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Hydrocarbons, Cyclic (3):
Recent article
Hydrocarbons, Cyclic
Abstract
The synthetic potential of stereoselective, palladium-catalyzed hydro(het)arylation reactions of bi-, tri- and tetracyclic (hetero)alkenes in the presence of phospines and arsines as highly efficient ligands was studied. The mechanism of this reductive Heck reaction becomes more complex in the case...
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PMID: 20657489
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PDF is available here.
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Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment and General Theory (114)12 2010
Abstract
We employ many-body electronic structure calculations to determine the energies and characters of the low-lying valence states of a minimal aryl peroxycarbonate model germane to the above-mentioned experiments, methyl phenyl peroxycarbonate (MPC). Our results indicate that the lowest-lying state is...
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PMID: 20201535
PDF is available here.
PDF is available here.
Abstract
Gossypol and cyclododecanone crystallize at room temperature as an inclusion complex in a 1:2 molar ratio. This complex, viz. 1,1',6,6',7,7'-hexahydroxy-5,5'-diisopropyl-3,3'-dimethyl-2,2'-binaphthalene-8,8'-dicarboxaldehyde2013cyclododecanone (1/2), C30H30O8·2C12H22O, is unusu...
PDF is available here.
PDF is available here.
Abstract
Abstract
A number of N-(arylcarbamothioyl)cyclohexanecarboxamide derivatives (aryl substituents: phenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, o-tolyl, p-tolyl, 3-methoxyphenyl, 4-methoxyphenyl and naphthalen-1yl) have been synthesized. The compounds obtained were characterized by elemental analyse...
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PMID: 19214154
PDF is available here.
PDF is available here.
Journal of Organic Chemistry (73)18 2008
Abstract
A series of planar tetracoordinate carbon molecules in cyclic semisaturated hydrocarbons resulting from the combination of the C5(2-) skeleton with saturated hydrocarbon fragments is reported. The electronic stabilization and the bonding situation are studied through the analyses of molecular orbita...
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PMID: 18642953
PDF is available here.
PDF is available here.
Abstract
Ten- and eleven-membered-ring cyclic enediynes that possess a carbonyl group in a beta position with respect to the one of acetylenic termini undergo very facile cycloaromatization at ambient temperatures. Kinetic data and deuterium-labeling experiments indicate that this reaction proceeds via rate-...
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PMID: 18693691
PDF is available here.
PDF is available here.
Journal of Organic Chemistry (73)17 2008
Abstract
Highly enantioselective catalytic intramolecular ortho-alkylation of aromatic imines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using [RhCl(coe)2]2 and chiral phosphoramidite ligands. Cyclization of substrates containing 1,1- and 1...
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PMID: 18681407
PDF is available here.
PDF is available here.
Abstract
We recently reported a difluorinated cyclooctyne (DIFO) reagent that rapidly reacts with azides in living cells without the need for copper catalysis. Here we report a novel class of DIFO reagents for copper-free click chemistry that are considerably more synthetically tractable. The new analogues m...
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PMID: 18680289
PDF is available here.
PDF is available here.
Abstract
A novel series of hetero-arylboroxines were synthesized and structurally characterized by X-ray diffraction, NMR and computational analysis. The solid-state structures of the hetero-arylboroxines represent the first report of AB(2)-type hetero-arylboroxines.
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PMID: 18629398
PDF is available here.
PDF is available here.
YAKUGAKU ZASSHI (128)8 2008
Abstract
We named this rearrangement epoxysilane rearrangement. Based on results of mechanistic studies involving competitive experiments using diastereomeric cyanohydrins, we propose a reaction pathway involving a silicate intermediate formed by a concerted process via an anti-opening of the epoxide followe...
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PMID: 18670182
PDF is available here.
PDF is available here.
Abstract
New strategies using chiral acetal or chiral mixed-acetal in the presence of Lewis acids (SnCl4 or TiCl4) to promote polyene cyclization reaction are described. Acetal-promoted and mixed-acetal-promoted polyene cyclization products are very versatile and can easily be converted into various opticall...
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PMID: 18605726
PDF is available here.
PDF is available here.
Abstract
Bifunctional, fluorinated cyclooctynes were used for the in situ "click" crosslinking of azide-terminated photodegradable star polymers, yielding photodegradable polymeric model networks with well-defined structures and tunable gelation times.
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PMID: 18688349
PDF is available here.
PDF is available here.
Abstract
A series of aluminium alkyl complexes (BDI)AlEt(2) (3a-m) bearing symmetrical or unsymmetrical beta-diketiminate ligand (BDI) frameworks were obtained from the reaction of triethyl aluminium and the corresponding beta-diketimine. The monomeric structure of the aluminium complex 3k was confirmed by a...
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PMID: 18560667
PDF is available here.
PDF is available here.
Journal of Organic Chemistry (73)13 2008
Abstract
A molecular basket, composed of a semirigid C3v symmetric tris-norbornadiene framework and three pyridine flaps at the rim, has been shown to coordinate to a Cu(I) cation and thereby fold in a multivalent fashion. The assembly was effective (Ka = 1.73 +/- 0.08 x 10(5) M(-1)) and driven by enthalpy (...
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PMID: 18522422
PDF is available here.
PDF is available here.
Journal of Organic Chemistry (73)13 2008
Abstract
Pyrrole 2-carboxylic acid (L5) was found to be an effective ligand for the Cu-catalyzed monoarylation of anilines with aryl iodides and bromides. Under the reported conditions (10% CuI/20% L5/DMSO/K3PO 4/80-100 degrees C/20-24 h), a variety of useful functional groups were tolerated, and moderate to...
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PMID: 18543973
PDF is available here.
PDF is available here.
Abstract
We have applied this domain-selection scheme to a series of chiral molecules, including pseudo-linear structures (hydrogen molecule helices, fluoroalkanes, and [n]triangulanes), cage-like structures (beta-pinene, methylnorbornanone, and bisnoradamantan-2-one), and aromatic rings (1-phenylethanol). W...
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PMID: 18535716
PDF is available here.
PDF is available here.
Abstract
The intramolecular cycloaddition of 1,n-diene-ynes (n = 4-6), where alkyne and alkene moieties are connected by a 1,1-disubstituted alkene, was examined using a chiral rhodium catalyst, and various types of cycloadducts with quaternary carbon stereocenter(s) were obtained in high to excellent enanti...
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PMID: 18293972
PDF is available here.
PDF is available here.
Inorganic Chemistry (47)4 2008
Abstract
P-bound derivatives of the hypophosphorous acids can be prepared from complexed phosphinidene oxides. The anion [MoCp(CO) 2{P(O)R*}] (-)[(H-DBU) (+) salt (R* = 2,4,6-C 6H 2 (t)Bu 3; Cp = eta (5)-C 5H 5) reacts with SnCl 2Ph 2 to give the neutral oxophosphinidene complex [MoCp{P(O)R*}(CO) 2(SnPh 2Cl)...
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PMID: 18225856
PDF is available here.
PDF is available here.
Abstract
Abstract
Maps of current density induced by a perpendicular external magnetic field are calculated at the ipsocentric CTOCD-DZ/6-31G**//B3PW91/6-31G** level for ring carbo-mers of [N]-annulenes (closed-shell singlet states of C(3N)H, N = 3 to 7, with q = -1, 0, +1, 0, -1, respectively, and also the triplet g...
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PMID: 18259634
PDF is available here.
PDF is available here.
Chemosphere (70)11 2008
Abstract
A novel strategy utilizing the phenyls interaction and the hydrophobic affinity of available siloxane surface in the interlayer of bentonite was proposed to improve the sorption capabilities of organobentonites for water soluble aromatic contaminants. A unique organobentonite (65BTMA) was synthesize...
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PMID: 17983640
PDF is available here.
PDF is available here.
Abstract
Although oxidations of aromatic amines by horseradish peroxidase (HRP) are well-known, typical aliphatic amines are not substrates of HRP. In this study, the reactions of N-benzyl and N-methyl cyclic amines with HRP were found to be slow, but reactions of N-(3-indoleethyl) cyclic amines were 2-3 ord...
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PMID: 18163622
PDF is available here.
PDF is available here.
Bioconjugate Chemistry (19)1 2008
Abstract
We describe a versatile bifunctional chelator, DO3A-VS (1,4,7-tris(carboxymethyl)-10-(vinylsulfone)-1,4,7,10-tetraazacyclododecane) that binds a range of radiometals including 111 In for gamma-ray imaging and 64Cu for positron emission tomography (PET), and which can be conjugated with negligible lo...
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PMID: 17988078
PDF is available here.
PDF is available here.
Abstract
A novel enantioselective total synthesis of the oral contraceptive desogestrel (2) is described, in which the tetracyclic steroid core is formed by a sequence of two consecutive Heck reactions. Conversion of the known enantiopure diketone 7 led to the chiral bicycle 6 which was used for a diastereos...
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PMID: 18038382
PDF is available here.
PDF is available here.
Abstract
Abstract
An efficient method for the soluble polymer-supported synthesis of 5-arylidene thiazolidinones and pyrimidinones using aniline as a traceless linker was described. Aldehyde substrates were attached to the polyethylene glycol (PEG)-bound aniline via an imine linkage, and after the subsequent PEG-prom...
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PMID: 18642887
PDF is available here.
PDF is available here.
Abstract
Abstract
Journal of Organic Chemistry (72)26 2007
Abstract
DFT calculations have been performed to study the course of dichlorocarbene insertion reactions into alkanes and to better understand the regio- and stereoselectivities observed. At the B3LYP/6-31G(d) level of theory, the selectivity of dichlorocarbene insertions into a number of hydrocarbons agrees...
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PMID: 18047374
PDF is available here.
PDF is available here.
Journal of Organic Chemistry (72)25 2007
Abstract
Homologues of kainic acid, a naturally occurring potent glutamate receptor agonist, were designed based on a rigidified pipecolinoglutamic acid structure and can be regarded as homokainoids for their potential activities in the central nervous system. These novel homokainoids in an enantiomerically...
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PMID: 17999516
PDF is available here.
PDF is available here.
Abstract
The macrocycles 1,4,7-tris(carbamoylmethyl)-1,4,7,10-tetrazacyclododecane (1), 1,4,7-tris[(N-ethyl)carbamoylmethyl]-1,4,7,10-tetraazacyclododecane (2), 1,4,7-tris[(N,N-diethyl)carbamoylmethyl]-1,4,7,10-tetraazacyclododecane (3) and their Eu(III) complexes are prepared. Studies using direct Eu(III) e...
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PMID: 17985025
PDF is available here.
PDF is available here.
Abstract
We report a computational investigation of the conformation and the dynamics of self-assembled monolayers (SAMs) of a set of aromatic thiols arranged in the ( radical3 x radical3)-R30 degrees packing ratio on a Au(111) surface using molecular dynamics (MD) simulations. It was found that the molecula...
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PMID: 17958384
PDF is available here.
PDF is available here.
Journal of Organic Chemistry (72)24 2007
Abstract
A simple and highly effective C-O(carboxylic) coupling reaction catalyzed by copper(I) salts has been developed to synthesize benzopyranones. The reaction of various 2-halobiarylcarboxylic acids was examined using microwave irradiation. A new class of pyrroloisoquinoline alkaloid, isolamellarin, was...
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PMID: 17975927
PDF is available here.
PDF is available here.
Abstract
A deep, water-soluble cavitand extracts a variety of neutral hydrophobic species into its cavity. Flexible species such as n-alkanes tumble rapidly on the NMR time scale inside the cavity, but this motion is slowed for bulkier guests. Long, rigid guests such as p-substituted aromatics are either sta...
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PMID: 17927175
PDF is available here.
PDF is available here.
Abstract
Abstract
A microwave-enhanced, palladium-catalyzed protocol for the alpha-arylation of a protected glycine in neat water is described. This reaction proceeds rapidly, under non-inert conditions, to afford a range of phenylglycine derivatives in moderate to good yields. Based on this alpha-arylation, a number...
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PMID: 18478959
PDF is available here.
PDF is available here.
Abstract
We report a Cu-free variant of click chemistry that can label these biomolecules rapidly and selectively in living systems, overcoming the intrinsic toxicity of the canonical Cu-catalyzed reaction. The critical reagent, a substituted cyclooctyne, possesses ring strain and electron-withdrawing fluori...
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PMID: 17942682
PDF is available here.
PDF is available here.
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment and General Theory (111)42 2007
Abstract
The performance of a variety of DFT functionals (BLYP, PBE, B3LYP, B3P86, KMLYP, B1B95, MPWPW91, MPW1B95, BB1K, MPW1K, MPWB1K, and BMK), together with the ab initio methods RHF, RMP2, and G3(MP2)-RAD, and with ONIOM methods based on combinations of these procedures, is examined for calculating the e...
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PMID: 17887739
PDF is available here.
PDF is available here.
Natural Product Research (21)12 2007
Abstract
Chemical investigation on the organic extract of the gorgonian coral Ellisella robusta furnished two 11,20-epoxybriaranes 1 and 2. The structures of briaranes 1 and 2 were assigned on the basis of spectroscopic evidence. The natural products of this type (11,20-epoxybriarane) were found to be a chem...
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PMID: 17852744
PDF is available here.
PDF is available here.
Abstract
Abstract
A new series of optically pure 5-amino-2-substitutedphenyl-1,3-dioxacycloalkanes were designed and synthesized via a chemo-enzymatic combined method to develop new chemoprevention agents. Twenty-four of newly synthesized compounds significantly inhibited xylene-induced rat ear edema and exhibited co...
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PMID: 17609123
PDF is available here.
PDF is available here.
Abstract
Vicia faba was grown in crude oil polluted soil and its roots were extracted for the detection and estimation of hydrocarbons. Saturated and unsaturated Aliphatic Hydrocarbons (AHs) ranging from C(22) to C(36) were identified in AHs fraction. However, PAHs were not present in the same extract. This...
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PMID: 17180412
PDF is available here.
PDF is available here.
YAKUGAKU ZASSHI (127)9 2007
Abstract
We found that the use of enolate of 2-cycloheptenone instead of the enolates of alkenyl methyl ketone as the four-carbon unit in the [3+4] annulation produces bicyclo[3.3.2]- decenone derivatives, in which the two-atom internal tether could be cleaved to give the cis-3,4,8-trisubstituted cycloocteno...
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PMID: 17827921
PDF is available here.
PDF is available here.
Abstract
OBJECTIVE: To analyze components of volatile oil from the herb of Pimpinella candolleana. Method: The components of volatile oil were investigated by SPME-GC-MS. RESULT: Sixty-five compounds were identified which accounted for 92. 17% of total volatile oil. CONCLUSION: The main constituents in the e...
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PMID: 17992994
PDF is available here.
PDF is available here.
Journal of Organic Chemistry (72)14 2007
Abstract
Arylation of both acyclic ketones and primary and secondary amines was achieved using a new, simple, stable, and easy-to-access nickel(II)-halide complex bearing mixed PPh3/N-heterocyclic carbene ligands as a catalyst precursor. Acyclic ketones were first arylated at the alpha-position with the nick...
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PMID: 17559270
PDF is available here.
PDF is available here.
Abstract
The asymmetric Michael-type Friedel-Crafts reaction of naphthols and nitroolefins promoted by bifunctional thiourea-tertiary amine organocatalysts (up to 95% ee) was investigated; on simply extending the reaction time further cascade reactions could occur to generate enantiopure dimeric tricyclic 1,...
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PMID: 17534499
PDF is available here.
PDF is available here.
Abstract
Syntheses and antibacterial activity of 13-membered 1,3-phendioxy substituted cyclic enediynes are reported. The compounds were screened against gram-positive and gram-negative strains and some of the compounds exhibit potent antibacterial activity.
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PMID: 17433674
PDF is available here.
PDF is available here.
Abstract
We present a detailed analysis of the structural, infrared spectra and visible spectra of the 4-substituted aminoazo-benzenesulfonyl azides. The preparation of 4-sulfonyl azide benzenediazonium chloride with cyclic amines of various ring sizes (pyrrolidine, piperidine, 4-methylpiperidine, N-methylpi...
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PMID: 16965932
PDF is available here.
PDF is available here.
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment and General Theory (111)19 2007
Abstract
We have recently proposed that the addition of C2H2 to the cyclopentadienyl radical can lead to the rapid formation of the cycloheptatrienyl radical and, in succession, of the indenyl radical. These reactions represent an interesting and unexplored route for the enlargement of gas-phase cyclic speci...
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PMID: 17298043
PDF is available here.
PDF is available here.
Abstract
Addition of a stoichiometric amount of HCl to alkenylaldimines, -formamidines, and -amidines results in the protonation of the sp2-nitrogen atom. The resulting alkenylaldiminium, -formamidinium, and -amidinium salts can be isolated and fully characterized, including single-crystal X-ray diffraction...
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PMID: 17408289
PDF is available here.
PDF is available here.
Abstract
Several factors that contribute to the success of aldol cyclotrimerizations have been clarified as part of an effort to shed light on the inner workings of this century old reaction. The use of 4,7-di-tert-butylacenaphthenone (11) as a mechanistic probe molecule has led to intriguing discoveries abo...
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PMID: 17381158
PDF is available here.
PDF is available here.
Abstract
The aza-Morita-Baylis-Hillman reactions of aldimines 2 with several activated conjugated dienes were found to proceed smoothly in DMF in the presence of 3-hydroxyquinuclidine (HQD). Imines 2 reacted with 1-(p-toluenesulfonyl)-1,3-butadiene (3), methyl 2,4-pentadienoate (6), hexa-3,5-dien-2-one (7),...
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PMID: 17381156
PDF is available here.
PDF is available here.
Abstract
Diene substituent effects on the regiochemical and stereochemical outcomes of uncatalyzed Diels-Alder reactions of N-alkoxycarbonyl-1,2-dihydropyridines with both styrene and methyl vinyl ketone (MVK) were studied. Alkyl substitution on the diene in all cases examined resulted in a kinetic preferenc...
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PMID: 17394357
PDF is available here.
PDF is available here.
Abstract
Delta9,10-Octal-1-one (3,4,5,6,7,8-hexahydro-1(2H)-naphthalenone, 1) can be deprotonated at either of its two gamma positions to form the isomeric exocyclic (1-exo) and endocyclic (1-endo) dienolates. The rate of deuterium exchange for the gammaexo protons of 1 (1.6(+/-0.1)x10(-4) M-1 s-1) is 12-fol...
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PMID: 17388635
PDF is available here.
PDF is available here.
Abstract
A highly efficient method for the synthesis of 1-azabicyclo[x.y.0]alkane amino acid derivatives and their congeners by means of extremely regioselective cyclohydrocarbonylation (CHC) is described. The CHC reactions are catalyzed by Rh-BIPHEPHOS complex under mild conditions. These CHC reaction proces...
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PMID: 17346029
PDF is available here.
PDF is available here.
Abstract
A new Pd-catalyzed one-pot multicomponent coupling reaction for the construction of benzene ring fused with carbocycle or heterocycle under a Cu-free condition is described.
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PMID: 17325797
PDF is available here.
PDF is available here.
Abstract
Two principal subunits of the marine algal toxin (-)-gymnodimine were synthesized. A trisubstituted tetrahydrofuran representing C10-C18 of the toxin was prepared via a highly stereoselective iodine-mediated cyclization of an acyclic alkene bearing a bis-2,6-dichlorobenzyl (DCB) ether. The formation...
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PMID: 17263581
PDF is available here.
PDF is available here.
Abstract
We report herein a detailed investigation into the reaction mechanism of the oxy-Cope/Claisen/ene reaction. A series of chiral substrates was prepared, subjected to the tandem sequence, and the enantiomeric excess of the final products was evaluated. The observed conservation of enantiomeric excess...
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PMID: 17256936
PDF is available here.
PDF is available here.