- Hydride reduction of a lactate ester: Optimisation and scale-up
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The two-step synthesis of (2S)-2-(tetrahydropyran-2-yloxy)-propane-1-ol was selected for fine chemical scale-up. The first step, an acid-catalyzed protection of ethyl (S)(-)-lactate with 3,4-dihydro-2H-pyran, could be performed without solvent. The reaction enthalpy was determined to be -48 kJ/mol ethyl (S)-(-)-lactate, ensuring safe scale-up. The crude reaction mixture was used in the second step, the hydride reduction. For the reduction of the protected ester a clear solution of 1 M LiAlH4 in THF was used. The reaction enthalpy was determined to be -313 kJ/mol ethyl (2S)-2-(tetrahydropyran-2-yloxy)propionate, and the work-up was optimised with experimental design techniques. Combination of all experimental and theoretical results resulted in a master recipe for a 10-dm3 scale synthesis of (2S)-2-(tetrahydropyran-2-yloxy)propane-1-ol.
- Donners,Hersmis,Custers,Meuldijk,Vekemans,Hulshof
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Read Online
- Transformation of esters into allyl halides via substituted cyclopropanols. Application in the synthesis of (2S,3R,7R/S)-3,7-dimethyltridec-2-yl acetate and propionate, sex attractants of pine sawfly Diprion pini
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A convenient new approach to the synthesis of the acetate and the propionate of (2S,3R,7R/S)-3,7-dimethyltridecan-2-ol, sex attractants of Diprion pini L., using the cyclopropanation of the ethoxycarbonyl group in O-THP protected ethyl (S)-lactate with ethylmagnesium bromide in the presence of titanium(IV) isopropoxide followed by C-2-C-3 cyclopropane ring opening as the key steps has been performed.
- Bekish, Andrey V.,Prokhorevich, Konstantin N.,Kulinkovich, Oleg G.
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- Design and synthesis of paracaseolide a analogues as selective protein tyrosine phosphatase 1B inhibitors
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A series of structurally related analogues of the natural product paracaseolide A were synthesized and identified as potent PTP1B inhibitors. Among these analogues, compound 10 in particular showed improved PTP1B enzyme inhibitory activity, high selectivity for PTP1B over TC-PTP, and improved cellular effects. the Partner Organisations 2014.
- Yin, Jian-Peng,Tang, Chun-Lan,Gao, Li-Xin,Ma, Wei-Ping,Li, Jing-Ya,Li, Ying,Li, Jia,Nan, Fa-Jun
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Read Online
- Total Synthesis of (+)-Fusarisetin A Driven by a One-Pot Four-Reaction Process
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A concise, asymmetric total synthesis of (+)-fusarisetin A, a hybrid natural product, has been achieved. A one-pot four-reaction process efficiently delivered the tetracycle 2 which served as a key intermediate for the synthesis of the title natural product and its analogues through amino acid incorporation.
- Liu, Chenguang,Zeng, Zhixiong,Chen, Renzhi,Jiang, Xunjin,Wang, Yinglu,Zhang, Yandong
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supporting information
p. 624 - 627
(2016/02/18)
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- SMALL MOLECULE COMPOUNDS SELECTIVE AGAINST GRAM-NEGATIVE BACTERIAL INFECTIONS
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The described invention provides fully synthetic, biologically active mangrolide A. It describes schemes to chemically synthesize mangrolide A, intermediates and analogs of mangrolide A, and their antibacterial activity.
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Paragraph 0330; 0333; 0334; 0405
(2016/01/30)
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- Total synthesis of lacosamide
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Total synthesis of anticonvulsant amino acid, lacosamide, is reported. The key step is stereospecific allyl cyanate-to-isocyanate rearrangement, which proceeds with chirality transfer. The enantiopure starting material for the rearrangement step was accessed from ethyl l-lactate.
- Stecko, Sebastian
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p. 6342 - 6346
(2014/07/21)
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- Folding of a donor-containing ionene by intercalation with an acceptor
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Cationic ionenes that bear electron-rich 1,5-dialkoxynaphthalene (DAN) units within the alkylene segment were allowed to interact with different types of electron-deficient, acceptor-containing molecules in an effort to realize intercalation-induced folding of the ionenes; the collapse of the chains was expected to occur in such a way that the donor and acceptor units become arranged in an alternating fashion. Several acceptor-bearing molecules were prepared by the derivatization of pyromellitic dianhydride and naphthalene tetracarboxylic dianhydride with two different oligoethylene glycol monomethyl ether monoamines. This yielded acceptor molecules with different water solubility and allowed the examination of solvophobic effects in the folding process. UV/Vis spectroscopic studies were carried out by using a 1:1 mixture of the DAN-ionenes and different acceptor molecules in water/DMSO solvent mixtures. The intensity of the charge-transfer (CT) band was seen to increase with the water content in the solvent mixture, thereby suggesting that the intercalation is indeed aided by solvophobic effects. The naphthalene diimide (NDI) bearing acceptor molecules consistently formed significantly stronger CT complexes when compared to the pyromellitic diimide (PDI) bearing acceptor molecules, which is a reflection of the stronger π-stacking tendency of the former. AFM studies of drop-cast films of different ionene-acceptor combinations revealed that compact folded structures are formed most effectively under conditions in which the strongest CT complex is formed. Know when to fold 'em: When coerced to collapse in a polar solvent in the presence of an electron-deficient amphiphilic folding agent, suitably modified ionenes with a symmetrically positioned electron-rich 1,5-dialkoxylnaphthalene (DAN) unit appear to form an accordion-type folded structure wherein the units are arranged in an alternating fashion (see picture). D=Donor; A=Acceptor. Copyright
- De, Swati,Ramakrishnan
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supporting information; experimental part
p. 149 - 156
(2011/10/08)
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- Identification of absolute helical structures of aromatic multilayered oligo(m-phenylurea)s in solution
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(Chemical Equation Presented) The oligomeric aromatic ureas bearing N,N′-dimethylated urea bonds such as 3 have aromatic multi-layered structure, based on the (cis,cis)-urea structure, and also have dynamic helical structure (all-R or all-S axis chirality) when the benzene rings are connected at the meta positions. The absolute helical structure of oligo(m-phenylurea)s were identified by the empirical and theoretical studies on the CD and vibrational CD (VCD) spectra. Thus, each enantiomer of the oligo(m-phenylurea)s 4 bearing a chiral N-2-(methoxyethoxyethoxy)propyl group were synthesized. Intense dispersion-type CD spectra of 4 were observed, which indicated the induction of handedness in the helical structure. In the VCD spectra of 4 in the film state, the signals due to the carbonyl and aromatic ring vibrations were seen with negative and positive values for compounds 4a and 4b, respectively. The calculations of both CD and VCD spectra of oligo(m-phenylurea)s 3 without any chiral N-substituent gave the same assignment about the axis chirality of 4. Thus, the absolute configurations of 4a and 4b are all-R and all-S structures, respectively. 2009 American Chemical Society.
- Kudo, Mayumi,Hanashima, Takayuki,Muranaka, Atsuya,Sato, Hisako,Uchiyama, Masanobu,Azumaya, Isao,Hirano, Tomoya,Kagechika, Hiroyuki,Tanatani, Aya
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experimental part
p. 8154 - 8163
(2010/02/28)
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- Synthesis of the active form of loxoprofen by using allylic substitutions in two steps
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High regioselectivity for allylic substitution of the cyclopentenyl picolinate 5 with benzylcopper reagent was attained with ZnBr2, and the finding was applied to the p-BrC6H4CH2 reagent. The cyclopentene moiety in the product was reduced to the cyclopentane, and the p-BrC6H4 was converted to the "Cu"C6H4 for the second allylic substitution with picolinate 8 to furnish the title compound after oxidative cleavage of the resulting olefin moiety.
- Hyodo, Tomonori,Kiyotsuka, Yohei,Kobayashi, Yuichi
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supporting information; experimental part
p. 1103 - 1106
(2009/07/25)
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- A male-produced aggregation pheromone blend consisting of alkanediols, terpenoids, and an aromatic alcohol from the cerambycid beetle Megacyllene caryae
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Bioassays conducted with a Y-tube olfactometer provided evidence that both sexes of the cerambycid beetle Megacyllene caryae (Gahan) were attracted to odor produced by males. Odor collected from male M. caryae contained eight male-specific compounds: a 10:1 blend of (2S,3R)- and (2R,3S)-2,3-hexanediols (representing 3.2±1.3% of the total male-specific compounds), (S)-(-)-limonene (3.1±1.7%), 2-phenylethanol (8.0±2.4%), (-)-α-terpineol (10.0±2.8%), nerol (2.1±1.5%), neral (63.3±7.3%), and geranial (8.8±2.4%). Initial field bioassays determined that none of these compounds was attractive as a single component. Further field trials that used a subtractive bioassay strategy determined that both sexes were attracted to the complete blend of synthetic components, but the elimination of any one component resulted in a decline in trap captures. Blends that were missing (2S,3R)-2,3-hexanediol, (2R,3S)-2,3-hexanediol, or citral (a 1:1 mixture of neral and geranial) attracted no more beetles than did controls. A pheromone blend of this complexity, composed of alkanediols, terpenoids, and aromatic alcohols, is unprecedented for cerambycid species.
- Lacey, Emerson S.,Moreira, Jardel A.,Millar, Jocelyn G.,Hanks, Lawrence M.
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p. 408 - 417
(2008/09/18)
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- Self-assembly of photochromic diarylethenes with amphiphilic side chains: Reversible thermal and photochemical control
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(Graph Presented) Diarylethene derivatives with hexaethylene glycol side chains were synthesized and their self-assembling and photochromic reactivity were investigated. The diarylethenes showed photochromism in organic solvents and even in water. The aqueous solution of the compounds turned turbid quickly upon heating. The clouding behavior was investigated using 1H NMR spectroscopy, dynamic light scattering, and absorption spectroscopy. It was revealed that, in the aqueous solution, the compounds self-assembled into aggregates, and the aggregates were loosened by raising the temperature. The cloud-point temperature of the closed-ring isomer was 5-7°C lower than that of the open-ring isomer. When asymmetric methyl groups were introduced in the amphiphilic side chains, induced circular dichroism (ICD) was observed upon irradiation with UV light in water. This ICD was explained by the difference in the self-assembling behavior between the open- and the closed-ring isomers. It was suggested that the closed-ring isomers assembled into a chiral nanostructure.
- Hirose, Takashi,Matsuda, Kenji,Irie, Masahiro
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p. 7499 - 7508
(2007/10/03)
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- Analogs of 4-hydroxyisoleucine and uses thereof
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The invention relates to analogs of 4-hydroxyisoleucine, and to lactones, pharmaceutically acceptable salts, and prodrugs thereof, to processes for their preparation, and to pharmaceutical compositions comprising the same. The analogs of the invention stimulate both glucose uptake and insulin secretion, and may thus be useful for the prevention and treatment of disorders of carbohydrate or lipid metabolism, including diabetes mellitus (type 1 and type 2 diabetes), pre-diabetes, and Metabolic Syndrome.
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Page/Page column 52
(2008/06/13)
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- Compounds and compositions for use in the prevention and treatment of obesity and related syndromes
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The invention relates to 4-hydroxyisoleucine, isomers, analogs, lactones, salts, and prodrugs thereof, to processes for their preparation, and to pharmaceutical compositions comprising the same. More particularly, the invention relates to the use of those compounds in the prevention and treatment of obesity and related syndromes.
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Page/Page column 65
(2010/11/24)
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- Solvent-free carbon-oxygen bond formation catalysed by CeCl 3·7H2O/NaI: Tetrahydropyranylation of hydroxy groups
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An efficient and highly chemoselective method fo the protection of free hydroxy compounds with 3,4-dihydro-2H-pyran is reported. Since the deprotection of THP-ethers occurs very readily at room temperature, the successful use of this type of protecting group depends only upon how readily it can be introduced. For this we have examined the tetrahydropyranylation of alcohols and phenols catalysed by the CeCl3·7H2O/NaI system surface under solvent-free conditions. The reaction presents the advantage of being performable under extremely mild conditions by use of catalytic amounts of an interesting Lewis acidic system consisting of the CeCl3· 7H2O/NaI catalyst combination, which can be easily separated from the reaction mixture. The advantages of this procedure, which utilizes cheap and "lfriendly" reagents, over the previously reported ones are discussed. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Bartoli, Giuseppe,Giovannini, Riccardo,Giuliani, Arianna,Marcantoni, Enrico,Massaccesi, Massimo,Melchiorre, Paolo,Paoletti, Melissa,Sambri, Letizia
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p. 1476 - 1482
(2007/10/03)
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- Hierarchical growth of chiral self-assembled structures in protic media
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The location of nine chiral penta(ethylene oxide) side chains at the periphery of a C3-symmetrical hydrogen-bonded extended core gives rise to a thermotropic discotic liquid crystalline material that shows lyotropic phases in polar, protic media. The molecular stacks self-assemble in a reversible and hierarchical fashion, and specific and subtle solvent-molecule interactions together with the created hydrophobic microenvironment account for an unprecedented stabilization of a preferred handedness of the helical stacks by cooperative intermolecular interactions. The presence of either chirality or achirality at the supramolecular level in the stacks can be tuned by temperature and solvent as judged from circular dichroism spectroscopy. A hierarchical growth of the self-assembly is revealed using a variety of spectroscopic techniques and differential scanning calorimetry.
- Brunsveld,Zhang,Glasbeek,Vekemans,Meijer
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p. 6175 - 6182
(2007/10/03)
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- Stereoselective synthesis of highly functionalized cyclopropanes. Application to the asymmetric synthesis of (1S,2S)-2,3-methanoamino acids
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One-pot palladium(0)-catalyzed alkylation and S(N') cyclization of 1,4- dichlorobut-2-ene 1 by the anion of α-substituted carbonitriles 2a-d can provide highly functionalized cyclopropanes (E)-4a-d, diastereoselectivity, (de 88-100%). Several attempts to achieve the asymmetric synthesis of the 1- amino-2-ethenylcyclopropanecarbonitrile (E)-9, by means of this new procedure, i.e., using chiral palladium ligands, chiral aminoacetonitriles (- )- and (+)-12 (from 1-hydroxypinanone) or chiral allyl chlorides (4S)-20b-d and (4R)-20e (from (2S) ethyl lactate) have pointed up the reversibility of the palladium-catalyzed cyclization step, responsible for the low enantioselectivity observed (ee ≤ 32%) and for the formation of byproducts, i.e., azepine derivatives 8a,b arising from subsequent aza Cope ring expansion. Molecular mechanics calculations using a modified MM2 type force field adapted to the π-allyl palladium complexes have explained these results. However, When performed under the Mitsunobu reaction conditions (DEAD, PMe3), therefore, in the absence of palladium catalyst, the S(N'), cyclization occurred also diastereoselectively (de > 88%) and provided the enantiomerically enriched 1-amino-2-propenylcyclopropanecarbonitrile (E)-22 (ee > 83%) suitable precursor of (1S,2S)-2,3-methanoamino acids.
- Dorizon, Philippe,Su, Guifa,Ludvig, Gitte,Nikitina, Lilyia,Paugam, Renee,Ollivier, Jean,Salauen, Jacques
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p. 4712 - 4724
(2007/10/03)
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- Asymmetric reduction of α-keto esters and α-diketones with a bakers' yeast keto ester reductase
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Optically pure α-hydroxy esters and α-hydroxy ketones have been synthesized by the reduction of the corresponding ketones with a keto ester reductase isolated from bakers' yeast (YKER-I). The reduction of α-keto esters affords the corresponding (S)- or (R)-hydroxy esters selectively, where the stereochemical course depends on the chain length of the alkyl substituent on the carbonyl group. An α-keto short alkanoic ester affords the corresponding (S)-hydroxy ester, whereas a long alkanoate yields the corresponding (R)-hydroxy ester. The reduction of α-diketones affords the corresponding (S)-2-hydroxy ketones regio- and stereoselectively.
- Kawai, Yasushi,Hida, Kouichi,Tsujimoto, Munekazu,Kondo, Shin-Ichi,Kitano, Kazutada,Nakamura, Kaoru,Ohno, Atsuyoshi
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- Temperature dependent inversion of enantiomer selectivity in the complexation of optically active azophenolic crown ethers containing alkyl substituents as chiral barriers with chiral amines
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Azophenolic crown ethers (S,S)-1, (R,R)-2 and (S,S)-3 have been prepared in enantiomerically pure forms by using (S)-1-(1′-adamantyl)ethane-1,2-diol, (R)-3,3-dimethylbutane-1,2-diol and (S)-propane-1,2-diol, respectively, as chiral subunits, and the assoc
- Hirose, Keiji,Fuji, Junichi,Kamada, Kimiko,Tobe, Yoshito,Naemura, Koichiro
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p. 1649 - 1657
(2007/10/03)
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- Preparation of optically active azophenolic crown ethers containing 1-phenylethane-1,2-diol and 2,4-dimethyl-3-oxapentane-1,5-diol as a chiral subunit: Temperature-dependent enantiomer selectivity in the complexation with chiral amines
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With (2S,4S)-2,4-dimethyl-3-oxapentane-1,5-diol and (S)- or (R)-1-phenylethane-1,2-diol as chiral subunits, optically active azophenolic crown ethers (S,S,S,S)-1, (R,S,S,R)-2, (S,S,S,S)-3 and (R,S,S,R)-4 possessing two phenyl and two methyl substituents together with the p-(2,4-dinitrophenylazo)phenol moiety have been prepared in enantiomerically pure forms. Temperature-dependent enantiomer selectivity in the complexation of these crown ethers with chiral amines has been studied by the UV-visible spectroscopic method in chloroform and from the observed association constants, thermodynamic parameters for the complexation have been calculated.
- Ogasahara, Kazuko,Hirose, Keiji,Tobe, Yoshito,Naemura, Koichiro
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p. 3227 - 3236
(2007/10/03)
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- SYNTHESIS OF ENANTIOMERIC N-(2-PHOSPHONOMETHOXYPROPYL) DERIVATIVES OF PURINE AND PYRIMIDINE BASES. I. THE STEPWISE APPROACH
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The (R)- and (S)-N-(2-phosphonomethoxypropyl) derivatives of purine and pyrimidine bases (PMP derivatives) exhibit very high activity against retroviruses.This paper describes the synthesis of enantiomeric 9-(2-phosphonomethoxypropyl)adenines (I and XXVII), 9-(2-phosphonomethoxypropyl)-2,6-diaminopurines (II and XXXI), 9-(2-phosphonomethoxypropyl)guanines (III and XXIX) and 1-(R)-(2-phosphonomethoxypropyl)cytosine (XIX) by alkylation of N-protected N-(2-hydroxypropyl) derivatives of the corresponding bases with bis(2-propyl) p-toluenesulfonyloxymethylphosphonate (X), followed by stepwise N- and O-deprotection of the intermediates.The key intermediates, N-(2-hydropxypropyl) derivatives IX and XXV, were obtained by alkylation of the appropriate heterocyclic base with (R)- or (S)-2-(2-tetrahydropyranyloxy)propyl p-toluenesulfonate (VII or XXIII) ans acid hydrolysis of the resulting N- derivatives VIII and XXII.The chiral synthons were prepared by tosylation of (R)- or (S)-2-(2-tetrahydropyranyloxy)propanol (VI or XXI) available by reduction of enantiomeric alkyl 2-O-tetrahydropyranyllactates V and XXI with sodium bis(2-methoxyethyoxy)aluminum hydride.This approach was used for the synthsis of cytosine, adenine and 2,6-diaminopurine derivatives, while compounds derived from guanine were prepared by hydrolysis of 2-amino-6-chloropurine intermediates.Cytosine derivative IXe was also synthesized by alkylation of 4-methoxy-2-pyrimidone followed by ammonolysis of the intermediate IXf.
- Holy, Antonin,Masojidkova, Milena
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p. 1196 - 1212
(2007/10/02)
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- Preparation and Enantiomer Recognition of Chiral Azophenolic Crown Ethers Having three Chiral Barriers on each of the Homotopic Faces
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Homochiral azophenolic crown ethers 1 and 2 having three chiral barriers, that is, the phenyl group, the methyl group, and the cyclohexane moiety on each of the homotropic faces have been prepared.The enantiomer recognition toward chiral 2-aminoethanol derivatives has been examined.
- Naemura, Koichiro,Asada, Masaki,Hirose, Keiji,Tobe, Yoshito
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p. 1873 - 1876
(2007/10/03)
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- Stereochemistry of an Allyl Cyanate-to-isocyanate Rearrangement
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The stereochemistry of an allyl cyanate-to-isocyanate rearrangement has been investigated by employing a chiral allyl carbamate.The rearrangement has been found to be stereospecific and the chirality of an allyl cyanate is transformed into that of an ally
- Ichikawa, Yoshiyasu,Tsuboi, Katsunori,Isobe, Minoru
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p. 2791 - 2796
(2007/10/02)
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- (S)-(-)-ethyl lactate as a convenient precursor for synthesis of chiral liquid crystals
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A strategy is presented for synthesis of optically active precursors derived from (S)-(-)-ethyl lactate for use in synthesis of chiral liquid crystals.
- Merlo,Gallardo
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p. 2159 - 2169
(2007/10/02)
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- New Symmetrical Chiral Dibenzyl- and Diphenyl-Substituted Diamido-, Dithionoamido-, Diaza-, and Azapyridino-18-crown-6 Ligands
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Eleven new chiral macrocycles (1-11, see Figure 1) of the pyridino-18-crown-6 type have been prepared.Nine diazapyridino-crown ligands contain two amide (1, R = benzyl; 4, R = phenyl), two N-methylamide (7, R = phenyl), two thionoamide (2, R = benzyl; 5,
- Huszthy, Peter,Oue, Masatoshi,Bradshaw, Jerald S.,Zhu, Cheng Y.,Wang, Tingmin,et al.
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p. 5383 - 5394
(2007/10/02)
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- EFFECTIVE SYNTHESIS OF ENANTIOMERIC 2-PENTANOLS AND CHIRAL DOMINICALURES BASED ON THEM
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The (S) and (R) enantiomers of sec-amyl-2-methyl-(2E)-pentenoate and 2,4-dimethyl-(2E)-pentenoate (dominicalure 1 and dominicalure 2 respectively), which are contained in the aggregation pheromone of the lesser grain borer Rhizopertha dominica, were synthesized by the acylation of (S)- and (R)-2-pentanols. (2S)-Pentanol was obtained in five stages with an overall yield of > 50percent from (S)-ethyl lactate with cross-coupling of the p-toluenesulfonate of (2S)-(2-tetrahydropyranyloxy)-1-propanol with lithium diethylcuprate at the key stage.Zinc chloride can be used as an effective catalyst for the removal of the tetrahydropyranyl protection under mild conditions. (2R)-Pentanol was prepared by inversion of the configuration of its (S) enantiomer by the Mitsunobu method.
- Cheskis, B. A.,Shpiro, N. A.,Moiseenkov, A. M.
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p. 1613 - 1616
(2007/10/02)
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- An (S)-(+)-Lactic Acid Route to (2S,6R,8S)-2,8-Dimethyl-1,7-dioxaspiroundecane and (2S,6R,8S)-2-Ethyl-8-methyl-1,7-dioxaspiroundecane and Demonstration of their Presence in the Rectal Glandular Secretion of Bactrocera nigrotibialis (Perkin)
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The chiral iodide resulting from reduction and iodination of the tetrahydropyran-2-yl ether of ethyl (S)-(+)-lactate has been engaged in a free-radical addition to acrylonitrile.The resulting protected hydroxy nitrile, on reaction with pent-4-enylmagnesium bromide afforded (S)-2-tetrahydropyran-2-yloxyundec-10-en-6-one.Oxymercuration of this hydroxy enone, under reversible conditions, employing aqueous acid-tetrahydrofuran, effected simultaneous deprotection and cyclisation, and in situ biphasic demercuration with sodium borohydride provided essentially stereochemically pure (2S,6R,8S)-2,8-dimethyl-1,7-dioxaspiroundecane .Epoxidation of the protected hydroxy enone, followed by dimethylcuprate ring-opening and cyclisation, provided a mixture of the (E,E) and the two possible (E,Z)-diastereomers of 2-ethyl-8-methyl-1,7-dioxaspiroundecane with the former being the (2S,6R,8S) stereoisomer.Separation of the (E,E) from the two (E,Z) isomers was achieved by preparative gas chromatography.GC analysis of these samples and of the rectal glandular secretion of male Bactrocera nigrobialis, using a cyclodextrin-based phase, demonstrated that (2S,6R,8S)-stereoisomers of the 2,8-dimethyl-and 2-ethyl-8-methyl-1,7-dioxaspiroundecanes were the natural products, with no detectable level of the antipodes.
- Perkins, Michael V.,Kitching, William,Koenig, Wilfried A.,Drew, Richard A. I.
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p. 2501 - 2506
(2007/10/02)
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- Synthesis and Mesomorphic Properties of 4-Substituted Phenyl and Phenylthio-4'--Benzoates
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A variety of esters and thioesters of the type were prepared by esterification of the acid with the phenols and thiols using the carbodiimide method.These compounds were of interest as possible ferroelectric liquid crystals.The required acid was
- Neubert, M. E.,Sabol-Keast, S.
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- Synthesis of (-)-Biopterin Using (S)-Ethyl Lactate as a Starting Material
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(-)-Biopterin was synthesized from (1S,2S)-1-(1,3-dithian-2-yl)propane-1,2-diol 5 (=C), which was derived from commercially available (S)-ethyl lactate.Diol 5 (=C) was converted to 15 through a six-step sequence.Ketone 15 was submitted to condensation with 3,5,6-triaminopyrimidinol (TAP, 2), and followed by oxidation to afford isopropylidenebiopterin (16).Finally, 16 was deprotected to give (-)-biopterin (1).
- Kikuchi, Haruhiko,Mori, Kenji
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p. 2095 - 2100
(2007/10/02)
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- THE STEREOSELECTIVE SYNTHESIS OF DISUBSTITUTED E,Z-DIENE ESTER
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The new method for the stereoselective synthesis of disubstituted diene ester was successfully applied to a highly stereoselective synthesis of E,Z-diene ester (1).
- Okay, Guerol
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p. 2125 - 2132
(2007/10/02)
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- The Synthesis of Ferroelectric Liquid Crystal Materials
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Six compounds with the general structure R-PH-PH-COO-PH-O-CH2-CH(CH3)-OP' were synthetized, where R is a n-alkyl or n-alkoxy group of seven to twelve carbon atoms, R' is an alkyl group of three to five carbon atoms, and PH is a phenyl ring.The synthesis p
- Liang, Jason C.,Kumar, Satyendra
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p. 115 - 126
(2007/10/02)
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- Synthesis and Electro-Optical Properties of Some Ferroelectric Liquid Crystals Derived from Lactic Acid
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We have synthesized two series of liquid crystals, viz. 4'-(ω-(2-ethoxy)propoxy)alkoxyphenyl 4-alkoxybenzoate, 2, (abbreviated Cm-Cn-OEt*) and 4'-(ω-(2-chloro)propoxy)alkoxyphenyl 4-alkoxybenzoate, 3, (abbreviated Cm-Cn-Cl*).Compound
- Otterholm, Bengt,Alstermark, Christer,Flatischler, Kurt,Dahlgren, Anders,Lagerwall, Sven T.,Skarp, K.
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p. 189 - 216
(2007/10/02)
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- DIASTEREOSELECTIVE AND ENANTIOSPECIFIC SYNTHESIS OF KEY INTERMEDIATES TO L-SUGARS FROM ETHYL L-LACTATE
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"Building blocks" 3 , which are potential intermediates for the synthesis of L-pentoses or L-hexoses, have been prepared stereoselectively in both diastereomeric forms starting from the ethyl L-lactate.
- Guanti, Giuseppe,Banfi, Luca,Narisano, Enrica
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p. 681 - 688
(2007/10/02)
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- SYNTHETIC STUDIES TOWARD VERRUCOSIDIN: DETERMINATION OF THE ABSOLUTE CONFIGURATION
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The tetrahydrofuran portion 3 of verrucosidin 1, a potent neurotoxin, is synthesized in an enantiomerically pure form via the stereoselective osmylation of the chiral hydroxy diene ester 5 as a key step.
- Cha, Jin K.,Cooke, R. J.
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p. 5473 - 5476
(2007/10/02)
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- Stereochemical Evidence for Pseudorotation in the Reaction of a Phosphoric Monoester
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The phosphoro group of 2-phosphoropropane-1,2-diol migrates to the 1-position on heating in aqueous acid.This migration occurs by two routes.The direct route is belived to proceed via a pentacoordinate intermediate that must, by Westheimer's rules, pseudo
- Buchwald, Stephen L.,Pliura, Diana H.,Knowles, Jeremy R.
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p. 4916 - 4922
(2007/10/02)
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- Stereochemistry of Aliphatic Carbocations, 13. Protonated Cyclopropanes as Intermediates in 1,2-Alkyl Shifts
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The nitrous acid deamination of 2-ethyl-1-methylbutylamine (10), 1,2-diethylbutylamine (35), and 2-ethyl-1-methylpentylamine (43) has been studied with respect to 1,2-alkyl shifts.Optically active and deuterated amines were employed whenever possible.The structure, configuration, and deuterium distribution of various products (e. g. 16 from 10, 40 and 48 from 35, 56 from 43) are most reasonably explained in terms of alkyl-bridged intermediates (corner-protonated cyclopropanes) which isomerize via proton shifts from corner to corner.The alternative interconversion of open ions via 1,3-H shifts is incompatible with our experimental results.
- Kirmse, Wolfgang,Loosen, Karin,Prolingheuer, Ernst-Christoph
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p. 129 - 141
(2007/10/02)
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