hydroboration of a series of terminally substituted alkenes with BH3 was examined experimentally, and a classically unexpected trend is that the selectivity increases as the alkyl chain is lengthened far from the reactive centers. Conventional and variational transition state theories can predict neither the selectivities nor the trends. The canonical competitive nonstatistical model makes somewhat better predictions for some alkenes but fails to predict trends, and it performs poorly with an alkene chosen to test a specific prediction of the model. Added nonstatistical corrections to this model make the predictions worse. Parametrized Rice-Ramsperger-Kassel-Marcus (RRKM)-master equation calculations correctly predict the direction of the trend in selectivity versus alkene size but overpredict its magnitude, and the selectivity with large alkenes remains unpredictable with any parametrization. Trajectory studies in explicit solvent can predict selectivities without parametrization but are impractical for predicting small changes in selectivity. From a lifetime and energy analysis of the trajectories, "localized RRKM-ME" and "competitive localized noncanonical" rate models are suggested as steps toward a general model. These provide the best predictions of the experimental observations and insight into the selectivities.
- Bailey, Johnathan O.,Singleton, Daniel A.
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supporting information
p. 15710 - 15723
(2017/11/14)
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- Chemoselective continuous-flow hydrogenation of aldehydes catalyzed by platinum nanoparticles dispersed in an amphiphilic resin
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A chemoselective continuous-flow hydrogenation of aldehydes catalyzed by a dispersion of platinum nanoparticles in an amphiphilic polymer (ARP-Pt) has been developed. Aromatic and aliphatic aldehydes bearing various reducible functional groups, such as keto, ester, or amide groups, readily underwent flow hydrogenation in aqueous solutions within 22 s in a continuous-flow system containing ARP-Pt to give the corresponding primary benzylic or aliphatic alcohols in ≤99% yield with excellent chemoselectivity. Moreover, the long-term continuous-flow hydrogenation of benzaldehyde for 8 days was realized, and the total turnover number of the catalyst reached 997. The flow hydrogenation system provides an efficient and practical method for the chemoselective hydrogenation of aldehydes bearing reducible functional groups.
- Osako, Takao,Torii, Kaoru,Hirata, Shuichi,Uozumi, Yasuhiro
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p. 7371 - 7377
(2017/11/09)
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- A 3, 3 - dimethyl butyl preparation method (by machine translation)
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The invention discloses a 3, 3 - dimethyl butyl preparation of the preparation method, characterized in that in the ethanol, 3, 3 - dimethyl butyric acid under the acid catalysis ester, then under the action of the borohydride one pot method to obtain the final product 3, 3 - dimethyl-butanol. This invention abolishes the existing literature reports of flammable and explosive reagent (such as lithium aluminum hydride) and a solvent (such as ethyl ether) reaction conditions; in addition, the invention uses the one pot method to obtain the final product, high yield, purity is good, the price of raw materials used low, source is wide, the final product cost, applied to industrial production. (by machine translation)
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Paragraph 0015-0026
(2018/01/13)
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- Vanadium-Catalyzed Oxidative Debenzylation of O-Benzyl Ethers at ppm Level
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An advantageous methodology for the oxidative debenzylation of ethers has been developed. Very low amounts of a catalyst system based on vanadyl acetylacetonate and a triazole type pincer ligand allow the selective oxidative cleavage of a number of O-benzyl ethers in the presence of oxygen as the sole oxidant. The methodology tolerates a number of functional groups such as halo-, alkoxy-, or trifluoromethylarenes, alkyne, alkene, ether, and acetal units. Large-scale deprotections can be also carried out by the optimized procedure, which is amenable to enantioenriched reactants as well. (Figure presented.).
- Urgoitia, Garazi,SanMartin, Raul,Herrero, María Teresa,Domínguez, Esther
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p. 3307 - 3312
(2016/10/21)
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- Organoborane-Catalyzed Hydrogenation of Unactivated Aldehydes with a Hantzsch Ester as a Synthetic NAD(P)H Analogue
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We have developed a method for the hydrogenation of unactivated aldehydes, using a Hantzsch ester as a NAD(P)H analogue in the presence of an electron-deficient triarylborane as a Lewis acid catalyst. Thus, tris[3,5-bis(trifluoromethyl)phenyl]borane efficiently catalyzes the hydrogenation of aliphatic aldehydes with a Hantzsch ester in 1,4-dioxane at 100 °C to give the corresponding aliphatic primary alcohols in up to 97% yield. Aromatic aldehydes also undergo the hydrogenation, even at 25 °C, to furnish the corresponding aromatic primary alcohols in up to 100% yield.
- Hamasaka, Go,Tsuji, Hiroaki,Uozumi, Yasuhiro
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supporting information
p. 2037 - 2041
(2015/09/01)
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- Development of a ruthenium/Phosphite catalyst system for domino hydroformylation-reduction of olefins with carbon dioxide
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An efficient domino ruthenium-catalyzed reverse water-gas-shift (RWGS)-hydroformylation-reduction reaction of olefins to alcohols is reported. Key to success is the use of specific bulky phosphite ligands and triruthenium dodecacarbonyl as the catalyst. Compared to the known ruthenium/chloride system, the new catalyst allows for a more efficient hydrohydroxymethylation of terminal and internal olefins with carbon dioxide at lower temperature. Unwanted hydrogenation of the substrate is prevented. Preliminary mechanism investigations uncovered the homogeneous nature of the active catalyst and the influence of the ligand and additive in individual steps of the reaction sequence.
- Liu, Qiang,Wu, Lipeng,Fleischer, Ivana,Selent, Detlef,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 6888 - 6894
(2014/06/09)
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- The active role of NHC ligands in platinum-mediated tandem hydroboration-cross coupling reactions
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Stable N-heterocyclic platinum-carbene complexes are the first example of platinum-mediated regioselective H-B addition to vinylarenes and alkynes, allowing consecutive cross coupling reactions with the same catalytic system. The Royal Society of Chemistry.
- Lillo, Vanesa,Mata, Jose A.,Segarra, Anna M.,Peris, Eduardo,Fernandez, Elena
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p. 2184 - 2186
(2008/02/08)
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- Process for the preparation of 3,3-dimethylbutanal
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3,3-Dimethylbutanal is prepared from 3,3-dimethylbutanol. Intermediate 3,3-dimethylbutanol is obtained by reacting ethylene, isopropylene and sulfuric acid to produce a 3,3-dimethylbutyl ester which is hydrolyzed to the alcohol. The hvdrolysis step is effectively carried out by reactive distillation. Alternatively, 3,3-dimethylbutanal is prepared from 3,3-dimethylbutanol obtained by reduction of the corresponding carboxylic acid or 1,2-epoxy-3,3-dimethylbutane, or by hydrolysis of 1-halo-3,3-dimethylbutane. Fixed bed gas phase and stirred tank liquid phase processes are provided for converting 3,3-dimethylbutanol to 3,3-dimethylbutanal by catalytic dehydrogenation.
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- Transition-metal-promoted hydroboration of alkenes: A unique reversal of regioselectivity
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When hydroboration of 1-octene is carried out in the presence of catalytic amounts of rhodium trichloride followed by the usual oxidation (hydrogen peroxide in aqueous alkali), only minor proportions of 1-octanol (2.4%) are formed accompanied by very significant amounts of 2- (17.4%), 3- (36.9%), and 4-octanol (43.3%). These product compositions are obtained in good overall yield when the borane-THF complex is slowly added to a stirred solution of 1-octene in THF solvent containing the rhodium trichloride. Isomerization of 1-octene to 2-, 3-, and 4-octene in the presence of rhodium trichloride alone is far too slow to account for the foregoing results. The mechanism likely involves multiple and reversible addition/elimination of a Rh-activated B-H species across the double bonds.
- Morrill, Terence C.,D'Souza, Christopher A.,Yang, Lu,Sampognaro, Anthony J.
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p. 2481 - 2484
(2007/10/03)
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- Secondary isotope effects in dioxirane epoxidations. Concerted or step-wise mechanism?
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The inverse α- and β-secondary isotope effects found for the epoxidation reaction of dimethyl dioxirane (DMD) with alkenes support a non polar concerted mechanism.
- Angelis, Yiannis,Zhang, Xiaojun,Orfanopoulos, Michael
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p. 5991 - 5994
(2007/10/03)
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- Radical reactions in organoboron chemistry II - Inter- and intramolecular addition of carbon centered radicals to alkenylboranes
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The intermolecular addition of carbon centered radicals to alkenylboranes has been studied. The influence of the olefin and boron substituents on the reactivity and the regioselectivity was determined. Competitive experiments were carried out to estimate the relative reactivity of a series of vinylboranes and other electron deficient alkenes. Intramolecular versions of these additions were also described as well as some further transformations of selected adducts.
- Guennouni,Lhermitte,Cochard,Carboni
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p. 6999 - 7018
(2007/10/02)
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- Evidence for Electron Transfer, Radical and Ionic Pathways in the Decomposition of Diacyl Peroxide
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The thermal decomposition mechanism of 4,4-dimethylpentanoyl m-chlorobenzoyl peroxide and its α- and β-dideuteriated analogues is described.Product analyses and CIDNP studies suggest that all three pathways, electron transfer, radical and ionic, are operative in decomposition of these peroxides.Two pulsed-NMR techniques have been employed to eliminate distortions of CIDNP intensities arising from spin-lattice relaxation.These quantitative CIDNP studies have revealed an additional pure ionic pathway which competes with the radical pair electron transfer pathway to form rearranged reaction products.
- Lee, Sueg-Geun
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p. 1361 - 1372
(2007/10/02)
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- Synthesis and antiallergy activity of [1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]pyrimidin-9(3H)-one derivatives. II. 6-Alkyl- and 6-cycloalkylalkyl derivatives
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A series of 6-alkyl- or 6-(cycloalkylalkyl)-[1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]pyr imidin-9(3H)-ones 1b-o was synthesized from the corresponding 1,3,4-thiadiazol-5-amines 3b-o and the antiallergic activities of the products were evaluated. Among the compounds 6-(2-cyclohexylethyl)-[1,3,4]thiadiazolo[3,2-a]-1,2,3-triazolo[4,5-d]p yrimidin-9(3H)-one 1h, whose X-ray crystallographic stereostructure is shown, was found to be a promising new antiallergic agent, which has low toxicity and dual activity as a leukotriene D4 receptor antagonist and as an orally active mast cell stabilizer.
- Yokohama,Miwa,Aibara,Fujiwara,Matsumoto,Nakayama,Iwamoto,Mori,Moroi,Tsukada,Isoda
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p. 2391 - 2398
(2007/10/02)
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- Shape Selective Alkane Hydroxylation by Metalloporphyrin Catalysts
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A series of manganese and iron porphyrins with sterically protected pockets are shown to be shape selective alkane hydroxylation catalysts.With iodosobenzene as oxidant, good regioselectivity is observed for hydroxylation of alkanes at the least hindered methyl group by using the very sterically hindered (5,10,15,20-tetrakis(2',4',6'-triphenylphenyl)porphyrinato)manganese(III) acetate (MnTTPPP(OAc)) as catalyst; The moderately hindered (5,10,15,20-tetrakis(2',4',6'-trimethoxyphenyl)porphyrinato)manganese(III) acetate shows little selectivity toward terminal CH3 hydroxylation but does show enhancement for the adjacent, ω - 1, CH2 site.Primary selectivity is dependent on the size and shape of the alkane substrate, with more bulky substituents giving greater primary selectivity.Substituting pentafluoroiodosobenzene or m-chloroperbenzoic acid as oxidants yields similar selectivity, thus conclusively demonstrating metal based oxidation via a common intermediate for these three systems.In contrast, tert-butyl hydroperoxide or 2,2,2-trifluoroethanol solubilized pentafluoroiodosobenzene show no primary carbon selectivity, and reaction product ratios are independent of the metalloporphyrin catalyst; this demonstrates that the site of oxidation with these oxidants is not metal based.The iron porphyrin derivatives also show good primary selectivity, although to a lesser degree than with the Mn derivatives, proving that these oxidations too are metal based.The regioselectivities for alkane hydroxilation shown by TTPPP derivatives are comparable to or better than those found for some isozymes of cytochrome P-450 which are responsible for primary alcohol biosynthesis from steroids, fatty acids, and alkanes.
- Cook, Bruce R.,Reinert, Thomas J.,Suslick, Kenneth S.
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p. 7281 - 7286
(2007/10/02)
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- Shape-selective Alkane Hydroxylation
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A series of sterically hindered manganese porphyrins have been used to catalyse shape-selective alkane hydroxylation, increasing the production of primary alcohols.
- Suslick, Kenneth,Cook, Bruce,Fox, Mary
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p. 580 - 582
(2007/10/02)
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- Process for the production of pure neohexanol
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For the production of neohexanol with a purity above 99%, a chlorine content of less than 10 ppm, and a sulfur content of less than 5 ppm, 3,3-dimethylbutyric acid with a chlorine content below 650 ppm, preferably below 100 ppm, is first esterified, optionally after distillatory separation into a portion richer in chlorine with a chlorine content above 650 ppm, preferably above 100 ppm, and into a portion low in chlorine with a chlorine content below 650 ppm, preferably below 100, with an alcohol boiling above 117° C., preferably an octyl alcohol. The resultant ester is separated by distillation into fractions richer in chlorine with chlorine contents above 10 ppm and into fractions low in chlorine with chlorine contents below 10 ppm. The ester of low chlorine contents below 10 ppm is hydrogenated to neohexanol over a barium-activated copper chromite catalyst under a pressure of 200-300 bar, at 120°-22° C., and with catalyst loads of 0.05-1.0 liter of hydrogenation feed/liter of catalyst . hour. The high purity of the neohexanol permits catalytic dehydrogenation to neohexanal.
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- Effects of Volume and Surface Property in Hydrolysis by Acetylcholinesterase. The Trimethyl Site
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β-Substituted ethyl acetates, XCH2CH2OCOCH3, have been prepared, and their hydrolysis by acetylcholinesterase has been studied.Log of enzymic reactivity, normalized for intrinsic reactivity in hydrolysis by hydroxide, log(kcat/Km)n, rises linearly with increasing refraction volume, MR (or RD25), for substrates with β-X = H, Cl, Br, CH3CH2, (CH3)2CH, (CH3)2S+, (CH3)3N+, and (CH3)3C.Larger substituents may by accommodated, (CH3)3Si and (CH3CH2)3N+, with no further increase in rate.Substrates with β-substituents CH3S, CH3S(O), (CH3)3N+(OH), and CH3S(O2) are less reactive than consistent with the relation with MR by factors of 5-40, indicating that hydrophobic surface and desolvation of the substrate-enzyme interface may be necessary for maximum reactivity correlated with MR.Values of log (kcat/Km)n for substrates with β-substituents X = CH3S, Cl, Br, CH3CH2, (CH3)2CH, (CH3)3C, and (CH3)3Si rise linearly with increasing hydrophobicity, ?, but reactivity of substrates with X = (CH3)3N+ and (CH3)2S+ are more reactive than consistent with a relation to ? by factors of 300 and 40 and with X = CH3S(O2), CH3S(O), and (CH3)2N+(OH), by factors of 7-100.Reactivity appears related to (i) volume of the β-substituent and its fit in its subsite, which is trimethyl rather than anionic, and (ii) the hydrophobicity of its surface.
- Cohen, Saul G.,Elkind, Jerome L.,Chishti, S. Bano,Giner, Jose-L. P.,Reese, Heide,Cohen, Jonathan B.
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p. 1643 - 1647
(2007/10/02)
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- 2,4-Dioxa-, 2,4,9-Trioxa-, 2,4-Dioxa-9-aza-, 2-Oxa-4,9-diaza-, and 2,4,9-Triazaadamantanes
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The reaction of the trihalides 7a, b with sodium cyanide in dimethylformamide afforded the cyclopropanedicarbonitrile 9 instead of of the tricarbonitrile 7c which had been designed as a precursor to 2,4,9-triazaadamantanes.Both the photolysis and thermolysis of the remarkably stable triazide 13c proceeded in an ill-defined way, producing unidentifiable products among which neither the triazaadamantane 6a nor hydrolysis products of the triimine 14 could be detected.The readily cyclizing triketone 3l was obtained from the reaction of the tricarbonyl chloride 3k with an excess of lithium dimethylcuprate followed by careful work-up.It proved to be the key to several novel heteroadamantanes: Thus, methoxide brought about an intramolecular aldol addition and cyclization of 3l to the 2,4-dioxaadamantane 15.An excess of liquid ammonia converted 3l into the 2,4-dioxa-9-azaadamantane 16a almost quantitatively.The same ring system (16b) was formed in the reaction of 3l with 12 mol of hydrazine hydrate.In contrast, the reaction of 3l with a very large excess of hydrazine hydrate afforded the 2-oxa-4,9-diazaadamantane 16c.Finally, 3l reacted with dry hydrazine in ethanol to yield the 2,4,9-triazaadamantane 16d.The structures of the new compounds were established by IR and NMR spectroscopy.Analysis of the complex 1H NMR multiplets of the methylene protons of 15 and 16a - c by LAOCOON III shows that they arise exclusively from W-couplings of 2 - 3 Hz and geminal couplings.
- Quast, Helmut,Berneth, Claus-Peter
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p. 1345 - 1363
(2007/10/02)
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- Solvomercuration-Demercuration. 10. Oxymercuration-Demercuration of Olefins with the Mercuric Salts Acetate, Trifluoroacetate, Nitrate, and Methanesulfonate
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The oxymercuration-demercuration of a series of representative olefins has been examined with four mercuric salts: acetate, trifluoroacetate, nitrate, and methanesulfonate.Mono- and 1,2-disubstituted olefins undergo hydration with all four mercuric salts in 90-100percent yields with a regioselectivity for the Markovnikov alcohol (from monoolefins) of >99.5percent.Only styrene was found to be an exception.In marked contrast, only mercuric acetate is effective for the Markovnikov hydration of 1,1-di-, tri- ,and tetrasubstituted olefins.The other three mercuric salts provide loweryields of the tertiary alcohols, yields which decrease rapidly with time. 1-Phenylcyclopentene undergoes only allylic oxidation with the mercuric salts trifluoroacetate, nitrate, and methanesulfonate.Mercuric acetate does give the normal hydration product but only in trace amounts.In this case, allylic oxidation is the major reaction pathway with this salt as well.
- Brown, Herbert C.,Geoghegan, Philip J.,Kurek, Joseph T.
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p. 3810 - 3812
(2007/10/02)
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