- Enantioselective Tail-to-Head Cyclizations Catalyzed by Dual-Hydrogen-Bond Donors
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Chiral urea derivatives are shown to catalyze enantioselective tail-to-head cyclization reactions of neryl chloride analogues. Experimental data are consistent with a mechanism in which ?-participation by the nucleophilic olefin facilitates chloride ionization and thereby circumvents simple elimination pathways. Kinetic and computational studies support a cooperative mode of catalysis wherein two molecules of the urea catalyst engage the substrate and induce enantioselectivity through selective transition state stabilization.
- Kutateladze, Dennis A.,Strassfeld, Daniel A.,Jacobsen, Eric N.
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p. 6951 - 6956
(2020/05/19)
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- Upcycling a plastic cup: One-pot synthesis of lactate containing metal organic frameworks from polylactic acid
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Waste PLA can be upcycled to metal organic frameworks of potential high value in a one-pot synthesis scheme, where PLA depolymerisation occurs in situ. Three homochiral lactate based frameworks were successfully synthesised and characterised from PLA as a feed source, including ZnBLD. The chiral separation ability of ZnBLD was maintained.
- Slater, Benjamin,Wong, So-On,Duckworth, Andrew,White, Andrew J. P.,Hill, Matthew R.,Ladewig, Bradley P.
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supporting information
p. 7319 - 7322
(2019/06/27)
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- Thermal Behavior Analysis of Two Synthesized Flavor Precursors of N-alkylpyrrole Derivatives
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To expand the library of pyrrole-containing flavor precursors, two new flavor precursors—methyl N-benzyl-2-methyl-5-formylpyrrole-3-carboxylate (NBMF) and methyl N-butyl-2-methyl-5-formylpyrrole-3-carboxylate (NUMF)—were synthesized by cyclization, oxidation, and alkylation reactions. Thermogravimetry (TG), differential scanning calorimeter, and pyrolysis–gas chromatography/mass spectrometry were utilized to analyze the thermal degradation behavior and thermal degradation products of NBMF and NUMF. The TG-DTG curve indicated that the maximum mass loss rates of NBMF and NUMF appear at 310 and 268°C, respectively. The largest peaks of NBMF and NUMF showed by the differential scanning calorimeter curve were 315 and 274°C, respectively. Pyrolysis–gas chromatography/mass spectrometry detected small molecule fragrance compounds appeared during thermal degradation, such as 2-methylpyrrole, 1-methylpyrrole-2-carboxylic acid methyl ester, limonene, and methyl formate. Finally, the thermal degradation mechanism of NBMF and NUMF was discussed, which provided a theoretical basis for their application in tobacco flavoring additives.
- Ai, Lvye,Liu, Mengzhen,Ji, Xiaoming,Lai, Miao,Zhao, Mingqin,Ren, Tianbao
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p. 2389 - 2397
(2019/08/01)
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- Synthesis of Trisubstituted Alkenyl Boronic Esters from Alkenes Using the Boryl-Heck Reaction
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The direct borylation of disubstituted alkenes is reported. These conditions allow for the conversion of a variety 1,1- and 1,2-disubstituted alkenes to trisubstituted alkenyl boronic esters with outstanding yields and excellent E/Z selectivities. The utility of this reaction has been demonstrated with several downstream functionalization reactions, which allow access to diverse, stereodefined, functionalized olefins. Mechanistic studies are consistent with a boryl-Heck pathway.
- Reid, William B.,Watson, Donald A.
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supporting information
p. 6832 - 6835
(2018/10/24)
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- Photocatalytic Transfer Hydrogenolysis of Allylic Alcohols on Pd/TiO2: A Shortcut to (S)-(+)-Lavandulol
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We report herein a regio- and stereoselective photocatalytic hydrogenolysis of allylic alcohols to form unsaturated hydrocarbons employing a palladium(II)-loaded titanium oxide; the reaction proceeds at room temperature under light irradiation without stoichiometric generation of salt wastes. Olefin and saturated alcohol moieties tolerated the reaction conditions. Hydrogen atoms were selectively incorporated into less sterically congested carbons of the allylic functionalities. This protocol allowed a short-step synthesis of (S)-(+)-lavandulol from (R)-(?)-carvone by avoiding otherwise necessary protection/deprotection steps.
- Takada, Yuki,Caner, Joaquim,Kaliyamoorthy, Selvam,Naka, Hiroshi,Saito, Susumu
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supporting information
p. 18025 - 18032
(2017/12/08)
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- Photocaged Hydrocarbons, Aldehydes, Ketones, Enones, and Carboxylic Acids and Esters that Release by the Norrish II Cleavage Protocol and Beyond: Controlled Photoinduced Fragrance Release
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Five families of caged fragrance compounds that allow the storage and release of the following small volatile organic molecules are described: terpene hydrocarbons, aldehydes, ketones, Michael-type α,β-unsaturated enones, and carboxylic acids and esters. These caged molecules are released by photoexcitation via carbonyl-directed hydrogen-transfer processes and subsequent C-C bond cleavage (Norrish Type II) or by didenitrogenation of diazirines.
- Griesbeck, Axel G.,Porschen, Bj?rn,Kropf, Christian,Landes, Agnieszka,Hinze, Olga,Huchel, Ursula,Gerke, Thomas
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p. 539 - 553
(2017/01/25)
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- Acidic functionalized ionic liquids as catalyst for the isomerization of α-pinene to camphene
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An acidic functionalized ionic liquids (ILs) [HSO3-(CH2)3-NEt3]Cl-ZnCl2 was synthesized and used to catalyze the isomerization of α-pinene in a homogeneous system. The optimum conditions for isomerization were obtained as follows: n(α-pinene):n(ILs) = 9:1, reaction temperature 140 °C, and reaction time 4 h, α-pinene 0.04 mol. Under the optimal conditions, the conversion of α-pinene was 97.6 % and the selectivity for camphene could reach 64.8 %. In addition, the catalyst could be easily separated by centrifugation after the isomerization completely finished. When the ILs were repeatedly used for four times, the conversion of α-pinene and the selectivity for camphene were still excellent, indicating the superb recycle ability of the acidic functionalized ILs catalyst.
- Liu, Yue,Li, Lu,Xie, Cong Xia
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p. 559 - 569
(2016/04/26)
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- Metal-organic framework Co(D-cam)1/2(bdc)1/2(tmdpy) for improved enantioseparations on a chiral cyclodextrin stationary phase in gas chromatography
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Initial efforts to combine a chiral metal-organic framework (MOF), Co(D-Cam)1/2(bdc)1/2(tmdpy) (D-Cam=D-camphoric acid, bdc=1,4-benzenedicarboxylic acid, tmdpy=4,4′-trimethylenedipyridine), with peramylated β-cyclodextrins to investigate whether the use of a MOF can enhance enantioseparations on a cyclodextrin stationary phase are reported. Compared with columns of peramylated β-cyclodextrin incorporated in a MOF containing sodium chloride, the column of peramylated β-cyclodextrin+MOF shows excellent selectivity for the recognition of racemates, and higher resolutions are achieved on the peramylated β-cyclodextrin+MOF stationary phase. Experimental results indicate that the use of Co(D-Cam) 1/2(bdc)1/2(tmdpy) can improve enantioseparations on peramylated β-cyclodextrins. This is the first report that chiral MOFs can improve enantioseparations on a chiral stationary phase for chromatography. Copyright
- Liu, Hong,Xie, Sheng-Ming,Ai, Ping,Zhang, Jun-Hui,Zhang, Mei,Yuan, Li-Ming
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p. 1103 - 1108
(2014/11/07)
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- Aromas Kit
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An Aromas kit uses containers of certain discrete molecules to provide odors suitable for an olfactory education of wine properties. The disclosed molecules may be found within certain wines and provide a useful olfactory reference when smelling a finished wine sample, even when the wine sample contains a myriad of other conflicting or competing molecule smells.
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- Kinetics of thermal conversions of monoterpenic compounds in supercritical lower alcohols
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The most important information concerning thermal conversions of vegetable terpenes (α-pinene, β-pinene, turpentine, and cis-verbenol) in supercritical lower alcohols is systematized. The kinetics of selected reactions is reported and is compared with the kinetics of the same reactions in the gas and liquid phases. Thermodynamic calculations of the phase states and kinetic parameters are presented for a number of multicomponent multiphase systems containing terpenes and lower alcohols. The effect of the supercritical solvent pressure on the rate and selectivity of the selected reactions is reported.
- Anikeev,Ermakova,Chibiryaev,Kozhevnikov
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scheme or table
p. 162 - 193
(2010/09/04)
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- Supported gold and silver nanoparticles for catalytic deoxygenation of epoxides into alkenes
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Taking the 'O': Supported gold and silver nanoparticles (NPs), which are wellknown epoxidation catalysts, were found to have intrinsic catalytic ability for the deoxygenation of epoxides into alkenes using alcohol as a reductant (see picture). The selectivity for all the alkenes were over 99%, and an excellent turnover number was achieved. Furthermore, these supported gold and silver nanoparticles were recyclable. Figure Presented
- Mitsudome, Takato,Noujima, Akifumi,Mikami, Yusuke,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information; scheme or table
p. 5545 - 5548
(2010/09/05)
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- Biotransformation of one monoterpene by sporulated surface cultures of Aspergillus niger and Penicillium sp.
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In this study, biotransformation of menthol by sporulated surface culture of Aspergillus niger and Penicillium sp. was studied. The main bioconversion product obtained from menthol of A. niger was cis-p-menthan-7-ol and the main products obtained by surfa
- Esmaeili, Akbar,Sharafian, Shirin,Safaiyan, Shila,Rezazadeh, Shamsali,Rustaivan, Abdolhossein
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experimental part
p. 1058 - 1061
(2010/08/19)
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- The kinetics, stereochemistry, and deuterium isotope effects in the α-pinene pyrolysis. Evidence for incursion of multiple conformations of a diradical
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Pyrolysis of optically active α-pinene gave 95% racemic limonene (dipentene), alloocimine, racemic α-pinene, α-pyronene. Activation parameters are reported. Pyrolysis of (S) syn-6-trideuteriomethyl α-pinene at 256.7°C for 2400s gave dipentene with twice as much deuterium as hydrogen transfer with kH/kD=1.49 and alloocimine with a Z and E trideuteriomethyl ratio of ca. 5 with kH/kD=0.89. The isotope effect on loss of starting material was 1.16. Separation of the enantiomers of α-pinene from 3600s pyrolyses at 256.7°C followed by NMR analysis revealed that the ratio of the R-syn to R-anti to S-anti isomers is 4.6:3.7:1 at roughly two half-lives. Kinetic analysis reveals that the previously proposed mechanism for all conversions involving slow interconversion of two diradicals with Cs symmetry is not consistent with the distribution of the ??-pinene isomers, particularly the formation of more suprafacial-retention product (R-anti) than bond-rotated isomer (S-anti). Inclusion of another Cs species (ignoring the deuteriums) that would be intermediate between the originally proposed Cs species, appears more consistent with the observations.
- Gajewski, Joseph J,Kuchuk, Ilya,Hawkins, Christopher,Stine, Robert
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p. 6943 - 6950
(2007/10/03)
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- Lewis acid-activated chiral leaving group: Enantioselective electrophilic addition to prochiral olefins
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A new strategy using a BINOL derivative as a chiral leaving group and Lewis acid has been developed for enantioselective alkylation of prochiral olefins. (R)-2,2′-Bis[2-(trimethylsilyl)ethoxy- methyl]-1,1′-binaphthol is demonstrated to be an effective reagent for enantioselective hydroxymethylation of silyl enol ethers and trisubstituted alkenes. Electrophilic addition to prochiral olefins is accompanied by cleavage of an acetal that is dual activated by SnCl4 and the δ-effect of silicon through the SN2 substitution process. Enantioselective synthesis of cyclic terpenes is also described using this strategy.
- Nakamura, Hiroko,Ishihara, Kazuaki,Yamamoto, Hisashi
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p. 5124 - 5137
(2007/10/03)
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- Asymmetric synthesis of (R)-limonene and (S)-cembrene-A by an intramolecular cyclization reaction using a chiral leaving group
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A six-membered monocyclic terpene, (R)-limonene, and a 14-membered monocyclic diterpene, (S)-cembrene-A, have been synthesized, respectively, by new enantioselective intramolecular cyclization reactions of neryl ether and (all-E)-geranylgeranyl ether using an (R)- 1,1′-binaphthyl-2-benzoxy-2′-oxy auxiliary as a chiral leaving group in the presence of tin(IV) chloride.
- Ishihara,Nakamura,Yamamoto
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p. 1113 - 1116
(2007/10/03)
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- 2,3-dioxabicyclo[3.3.1]nonane derivatives and antimalarial pharmaceutical compositions comprising them
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PCT No. PCT/IL98/00440 Sec. 371 Date May 11, 2000 Sec. 102(e) Date May 11, 2000 PCT Filed Sep. 10, 1998 PCT Pub. No. WO99/12900 PCT Pub. Date Mar. 18, 19992,3-Dioxabicyclo[3.3.1]nonane derivatives, carrying, at position 4, a sulfur-containing functionality selected from the group consisting of sulfonyl, sulfinyl and sulfenyl, adhered to C(4) vie methylene group, represented by structural formula (A) wherein: X is hydrogen, hydroxy, alkoxy, optionally substituted by alkoxy or acyloxy, aralkoxy optionally substituted by alkoxy or aryloxy, and M is hydrogen, hydroxy, alkoxy, alkenyloxy, acyloxy, optionally substituted by acyl or acyloxy, aralokoxy, arylalkenyloxy, oxalyloxy substituted by alkoxy, di(alkyl)amino or alkyl(aryl)amino, di(aralalkyl)amino or carbonyloxy substituted by arloxy, di(alkyl)amino, di(aralkyl)amino and alkyl(aryl)amino; or X and M together represent a carbon-carbon bond or an oxygen atom; L is hydrogen or L and M together represent a carbon-carbon bond; and either Z is a radical R-S(=O)n- and Y is hydrogen, or Y is R-S(=O)n- and Z is hydrogen, wherein R is alkyl optionally substituted by alkoxy or alkoxycarbonyl, cycloalkyl, or aryl or araklkyl optionally substituted by alkyl, halogen or CF3; and n is 0, 1, or 2, are useful for the prevention and/or treatment of malaria.
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- An efficient method for the reductive transposition of allylic alcohols
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The Mitsunobu reaction of allylic alcohols with o- nitrobenzenesulfonylhydrazine (NBSH) as nucleophile proceeds at -30 °C with invertive displacement; warming the resultant N-allylic sulfonylhydrazine derivative to 23 °C then leads to allylic diazene formation followed by sigmatropic elimination of dinitrogen. This one-step method for reductive 1,3-transposition is shown to be efficient and highly regio- and stereocontrolled within a wide range of allylic alcohol substrates.
- Myers, Andrew G.,Zheng, Bin
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p. 4841 - 4844
(2007/10/03)
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- 1,2-Dipolar-Cycloaddition of Benzylazide to (+)-Limonene: A Protection Cycle for the 8,9-Double Bond.
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A method for protecting the 8.9-double bond of (+)-limonene (1) is described.The key step is the 1,3-dipolar-cycloaddition of benzylazide to 1, which affords N-benzyl-N--amine (2) and N-benzyl-N--amine (3).
- Oliveira de, Denilson Ferreira,Kover, Warner Bruce
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p. 1799 - 1802
(2007/10/02)
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- Selective Deoxygenation of Allylic Alcohols and Acetates by Lithium Perchlorate Promoted Triethylsilane Reduction
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A series of cyclic secondary allylic alcohols and acetates was deoxygenated using triethylsilane in the presence of ethereal lithium perchlorate.Under these conditions the allylic oxygen functionality was selectively removed in the presence of esters, isolated olefins, ketals and tertiary alcohols.Primary allylic alcohols were not deoxygenated under these conditions.
- Wustrow, David J.,Smith, William J.,Wise, Lawrence D.
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- Enantioselective Terpene Syntheses by Diels-Alder Reaction of 1-(1-Arylalkoxy)-2-methyl-1,3-butadiene with Isoprene
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The (R)- and (S)-1-(1-arylalkoxy)-2-methyl-1,3-butadienes 6 undergo cycloadditions with excess isoprene (7) under pressure to yield not only the expected (4S,6R)- and (4R,6S)-trans-carveol (8) with up to 96percent e.e. but also up to 40percent of (R)- and (S)-limonene (9) with up to 93percent e.e.Asymmetric induction is proposed to arise from a transition state involving definite ? stacking of one molecule of isoprenyl ether and two molecules of isoprene.Key Words: (4S,6R)-, (4R,6S)-trans-Carveol / (R)-, (S)-Limonene / Isoprene / Isoprenyl ether / Cycloaddition, diastereo-, enantioselective
- Zadel, Guido,Rieger, Rainer,Breitmaier, Eberhard
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p. 1343 - 1346
(2007/10/02)
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- Reductive Deoxygenation of α,β-Unsatured Ketones via Cyanophosphates by Lithium in Liquid Ammonia
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A new method for deoxygenation of α,β-unsatured ketones via cyanophosphates by lithium metal in liquid ammonia is described
- Yoneda, Ryuji,Osaki, Hirotaka,Harusawa, Shinya,Kurihara, Takushi
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p. 2817 - 2818
(2007/10/02)
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- Synthesis and Absolute Configuration of (-)-Furodysinin. New Transformations of Camphor Derivatives
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The synthesis of (-)-furodysinin ((-)-3a) has been accomplished in five steps from (+)-?--bromocamphor (7) and has allowed assignment of the absolute configuration of a number of marine furanosesquiterpenes produced by sponges of the genus Dysidea.
- Richou, Olivier,Vaillancourt, Valerie,Faulkner, D. John,Albizati, Kim F.
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p. 4729 - 4730
(2007/10/02)
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- A New Method for C-C Coupling of Terminal Alkenes via a Sulphonylation-Alkylation-Desulphinylation Sequence: Synthesis of E- and Z-α-Bisabolenes
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A new method for regiospecific C-C coupling of terminal alkenes based on a sulphonylation-alkylation-desulphinylation process, mediated through allylic sulphinic acids, and its application to the conversion of limonene into E- and Z-α-bisabolenes, are described.
- Baldwin, Jack E.,Adlington, Robert M.,Ichikawa, Yoshiyasu,Kneale, Christopher J.
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p. 702 - 704
(2007/10/02)
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- CHIRAL LEAVING GROUP: ASYMMETRIC SYNTHESIS OF LIMONENE AND BISABOLENE
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The biogenetic-type asymmetric synthesis of limonene and bisabolenes is described.As model studies for the present asymmetric synthesis, the cyclization of catechol, biphenol and binaphthol mononeryl ethers 1, 4, and 5, with organoaluminium reagents are executed to furnish limonene as a major product.Since the reaction of 1, 4, and 5 has proved to proceed much faster than that of neryl phenyl ether under the similar conditions, the rate acceleration is attributed to the novel metal-anchimeric assistance of the aluminium reagents bound with the neighboring hydroxyl group for effecting the generation of the allyl cathion.This anchimeric effect is utilized for the enantioselective cyclization of (R)-(+)-1,1'-bi-2-naphthol mononeryl ether (8) upon treatment with modified aluminium reagent 9 to produce limonene with high optical purity (77percent ee).In a similar fashion, (R)-(+)-binaphtol (Z,Z)-monofarnesyl ether 16a undergoes the enantioselective cyclization to give β-bisabolene in 76percent ee.
- Sakane, Soichi,Fujiwara, Junya,Maruoka, Keiji,Yamamoto, Hisashi
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p. 2193 - 2202
(2007/10/02)
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- Pesticides containing D-limonene
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Pesticide compositions are disclosed which contain D-limonene as an insect-killing ingredient along with surfactants or emulsifiers and water. The pesticide compositions are liquids designed for use as a flexible-purpose pesticide concentrate; a dip to rid small animals of fleas and ticks; a spray to kill fleas and ticks on small animals and in the kennels of small animals; a spray to kill flies on small animals and in the kennels of small animals; and a spray or liquid to rid household areas of cockroaches and other insect pests. The composition is non-toxic, non-polluting, biodegradable, non-irritating to animals other than insect pests.
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