- Simple Plug-In Synthetic Step for the Synthesis of (?)-Camphor from Renewable Starting Materials
-
Racemic camphor and isoborneol are readily available as industrial side products, whereas (1R)-camphor is available from natural sources. Optically pure (1S)-camphor, however, is much more difficult to obtain. The synthesis of racemic camphor from α-pinene proceeds via an intermediary racemic isobornyl ester, which is then hydrolyzed and oxidized to give camphor. We reasoned that enantioselective hydrolysis of isobornyl esters would give facile access to optically pure isoborneol and camphor isomers, respectively. While screening of a set of commercial lipases and esterases in the kinetic resolution of racemic monoterpenols did not lead to the identification of any enantioselective enzymes, the cephalosporin Esterase B from Burkholderia gladioli (EstB) and Esterase C (EstC) from Rhodococcus rhodochrous showed outstanding enantioselectivity (E>100) towards the butyryl esters of isoborneol, borneol and fenchol. The enantioselectivity was higher with increasing chain length of the acyl moiety of the substrate. The kinetic resolution of isobornyl butyrate can be easily integrated into the production of camphor from α-pinene and thus allows the facile synthesis of optically pure monoterpenols from a renewable side-product.
- Calderini, Elia,Drienovská, Ivana,Myrtollari, Kamela,Pressnig, Michaela,Sieber, Volker,Schwab, Helmut,Hofer, Michael,Kourist, Robert
-
p. 2951 - 2956
(2021/06/18)
-
- Enantioselective Construction of Modular and Asymmetric Baskets
-
The precise positioning of functional groups about the inner space of abiotic hosts is a challenging task and of interest for developing more effective receptors and catalysts akin to those found in nature. To address it, we herein report a synthetic methodology for preparing basket-like cavitands comprised of three different aromatics as side arms with orthogonal esters at the rim for further functionalization. First, enantioenriched A (borochloronorbornene), B (iodobromonorbornene), and C (boronorbornene) building blocks were obtained by stereoselective syntheses. Second, consecutive A-to-B and then AB-to-C Suzuki–Miyaura (SM) couplings were optimized to give enantioenriched ABC cavitand as the principal product. The robust synthetic protocol allowed us to prepare (a) an enantioenriched basket with three benzene sides and each holding either tBu, Et, or Me esters, (b) both enantiomers of a so-called “spiral staircase” basket with benzene, naphthalene, and anthracene groups surrounding the inner space, and (c) a photo-responsive basket bearing one anthracene and two benzene arms.
- Badji?, Jovica D.,Finnegan, Tyler J.,Gunther, Michael J.,Pavlovi?, Radoslav Z.,Wang, Xiuze
-
supporting information
p. 25075 - 25081
(2021/10/25)
-
- Monoterpenoid-based inhibitors of filoviruses targeting the glycoprotein-mediated entry process
-
In this study, we screened a large library of (+)-camphor and (?)-borneol derivatives to assess their filovirus entry inhibition activities using pseudotype systems. Structure-activity relationship studies revealed several compounds exhibiting submicromolar IC50 values. These compounds were evaluated for their effect against natural Ebola virus (EBOV) and Marburg virus. Compound 3b (As-358) exhibited the good antiviral potency (IC50 = 3.7 μM, SI = 118) against Marburg virus, while the hydrochloride salt of this compound 3b·HCl had a strong inhibitory effect against Ebola virus (IC50 = 9.1 μM, SI = 31) and good in vivo safety (LD50 > 1000 mg/kg). The results of molecular docking and in vitro mutagenesis analyses suggest that the synthesized compounds bind to the active binding site of EBOV glycoprotein similar to the known inhibitor toremifene.
- Baev, Dmitriy S.,Maksyutov, Rinat A.,Mordvinova, Ekaterina D.,Pyankov, Oleg V.,Salakhutdinov, Nariman F.,Shcherbakov, Dmitriy N.,Shcherbakova, Nadezhda S.,Sokolova, Anastasiya S.,Tolstikova, Tatyana G.,Yarovaya, Olga I.,Zaykovskaya, Anna V.,Zybkina, Anastasiya V.
-
-
- Molecular cloning and functional characterization of a two highly stereoselective borneol dehydrogenases from Salvia officinalis L
-
Enzymes for selective terpene functionalization are of particular importance for industrial applications. Pure enantiomers of borneol and isoborneol are fragrant constituents of several essential oils and find frequent application in cosmetics and therapy. Racemic borneol can be easily obtained from racemic camphor, which in turn is readily available from industrial side-streams. Enantioselective biocatalysts for the selective conversion of borneol and isoborneol stereoisomers would be therefore highly desirable for their catalytic separation under mild reaction conditions. Although several borneol dehydrogenases from plants and bacteria have been reported, none show sufficient stereoselectivity. Despite Croteau et al. describing sage leaves to specifically oxidize one borneol enantiomer in the late 70s, no specific enzymes have been characterized. We expected that one or several alcohol dehydrogenases encoded in the recently elucidated genome of Salvia officinalis L. would, therefore, be stereoselective. This study thus reports the recombinant expression in E. coli and characterization of two enantiospecific enzymes from the Salvia officinalis L. genome, SoBDH1 and SoBDH2, and their comparison to other known ADHs. Both enzymes produce preferentially (+)-camphor from racemic borneol, but (?)-camphor from racemic isoborneol.
- Drienovská, Ivana,Kolanovi?, Dajana,Chánique, Andrea,Sieber, Volker,Hofer, Michael,Kourist, Robert
-
-
- Synthesis method of levo-borneol
-
The invention relates to a synthetic method of L-borneol. The method comprises: reducing di-n-butyltin dichloride to obtain di-n-butyltin dihydride via lithium aluminium hydride, performing a reactionamong 2-camphanone, palladium bis(triphenylphosphine) dichloride and methanol, adding di-n-butyltin dihydride drop by drop while performing uniform stirring, performing a reaction at the room temperature for 1 h, after the reaction is over, performing pressure-reduction rotary evaporation to remove methanol, and performing separation to obtain L-borneol, which is the target compound.
- -
-
Paragraph 0036; 0039-0041; 0044-0046; 0049-0051; 0054-0055
(2020/09/02)
-
- Alkane-, alkene-, alkyne-γ-lactones and ryanodane diterpenes from aeroponically grown Persea indica roots
-
This work presents the study of the roots of the Macaronesian paleoendemism Persea indica (L.) Spreng. The root biomass of this protected tree species has been produced by soil-less aeroponic culture under controlled environment. This system has important advantages over traditional plant production techniques because it provides opportunities to optimize the yield of metabolite production under well-controlled conditions, thereby facilitating commercial-scale production of bioactive compounds. Thus, for the first time a study of this type has permitted the isolation from the roots of seven undescribed dextrorotatory lactones: the alkane-γ-lactones (+)-majoranolide and (+)-dihydromajorenolide, the alkene-γ-lactones (+)-majorenolide and (+)-majorenolide acetate, and the alkyne-γ-lactones, (+)-majorynolide, (+)-majorynolide acetate and (+)-isomajorynolide. In addition, thirteen known compounds were also isolated including two possible avocadofurane precursors, avocadynone acetate and avocadenone acetate, the monoterpene esters cis- and trans-p-coumarate of (?)-borneol, and the ryanoid diterpenes cinnzeylanone, anhidrocinnzeylanine, cinnzeylanine, cinnzeylanol, epiryanodol, perseanol, cinncassiol E, perseaindicol and secoperseanol. The configuration at C-14 de two ryanodane diterpenes has also been revised in this work. Furthermore, (?)-borneol cis-p-coumarate has showed to be insecticidal to S. littoralis and cytotoxic to insect (Sf9) cells, (+)-majorenolide antifeedant to aphids and cytotoxic to Sf9, cinnceylanol antifeedant and insecticidal to S. littoralis, and (+)-majorynolide (2), insecticidal against S. littoralis, cytotoxic to Sf9 and nematicidal, suggesting a defensive role for these compounds.
- Fraga, Braulio M.,Díaz, Carmen E.,Bola?os, Patricia,Bailén, María,Andrés, María Fe,González-Coloma, Azucena
-
-
- One-Pot Absolute Stereochemical Identification of Alcohols via Guanidinium Sulfate Crystallization
-
A novel technique for the absolute stereochemical determination of alcohols has been developed that uses crystallization of guanidinium salts of organosulfates. The simple one-pot, two-step process leverages facile formation of guandinium organosulfate single crystals for the straightforward determination of the absolute stereochemistry of enantiopure alcohols by means of X-ray crystallography. The strong hydrogen bonding network drives the stability of the crystal lattice and allows for a diverse range of organic alcohol substrates to be analyzed.
- Brummel, Beau R.,Lee, Kinsey G.,McMillen, Colin D.,Kolis, Joseph W.,Whitehead, Daniel C.
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p. 9622 - 9627
(2019/12/02)
-
- Hydrogen Sulfide: A Reagent for pH-Driven Bioinspired 1,2-Diol Mono-deoxygenation and Carbonyl Reduction in Water
-
Hydrogen sulfide (H2S) was evaluated for its peculiar sulfur radical species generated at different pHs and was used under photolytical conditions in aqueous medium for the reduction of 1,2-diols to alcohols. The conversion steps of 1,2-cyclopentanediol to cyclopentanol via cyclopentanone were analyzed, and it was proven that the reaction proceeds via a dual catalytic/radical chain mechanism. This approach was successfully adapted to the reduction of a variety of carbonyl compounds using H2S at pH 9 in water. This work opens up the field of environmental friendly synthetic processes using the pH-driven modulation of reactivity of this simple reagent in water.
- Barata-Vallejo, Sebastián,Ferreri, Carla,Golding, Bernard T.,Chatgilialoglu, Chryssostomos
-
supporting information
p. 4290 - 4294
(2018/07/29)
-
- Preparation method of D-borneol
-
The invention relates to a preparation method of D-borneol. The method comprises the following steps: ensuring that natural camphor is reacted for 1 to 8 hours at 0 to 40 DEG C under the existence ofan organic solvent and a chiral reagent (R)-BINAP-H serving as catalysts, and ensuring that the optimized ratio of the organic solvent to the chiral reagent (R)-BINAP-H to camphor is (10-30ml): (20-50mmol): 18mmol.
- -
-
Paragraph 0032; 0033; 0037; 0042; 0046
(2018/11/22)
-
- An efficient FeCl3-mediated approach for reduction of ketones through N-heterocyclic carbene boranes
-
An efficient FeCl3-mediated approach for reduction of ketones by NHC-BH3 has been developed. A series of ketones were smoothly converted to the corresponding alcohols in good to excellent yields through NHC-BH3 reductive process.
- Wang, Ming-Hui,Chen, Ling-Yan
-
supporting information
p. 732 - 735
(2017/03/31)
-
- Reliable HPLC separation, vibrational circular dichroism spectra, and absolute configurations of isoborneol enantiomers
-
Resolution of chiral compounds has played an important role in the pharmaceutical field, involving detailed studies of pharmacokinetics, physiological, toxicological, and metabolic activities of enantiomers. Herein, a reliable method by high-performance liquid chromatography (HPLC) coupled with an optical rotation detector was developed to separate isoborneol enantiomers. A cellulose tris(3, 5-dimethylphenylcarbamate)-coated chiral stationary phase showed the best separation performance for isoborneol enantiomers in the normal phase among four polysaccharide chiral packings. The effects of alcoholic modifiers and column temperature were studied in detail. Resolution of the isoborneol racemate displayed a downward trend along with an increase in the content of ethanol and column temperature, indicating that less ethanol in the mobile phase and lower temperature were favorable to this process. Moreover, two isoborneol enantiomers were obtained via a semipreparative chiral HPLC technique under optimum conditions, and further characterized by analytical HPLC, and experimental and calculated vibrational circular dichroism (VCD) spectroscopy, respectively. The solution VCD spectrum of the first-eluted component was consistent with the Density Functional Theory (DFT) calculated pattern based on the SSS configuration, indicating that this enantiomer should be (1S, 2S, 4S)-(+)-isoborneol. Briefly, these results have provided reliable information to establish a method for analysis, preparative separation, and absolute configuration of chiral compounds without typical chromophoric groups.
- Gao, Rui-Qi,Fan, Jun,Tan, Qi,Guo, Dong,Chen, Tao,He, Ru-Jian,Li, Dan,Zhang, Hui,Zhang, Wei-Guang
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p. 550 - 557
(2017/08/26)
-
- Vanadium-Catalyzed Oxidative Debenzylation of O-Benzyl Ethers at ppm Level
-
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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- A saponified the ester is continual isoborneol acetate method of preparing isoborneol
-
The invention discloses a method for preparing isoborneol by continuous saponification of isobornyl acetate. The method comprises the following steps: saponifying sodium hydroxide and isobornyl acetate as raw materials, rectifying, layering, washing with water, crystallizing and the like to prepare white isoborneol crystals. The saponification reaction of isobornyl acetate can be continuously carried out in an oscillatory flow reactor, a static mixer or an ultrasonic mixer; a polar solvent is added in the reaction, so that the saponification reaction is heterogeneously carried out, the reaction time can be shortened, the reaction temperature can be reduced, the conversion rate of isobornyl acetate is more than 99%, and the product yield is more than 95%. The method is low in production energy consumption and high in product yield.
- -
-
Paragraph 0043-0051
(2017/01/19)
-
- An unexpected reaction of camphor with sodium metal
-
Reaction of camphor with sodium metal at elevated temperature in refluxing THF or toluene, furnishes an unexpected product. The product has been identified by spectral analysis and its structure confirmed by single crystal X-ray diffraction study. A preliminary mechanistic explanation has been suggested to explain this reaction.
- Khanvilkar, Aditya N.,Gupta, Riddhi,Bedekar, Ashutosh V.
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p. 1327 - 1331
(2016/02/23)
-
- Selective ruthenium-catalyzed epimerization of chiral sec-alcohols
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Extension of secondary alcohol racemization catalyzed by homogeneous half-sandwich ruthenium complexes to the epimerization of natural products containing additional non-functionalized stereo-centers has been investigated. Ruthenium-catalysed epimerization of the sec-alcohols (-)-menthol, (-)-isopulegol, (+)-borneol, (+)-fenchol and cholesterol under mild reaction conditions and low catalyst loadings (2mol%) provides rapid access to their less abundant diastereoisomers (+)-neomenthol, (+)-neoisopulegol, isoborneol, beta-fenchol and epicholesterol in admixture with the parent diastereomers in ratios ranging from 1:4.9 to 1:2.4 (epimer:parent).
- L?ngvik, Otto,Mavrynsky, Denys,Leino, Reko
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p. 255 - 259
(2015/03/14)
-
- Selective ruthenium-catalyzed epimerization of chiral sec-alcohols
-
Extension of secondary alcohol racemization catalyzed by homogeneous half-sandwich ruthenium complexes to the epimerization of natural products containing additional non-functionalized stereo-centers has been investigated. Ruthenium-catalysed epimerization of the sec-alcohols (-)-menthol, (-)-isopulegol, (+)-borneol, (+)-fenchol and cholesterol under mild reaction conditions and low catalyst loadings (2 mol%) provides rapid access to their less abundant diastereoisomers (+)-neomenthol, (+)-neoisopulegol, isoborneol, beta-fenchol and epicholesterol in admixture with the parent diastereomers in ratios ranging from 1:4.9 to 1:2.4 (epimer:parent).
- L?ngvik, Otto,Mavrynsky, Denys,Leino, Reko
-
p. 255 - 259
(2015/02/19)
-
- An unexpected reaction of camphor with sodium metal
-
Reaction of camphor with sodium metal at elevated temperature in refluxing THF or toluene, furnishes an unexpected product. The product has been identified by spectral analysis and its structure confirmed by single crystal X-ray diffraction study. A preliminary mechanistic explanation has been suggested to explain this reaction.
- Khanvilkar, Aditya N.,Gupta, Riddhi,Bedekar, Ashutosh V.
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p. 1327 - 1331
(2015/11/10)
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- Highly enantioselective organocatalytic oxidative kinetic resolution of secondary alcohols using chiral alkoxyamines as precatalysts: Catalyst structure, active species, and substrate scope
-
The development and characterization of enantioselective organocatalytic oxidative kinetic resolution (OKR) of racemic secondary alcohols using chiral alkoxyamines as precatalysts are described. A number of chiral alkoxyamines have been synthesized, and their structure-enantioselectivity correlation study in OKR has led us to identify a promising precatalyst, namely, 7-benzyl-3-n-butyl-4-oxa-5-azahomoadamantane, which affords various chiral aliphatic secondary alcohols (ee up to >99%, krel up to 296). In a mechanistic study, chlorine-containing oxoammonium species were identified as the active species generated in situ from the alkoxyamine precatalyst, and it was revealed that the chlorine atom is crucial for high reactivity and enantioselectivity. The present OKR is the first successful example applicable to various unactivated aliphatic secondary alcohols, including heterocyclic alcohols with high enantioselectivity, the synthetic application of which is demonstrated by the synthesis of a bioactive compound.
- Murakami, Keiichi,Sasano, Yusuke,Tomizawa, Masaki,Shibuya, Masatoshi,Kwon, Eunsang,Iwabuchi, Yoshiharu
-
supporting information
p. 17591 - 17600
(2015/02/19)
-
- Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl groups and deprotection of the obtained trimethylsilanes
-
Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-5 min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR, 1H NMR, 13C NMR and MS studies. All the products were extensively characterized by IR, 1H NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
- Shirini, Farhad,Khaligh, Nader Ghaffari,Akbari-Dadamahaleh, Somayeh
-
-
- Metal-dependent reaction tuning with cyclopentylmetal reagents: Application to the asymmetric synthesis of (+)-α-conhydrine and (S)-2-cyclopentyl-2- phenylgrycolic acid
-
The reaction profile of the cyclopentyl organometallic reagents with the aliphatic ketones can be tuned to reduction or addition by changing the metal atom. Cyclopentylmagnesium bromide (CPMB) reduces aromatic and aliphatic aldehydes and ketones to the corresponding alcohols without any C-C bond formation and shows good diastereoselectivity in the reduction of the substituted cyclic and polycyclic ketones as well as chiral α-oxygenated aliphatic ketones. However, in the presence of 10 mol% of ZnClα 2, the cyclopentylmagnesium halides follow a normal Grignard addition to the ketones to give tertiary alcohols with complete diastereoselectivity. The reductive as well as the addition protocols were used for the asymmetric synthesis of two medicinally important compounds, (+)-α-conhydrine and (S)-2-cyclopentyl-2-phenylglycolic acid.
- Roy, Siddharth,Sharma, Anubha,Mula, Soumyaditya,Chattopadhyay, Subrata
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experimental part
p. 1713 - 1722
(2009/09/07)
-
- Synthesis of a new thiocarbamate by the reaction of benzyl thiocyanate with camphene, catalyzed by heteropoly acids
-
The reaction of benzyl thiocyanate with camphene in the presence of heteropoly acids, 12-phosphotungstic and 12-silicotungstic, at 65 C was studied. S-Benzyl (1,7,7-trimethylnorbornyl)thiocarbamate was prepared in 66% yield.
- Arkhipova,Malkova,Sokolova,Kartashov
-
p. 162 - 163
(2008/01/05)
-
- New active-iron based reducing system for carbonyl compounds and imines. Stereoselective reduction of cyclic ketones
-
The reaction of different carbonyl compounds and imines with a mixture of iron(II) chloride tetrahydrate, an excess of lithium powder, and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 5 mol%) in THF at room temperature, led to the formation of the corresponding alcohols and amines, respectively. The process was also applied to the transformation of α,β-unsaturated carbonyl compounds into the corresponding saturated alcohols. The new reducing system exhibited good to excellent diastereoselectivity toward the reduction of different monocyclic and polycyclic ketones.
- Moglie, Yanina,Alonso, Francisco,Vitale, Cristian,Yus, Miguel,Radivoy, Gabriel
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p. 2812 - 2819
(2007/10/03)
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- The effects of added ammonium chloride in the reductive amination of some carbonyl compounds over Ru and Pd catalysts
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The reductive amination of acetophenone, (+)-camphor, and 5α-cholestan-3-one over Ru and Pd metals as well as their carbon-supported catalysts gave corresponding amines together with alcohols as by-products. However, we found that the corresponding amines are selectively synthesized by the addition of ammonium chloride to the reaction system with depression of the formation of alcohol, as exemplified with acetophenone. Although alcohols are usually not formed over Pd with alicyclic ketones, the alcohols formation was effectively depressed over Ru in the presence of ammonium chloride. The effects of the additive on the stereoselectivity of the formation of amines are also discussed in the cases of (+)-camphor and 5α-cholestan-3-one.
- Ikenaga, Tomoaki,Matsushita, Kumiko,Shinozawa, Junichi,Yada, Satoru,Takagi, Yuzuru
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p. 2105 - 2109
(2007/10/03)
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- Al-isopropoxydiisobutylalane: A study of the effect of solvent on the rate and stereoselectivity of cyclic ketone reduction
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The effect of solvent on the rate and stereoselectivity of cyclic ketone reduction by Al-isopropoxydiisobutylalane (DIBAiOPr) has been investigated. In dichloromethane, DIBAiOPr behaves as a bulky reducing agent, approaching the carbonyl group along an equatorial trajectory to produce the axial alcohol with > 10:1 stereoselectivity. In sharp contrast, reduction in toluene gives the complementary outcome, affording the thermodynamically more stable isomer with > 99:1 stereoselectivity.
- Bahia, Perdip S.,Jones, Matthew A.,Snaith, John S.
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p. 9289 - 9291
(2007/10/03)
-
- Monoterpenoids and their glycosides from the leaf of thyme
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Seven monoterpenoid glycosides, including thymuside A, were isolated from the methanol extract of thyme leaf. From the polar portion of the methanol extract of thyme (leaf of Thymus vulgaris; Labiatae), which has been used as an important stomachic, carminative, a component of prepared cough tea, and a spice, seven monoterpenoid glycosides were isolated together with two known monoterpenoids and three known monoterpenoid glucosides. Structures of the seven monoterpenoid glycosides were determined by spectral analysis.
- Kitajima, Junichi,Ishikawa, Toru,Urabe, Atushi,Satoh, Mitsuru
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p. 3279 - 3287
(2007/10/03)
-
- A convenient route to optically active γ-substituted γ-lactones
-
Sodium borohydride reduction of 4-substituted (-)-menthyl/ (-)-bornyl-4-oxobutanoates followed by simple trituration in acidic medium at low temperature resulted in the formation of optically active γ-substituted γ-lactones.
- Karnik, Anil V.,Patil, Sudhir T.,Patnekar, Subodh S.,Semwal, Abha
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p. 1420 - 1422
(2007/10/03)
-
- Hydrolysis of Alkenyl Esters and Ethers Catalyzed by Metal Complexes
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(Equation presented) Various kinds of transition metals catalyzed the hydrolysis of alkenyl esters and ethers under buffer-free, high concentration conditions compared to usual biocatalysts. Hydrolytic kinetic resolution of cis-2-tert-butylcyclohexyl vinyl ether was achieved by chiral (salen)Co complexes with good selectivity (krel = 10.0).
- Aoyama, Hiroshi,Tokunaga, Makoto,Hiraiwa, Shin-Ichiro,Shirogane, Yuki,Obora, Yasushi,Tsuji, Yasushi
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p. 509 - 512
(2007/10/03)
-
- Method for preparing a benzylic-type ether
-
The invention concerns a method for preparing a benzylic-type ether from an aromatic compound. The inventive method for preparing a benzylic-type ether from an aromatic compound is characterised in that it consists in: in a first step, acylating an aromatic compound by reacting said aromatic compound with an acylating agent, in the presence of an efficient amount of zeolite or a Friedel-Crafts catalyst leading to a ketonic compound; in a second step, reducing the carbonyl group into carbinol leading to a benzylic alcohol; in a third step, etherifying the hydroxyl group, by reacting the benzylic alcohol with another alcohol, in the presence of an efficient amount of zeolite.
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-
- Method of oxidizing an alcohol using a recyclable fluorous sulfoxide
-
A method of oxidizing primary and secondary alcohols to an aldehyde or ketone using a fluorous sulfoxide or a fluorous sulfide is disclosed. The method includes regenerating and recycling the fluorous sulfoxide.
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-
- The reactions of selected terpene alcohols with acetonitrile in the presence of boron trifluoride etherate
-
A series of thirteen terpene alcohols 1-13 of bornane, fenchane and isotricyclene systems was subjected to the reaction with acetonitrile in the presence of BF3·Et2O as a catalyst to give respective acetamides and/or alkenes. The use of boron trifluoride etherate instead of the usually applied protonic donors let us establish beyond any doubt the carbonium ion stage participation. The assumed reaction course was corroborated by cationic Wagner-Meerwein, Namietkin and homoallylic rearrangements observed during studies under investigation. Simultaneously no evidence for the imidate formation was found. Such a mode of the reaction mechanism was alternatively suggested earlier by Sjoeberg [9] for the reaction of sec- and tert-butanol with acetonitrile in the presence of boron trifluoride etherate.
- Welniak
-
p. 1405 - 1411
(2007/10/03)
-
- PERFUME COMPOSITION
-
A perfume composition contains specified ketones, salicylates and alcohols/acetates/propionates. Use of such a perfume composition inhibits development of human body malodour. The combination of specified materials makes it possible to avoid inclusion of individual components with powerful, unacceptable odours. The perfume composition may be used in various products notably in a fabric conditioning product used during the rinsing or tumble drying of fabrics after washing to soften the fabrics.
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-
- Chiral β- and γ-aminoalcohols derived from (+)-camphor and (-)-fenchone as catalysts for the enantioselective addition of diethylzinc to benzaldehyde
-
The addition of Me3SiCN and LiCH2CN to (+)-camphor and (-)-fenchone, respectively, followed by reduction leads to chiral β- and γ-aminoalcohols. The enantioselectivities realized using these aminoalcohols as ligands in the addition of Et2Zn to benzaldehyde were lower than those obtained using the corresponding δ-aminoalcohols.
- Dimitrov, Vladimir,Dobrikov, Georgi,Genov, Miroslav
-
p. 1323 - 1329
(2007/10/03)
-
- Molecular recognition study on supramolecular systems. Part 19. Circular dichroism studies of inclusion complexation of aliphatic alcohols by organoselenium modified β-cyclodextrins
-
Complex stability constants for the stoichiometric 1 : 1 inclusion complexation of various aliphatic alcohols with mono[6-(benzylseleno)-6-deoxy]-β-cyclodextrin (1). mono[6-(phenylseleno)-6-deoxy]-β-cyclodextrin (2), and mono-[6-(o-, m-, or p-tolylseleno)-6-deoxy]-β-cyclodextrin (3-5) have been obtained by spectrophotometric titrations at 25°C in phosphate buffer solution (pH = 7.2). The Cotton effects observed indicate that the aromatic moiety penetrates shallowly into the hydrophobia cavity of cyclodextrin. Therefore, the aromatic moiety can be taken as an induced circular dichroism (ICD) probe to investigate the inclusion phenomena. The results obtained demonstrate that the modified β-cyclodextrin (1) is highly sensitive to the size/shape and conformational rigidity of guest molecules, giving fairly good molecular selectivity up to 114 for adamantan-1-ol/cyclopentanol and relatively high EIZ selectivity up to 2.7 for geraniol/nerol. Interestingly, all of the modified β-cyclodextrins employed displayed relatively good enantioselectivity for (+)-enantiomers of borneol and menthol. The molecular recognition ability and enantioselectivity for aliphatic alcohols of the modified β-cyclodextrins (1-5) are discussed from the viewpoints of the size/shape-fit relationship and the multipoint recognition mechanism.
- Liu, Yu,Li, Bin,Han, Bao-Hang,Wada, Takehiko,Inoue, Yoshihisa
-
p. 563 - 568
(2007/10/03)
-
- Synthesis and applications of a fluorous THP protective group
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A recyclable fluorous labeled THP protecting group has been developed that allows for simple purification of small molecules by liquid-liquid extraction with FC-72/MeCN, and of larger or more polar molecules by solid phase extraction with fluorous reverse phase silica gel. In addition, we report a new glycosylation method which uses the Cp2ZrCl2-AgClO4 reagent system to activate an anomeric sulfoxide.
- Wipf, Peter,Reeves, Jonathan T.
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p. 4649 - 4652
(2007/10/03)
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- Synthesis and applications of fluorous silyl protecting groups with improved acid stability
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Fluorous alkoxysilyl protecting groups have been developed and evaluated for their acid stability. tert-Butylphenyl-1H,1H,2H,2H-heptadecafluorodecyloxysilyl (BPFOS) ethers in particular were found to be surprisingly acid stable and allow simple protection-purification-deprotection schemes by liquid-liquid extraction with FC-72/CH3CN or by solid phase extraction with fluorous reverse phase silica gel.
- Roever, Stephan,Wipf, Peter
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p. 5667 - 5670
(2007/10/03)
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- Preparation of chiral hydroxy carbonyl compounds and diols by ozonolysis of olefinic isoborneol and fenchol derivatives: Characterization of stable ozonides by 1H-, 13C-, and 17O-NMR and electrospray ionization mass spectrometry
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The allylic and homoallylic alcohols 1-8, prepared from (+)-camphor and (-)-fenchone, were ozonized in Et2O at -78°and treated with Et3N or LiAIH4 to give the chiral hydroxy carbonyl compounds 9-16 and the diols 17- 24, respectively (Scheme 1). In the case of the diols 19 and 24, the formation of new chiral centers proceeded with high diastercoselectivity. These diols were prepared highly diastereoselectively also by LiAIH4 reduction of the hydroxy carbonyl compounds 11 and 16a, respectively (Scheme 2). The absolute configuration of the new chiral centers in 19 and 24 was determined by X-ray and NMR methods. The ozonization of compounds 2, 3, 7, and 8 provided the relatively stable hydroxy-substituted 1,2,4-trioxolane derivatives (ozonides) 37-40 (Scheme 5) which were characterized by 1H- and 13C-NMR spectra, ESI-MS, and natural-abundance 17O-NMR spectra.
- Kostova, Kalina,Dimitrov, Vladimir,Simova, Svetlana,Hesse, Manfred
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p. 1385 - 1399
(2007/10/03)
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- Stereocontrolled synthesis of novel enantiomerically pure sulfides and selenides from (+)-camphor and (+)-camphor-10-sulfonyl chloride
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Synthetic approaches to novel enantiomerically pure sulfides and selenides derived from (+)-camphor and (+)-camphor-10-sulfonate esters are described. Lewis acid mediated hemiacetal formation between a camphor- derived ketone and a thiol or selenol, and subsequent in situ reduction using triethylsilane selectively gives the exo-sulfide or -selenide in moderate overall yields. The initial sulfonate ester products can be converted into the corresponding sulfones by subsequent treatment with Grignard or organolithium reagents.
- Procter, David J.,Archer, Nicolas J.,Needham, Robert A.,Bell, David,Marchington, Allan P.,Rayner, Christopher M.
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p. 9611 - 9622
(2007/10/03)
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- Expedient and simple method for regeneration of alcohols from toluenesulfonates using Mg-MeOH
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Efficient conversion of toluenesulfonates to corresponding alcohols with Mg-MeOH is described.
- Sridhar, Madabhushi,Kumar, B. Ashok,Narender
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p. 2847 - 2850
(2007/10/03)
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- Fluorescent Sensors for Molecules Guest-Responsive Monomer and Excimer Fluorescence of 6A,6B-; 6A,6C-; 6A,6D-; and 6A,6E-Bis(2-naphthylsulfonyl)-γ-cyclodextrins
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Flexible hosts, 6A,6B-; 6A,6C-; 6A,6D-; and 6A,6E-bis(2-naphthylsulfonyl)-γ-cyclodextrins (γ-1, γ-2, γ-3, and γ-4, respectively) were used as fluorescent sensors with which a variety of organic compounds were detected by naphthalene excimer and monomer emissions. In a 10 vol% ethylene glycol aqueous solution, γ-1 exhibits almost pure monomer fluorescence while γ-2, γ-3, and γ-4 exhibit both monomer and excimer emissions. The intensities of the emissions changed upon addition of guest species, particularly in the case of γ-2 and γ-3, and the guest-induced intensity variations were used as sensitivity factors of the sensors. When (-)-borneol (5), cyclohexanol (6), cyclododecanol (7), and 1-adamantanecarboxylic acid (8) were added to each host solution, γ-2, γ-3, and γ-4 increased the excimer emission intensity but decreased the monomer one, the absolute intensity variations being 6 5≈8 1. When geraniol (9), nerol (10), and (-)-menthol (11) were added, the hosts decreased intensities in both monomer and excimer emissions for 9 and 10 while their emission variations for 11 were similar to those of 5. For steroids such as cholic acid (12), deoxycholic acid (13), chenodeoxycholic acid (14), and ursodeoxycholic acid (15), γ-4 showed depression in the excimer emission and enhancement in the monomer one while γ-2 and γ-3 showed complicated features in which the excimer emission was enhanced with the order of 15 14 13≈12 but the monomer one was depressed or enhanced depending on the hosts. All these data demonstrate that the hosts can be used as sensors for molecular recognition.
- Hamada, Fumio,Minato, Shingo,Osa, Tetsuo,Ueno, Akihiko
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p. 1339 - 1346
(2007/10/03)
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- Chiral synthesis via organoboranes. 43. Selective reductions. 58. Reagent-controlled diastereoselective reduction of (+)- and (-)-α-chiral ketones with (+)- and (-)-B-chlorodiisopinocampheylborane
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Asymmetric reduction of (+)- and (-)-α-chiral ketones with (+)- and (-)-B-chlorodiisopinocampheylborane provides the product alcohols in very high diastereomeric excess, with the matched pairs providing > 100:1 selectivity and the mismatched pairs showing 4:1-15:1 selectivity. The high selectivity achieved even in the mismatched pairs reveals the power of the reagent to control the stereochemical outcome. The rates of the reaction of the matched pairs are faster than those of the mismatched pairs. In all the cases studied thus far, the (-)-reagent (dIpc2BCl) and (S)-ketone or the (+)-reagent (lIpc2BCl) and (R)-ketone constitute matched pairs and the (-)-reagent and (R)-ketone or the (+)-reagent and (S)-ketone constitute mismatched pairs. A possible mechanism for the reductions is discussed.
- Ramachandran, P. Veeraraghavan,Chen, Guang-Ming,Brown, Herbert C.
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- Chiral Synthesis via Organoboranes. 42. Selective Reductions. 57. Efficient Kinetic Resolution of Representative α-Tertiary Ketones with B-Chlorodiisopinocampheylborane
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Kinetic resolution of racemic α-tertiary ketones with 0.5-0.6 molar equiv of B-chlorodiisopinocampheylborane provides the product alcohols in very high diastereomeric and enantiomeric excess, with the unreacted ketone recovered in very high ee.For example, ethyl 1-methyl-2-oxocyclopentane- and cyclohexanecarboxylates are partially reduced to recover the ketone in 91 to >/=99percent ee and the product alcohols in up to 94percent de, with >90percent ee for the major diastereomer.Bicyclic ketones, such as 1-methyl- and 1-ethylnorcamphor, camphor, and camphenilone, are readily resolved to provide the ketone in 92 to >/=99percent ee, with the product alcohol recovered in high de and ee.Dihydrospirooctane-2,2'(3'H)-furan>-3-one is resolved to provide the ketone in >/=99percent ee and the product alcohol in >/=99percent de.In all the cases studied, the R-isomer of the ketone is recovered when dIpc2BCl is used for kinetic resolution, while lIpc2BCl provides the S-ketone.Optimum conditions for obtaining the product alcohol, or the ketone, or both, in very high yields and ee have been established.
- Ramachandran, P. Veeraraghavan,Chen, Guang-Ming,Brown, Herbert C.
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- Perfume compositions
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A perfume composition contains at least 50% by weight of materials which fall into five categories defined by structure, and molecular weight. Amounts of material within each category fall within specified ranges of percentage of the whole composition. Two categories, ethers and salicylates, must be present. At least two of the remaining three categories, which are alcohols, acetate/propionate esters and methyl aryl ketones, must also be present. The compositions enable good levels of deodorant activity to be achieved along with consumer-acceptable fragrance.
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- Deodorant compositions
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The invention provides a deodorant composition suitable for topical application to the human skin, comprising a composition of fragrance materials which have a Deodorant Value greater than 0.25, as measured by the Deodorant Value Test, and an inorganic deodorant active material, in a cosmetically suitable vehicle.
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- Intramolecular vs. intermolecular induction in the diastereoselective catalytic reduction of enantiomerically pure ketones with borane in the presence of cyclic β-amino alcohols
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Asymmetric reduction of various enantiomerically pure ketones was carried out by using oxazaborolidine catalysts with a variety of achiral and chiral ligands. The efficiency of chiral 1,2-amino alcohols as well as the effect of the stereogenic centers in the substrate on the catalytic asymmetric reduction were studied. It was found that the corresponding secondary alcohols were obtained with extremely high stereoselectivities with the proper choice of chiral ligands although a considerably large double asymmetric induction was observed in some cases.
- Reiners,Wilken,Martens
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p. 3063 - 3070
(2007/10/03)
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- Synthesis of chiral diazanedicarboxylate and diazenedicarboxylate esters: electrophilic amination reactions of achiral ester and amide enolates
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A series of chiral dialkyl (bornyl, isobornyl, menthyl) diazenedicarboxylates 4a-c were prepared by conversion of the corresponding alcohols into chloroformates, condensation with hydrazine, and oxidation of the corresponding dialkyl diazanedicarboxylates 3a-c with N-bromosuccinimide and pyridine (50-90percent yield).Their reaction with achiral enolates of esters and N,N-dimethyl amides at -70 deg C gave α-hydrazino acid derivatives with little or no stereoselectivity.Analogous amination of chiral oxazolidinone (Evans enolate) anions were highly selective, but were controlled exclusively by enolate geometry.
- Harris, Joanna M.,Bolessa, Evon A.,Mendonca, Aubrey J.,Feng, Sheng-Chu,Vederas, John C.
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p. 1945 - 1950
(2007/10/02)
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- Scope and Mechanism of Deprotection of Carboxylic Esters by Bis(tributyltin) Oxide
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Methyl and ethyl esters of aliphatic and aromatic carboxylic acids as well as benzyl carboxylates, thiol esters and double esters such as (pivaloyloxy)methyl carboxylates have been successfully cleaved with bis(tributyltin) oxide to give the free carboxylic acids in good yields.The reaction is carried out in aprotic solvents under essentially neutral conditions and thus this method can serve as an ideal procedure for the cleavages of esters with other functional groups and/or protecting groups acid and/or base sensitive.We demonstrated that the reaction displays a high level of chemoselectivity between methyl and ethyl esters versus tert-butyl esters and γ-lactones.Bis(tributyltin) oxide is also a highly efficient reagent for the cleavage of acetates of primary and secondary alcohols and phenols.The limitations we found in the use of this reagent include the lack of cleavage of esters sterically hindered around the carboxyl carbon and the carbinol group (i.e., esters of tertiary alcohols) and in carboxylic esters that contain a fluoroalkyl substituent.A resonable mechanistic explanation is discussed to account for the reaction pathway of the acyloxygen cleavage of (-)-(1R)-menthyl acetate.
- Salomon, Claudio J.,Mata, Ernesto G.,Mascaretti, Oreste A.
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p. 7259 - 7266
(2007/10/02)
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- Organic reactions in a solid matrix-VII sodium on alumina: A convenient reagent for reduction of ketones, esters and oximes
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Sodium dispersed on alumina is described and evaluated as a convenient off-the-shelf reagent (in a wax-coated form) for reduction of ketones, esters and oximes. While isopropanol is the preferred proton donor for the reduction of ketones and oximes, t-butanol is the alcohol of choice for the reduction of esters.
- Singh, Satendra,Dev, Sukh
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p. 10959 - 10964
(2007/10/02)
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