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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)

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)

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
(2020/01/11)

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.
(2020/09/09)

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.
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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
p. 550 - 557
(2017/08/26)

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.
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Paragraph 0043-0051

(2017/01/19)

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 (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
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.
p. 1327 - 1331
(2016/02/23)

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.
p. 1327 - 1331
(2015/11/10)

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)

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
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
p. 2812 - 2819
(2007/10/03)

The effects of added ammonium chloride in the reductive amination of some carbonyl compounds over Ru and Pd catalysts
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
p. 2105 - 2109
(2007/10/03)

Al-isopropoxydiisobutylalane: A study of the effect of solvent on the rate and stereoselectivity of cyclic ketone reduction
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.
p. 9289 - 9291
(2007/10/03)

Hydrolysis of Alkenyl Esters and Ethers Catalyzed by Metal Complexes
(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
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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(2008/06/13)

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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(2008/06/13)

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)

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)

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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(2008/06/13)

Stereocontrolled synthesis of novel enantiomerically pure sulfides and selenides from (+)-camphor and (+)-camphor-10-sulfonyl chloride
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.
p. 9611 - 9622
(2007/10/03)

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
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
p. 1385 - 1399
(2007/10/03)

Chiral Synthesis via Organoboranes. 42. Selective Reductions. 57. Efficient Kinetic Resolution of Representative α-Tertiary Ketones with B-Chlorodiisopinocampheylborane
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.
p. 88 - 94
(2007/10/03)

Chiral synthesis via organoboranes. 43. Selective reductions. 58. Reagent-controlled diastereoselective reduction of (+)- and (-)-α-chiral ketones with (+)- and (-)-B-chlorodiisopinocampheylborane
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.
p. 95 - 99
(2007/10/03)

Perfume compositions
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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(2008/06/13)

Ketone Reduction by Titanocene Borohydride
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Barden, Michael C.,Schwartz, Jeffrey
p. 5963 - 5965
(2007/10/03)

Intramolecular vs. intermolecular induction in the diastereoselective catalytic reduction of enantiomerically pure ketones with borane in the presence of cyclic β-amino alcohols
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
p. 3063 - 3070
(2007/10/03)

Synthesis of chiral diazanedicarboxylate and diazenedicarboxylate esters: electrophilic amination reactions of achiral ester and amide enolates
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.
p. 1945 - 1950
(2007/10/02)

Deodorant compositions
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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(2008/06/13)

Dimethoxybenzoin Carbonates: Photochemically-Removable Alcohol Protecting Groups Suitable for Phosphoramidite-Based DNA Synthesis
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Pirrung, Michael C.,Bradley, Jean-Claude
p. 1116 - 1117
(2007/10/02)

Copper(II) exchanged cation exchange resin: Useful activator in the reduction of ketones
A copper(II) exchanged cation exchange resin has been used as support for reduction of ketones with sodium borohydride. Supported Cu(II) ions activate the reduction of ketones to a large extent and control the stereochemistry of reductions of cyclic ketones resulting in preponderance of equatorial alcohol in most cases.
Sarkar,Rao,Ram
p. 291 - 296
(2007/10/02)

Sodium borohydride reduction of capmphor and menthone in inclusion complexes of β-cyclodextrin
Sodium borohydride reduction of camphor and menthone in inclusion complexes of β-cyclodextrin show not only differences in proportion of alcohols formed but also profound influence of β-cyclodextrin in modifying diastereoselectivity and enantioselectivity.
Divakar, S.,Narayan, M. S.,Shaw, A. K.
p. 387 - 389
(2007/10/02)

Organic reactions in a solid matrix-VII sodium on alumina: A convenient reagent for reduction of ketones, esters and oximes
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
p. 10959 - 10964
(2007/10/02)

Treating the camphors with potassium in liquid ammonia leads to a double Horeau duplication
When potassium dissolves in solutions of the enantiomeric camphors R-1 and S-1, variously enantioenriched camphors (1), and racemic camphor RS-1 in liquid ammonia/THF at -77°C, potassium alcoholates of the borneols R-2 and S-2 and isoborrieols R-3 and S-3 plus equivalent amounts of the potassium enolates of R-1 and S-1 - enantiomeric, enantioenriched, and racemic - are produced by a transfer of a β-hydrogen from some 1-derived unit to another [a ketyl disproportionate (hydrogen atom transfer)?]; the exact mechanism is still unknown. Hydrolysis gives enantiomeric, racemic, and enantioenriched 1-3. The mole fractions and enantiomeric compositions (ec's) of 2 and 3 were determined and plotted against the ec's of the substrates 1. The extremes of the resulting three curves are defined by the enantiomers R-1 and S-1 leading to about 1/1 mixtures of R-2 and R-3 and S-2 and S-3, respectively, and the turning points by RS-1 leading to a 9/1 mixture of RS-2 and RS-3. The ec vs ec curve is close to linear in the case of 2 and strongly nonlinear in the case of 3: from enantioenriched substrates 1, one obtains isoborneols 3 with ec's that are strongly amplified with respect to the ec's of the substrates. Fitting the plots into a statistical kinetic model suggests (1) that 3 is formed via one homochiral process (involving units with the same chirality) and 2 via a combination of second homochiral process with a single heterochiral one (involving units with opposite chirality), (2) that the rate-determining steps in these processes are fourth order with respect to the substrates 1 (!), and (3) that all parallel steps have similar or identical rate constants. The homochiral process that leads to 3 amounts to a double Horeau duplication. Statistical oligomerization or condensation of enantioenriched monomers to short oligomers leads to homochiral oligomers with strongly amplified ec. (+)-Camphor R-1 (ec 99.6%) and (-)-camphor S-1 (ec 98.3%) from the chiral pool were not quite enantiopure.
Rautenstrauch, Valentin,Mégard, Patrick,Bourdin, Bernadette,Furrer, Anton
p. 1418 - 1428
(2007/10/02)

Reduction of ketones with polydibenzo-18-crown-6-borohydride
Polydibenzo-18-crown-6-(P-DB-18-C-6), a condensation polymer of dibenzo-18-crown-6 and formaldehyde has ben used as support for borohydride ions in the reduction of few cyclic and acyclic ketones. The reagent has been found to be more stereoselective than dibenzo-18-crown-6-borohydride in the reduction of cyclic ketones. 4-t-butylcyclohexanone has been converted exclusively (100%) to trans-4-t-butylcyclohexanol.
Sarkar,Rao, Br
p. 2157 - 2160
(2007/10/02)

1,8-Diazabicycloundec-7-ene as a Mild Deprotective Agent for Acetyl Groups
A simple acetyl cleavage is described.The method showed selective acetyl deprotection of polyfunctionalized molecules.
Baptistella, Lucia Helena B.,Santos, Jose Fernando dos,Ballabio, Karin Cristina,Marsaioli, Anita Jocelyne
p. 436 - 438
(2007/10/02)

REDUCTIVE COUPLING OF (R)-(+)-CARVONE AND (+)-CAMPHOR BY THE TiCl4-Mg REAGENT. X-RAY CRYSTAL STRUCTURE OF (+)-(1S, 5R, 1'S, 5'R)-CARVONE PINACOL
The reductive coupling of (R)-(+)-carvone by TiCl4-Mg-tBuOH leads to (+)-(1S, 5R, 1'S, 5'R)-carvone pinacol 3 (70 percent).In presence of pentane, (-)-(1R, 5R, 1'R, 5'R)-carvone pinacol 4 (50 percent) and ketol 5 (15 percent) are isolated.Isoborneol (58 percent) and borneol (32 percent) result of the reduction of (+)-camphor with the same reagent.
Pierrot, Marcel,Pons, Jean-Marc,Santelli, Maurice
p. 5925 - 5928
(2007/10/02)

Enantioselectivity in the Biotransformation of Mono- and Bicyclic Monoterpenoids with the Cultured Cells of Nicotiana tabacum
The biotransformation of the enantiomeric pairs of p-menthane and bicyclo and heptane derivatives with the cultured cells of Nicotiana tabacum was investigated.It was found that (i) the cultured cells discriminate the enantiomers of p-menthan-2-ol and bicycloheptan-2-ol and bicycloheptan-3-ol derivatives, and enantioselectively convert these alcohols to the corresponding ketones, (ii) the cells reduce the carbonyl group of p-methan-2-one derivatives to a high extent, but not that of p-menthan-3-ones, and (iii) the cells discriminate the enantiomers of bicyclohept-2-en-4-one (verbenone) and enantioselectively reduce the C-C double bond of the (1S,5S)-enantiomer.
Hamada, Hiroki
p. 869 - 878
(2007/10/02)

Vapor-Phase Reduction of Aldehydes and Ketones with 2-Propanol over Hydrous Zirconium Oxide
Vapor-phase reduction of aldehydes and ketones with 2-propanol was carried out over hydrous zirconium oxide.The reduction proceeded efficiently to give corresponding alcohols.The oxide worked continuously for 10 h without being inactivated.
Shibagaki, Makoto,Takahashi, Kyoko,Kuno, Hideyuki,Kawakami, Hiroshi,Matsushita, Hajime
p. 1633 - 1636
(2007/10/02)

A NEW CLASS OF STEREOSELECTIVE REDUCING AGENTS, POTASSIUM 9-ALKYL-9-BORATABICYCLONONANES
A new class of reducing agents, potassium 9-alkyl-9-boratabicyclononanes (K 9-R-9-BBNHs) was examined its stereoselectivity toward cyclic ketones.Among these, K 9-TB-9-BBNH reveals the most favorable stereoselectivity, comparable to that by lithium trisiamylborohydride at 0 deg C.
Cha, Jin Soon,Yoon, Mal Sook,Kim, Young Shick,Lee, Kwang Woo
p. 1069 - 1070
(2007/10/02)

ENANTIOSPECIFIC HYDROLYSIS OF ACETATES OF RACEMIC MONOTERPENIC ALCOHOLS BY SPIRODELA OLIGORRHIZA
Acetates of racemic menthol, borneol, trans-2-hydroxy-trans-dihydropinol, cis-2-hydroxy-trans-dihydropinol and trans-2-hydroxy-cis-dihydropinol undergo enantiospecific hydrolysis in cultures of Spirodela oligorrhiza.R Alcohols are formed faster than S.Absence of light inhibits hydrolysis of the first two acetates.Key Word Index - Spirodela oligorrhiza; Lemnaceae; duckweed; biotransformation; (+/-)-menthyl acetate; (+/-)-bornyl acetate; (+/-)-trans-2-acetoxy-trans-dihydropinol; (+/-)-cis-2-acetoxy-trans-dihydropinol; (+/-)-trans-2-acetoxy-cis-dihydropinol.
Pawlowicz, Pawel,Piatkowksi, Krzysztof,Siewinski, Antoni
p. 2809 - 2812
(2007/10/02)

DISSOLVING METAL REDUCTIONS OF KETONES: COMMENTS ON THE DIANION MECHANISM
The reduction of (+)-camphor using Li, Na, and K in THF with sonication is reported.These reductions give the same results as those obtained in NH3.The mechanism of these reactions is discussed.
Huffman, John W.,Liao, Wen-Pang,Wallace, Richard H.
p. 3315 - 3318
(2007/10/02)

ENANTIOSELECTIVITY IN CAMPHOR PINACOLISATION
Total enantioselectivity has been observed in pinacol formation using Li/THF. (+) Camphor and (+/-) Camphor give the optically active and racemic form of a single pinacol whose stereochemistry has been established as endo:endo by X-ray analysis.An exo:endo pinacol is formed as the sole product if camphor is added to Li/NH3.Tentative mechanism is proposed.
Pradhan, Suresh K.,Thakker, Krishanlal R.,McPhail, Andrew T.
p. 1813 - 1816
(2007/10/02)

ENANTIOSELECTIVITY IN THE HYDROLYSIS OF BICYCLIC MONOTERPENE ACETATES WITH THE CULTURED CELLS OF NICOTIANA TABACUM
Key Word Index - Nicotiana tabacum; Solanaceae; tissue culture; biotransformation; hydrolysis; enantioselectivity; bicyclic monoterpene acetates.The enantioselectivity in the hydrolysis of bornyl acetate; isobornyl acetate and isopinocampheyl acetate with the cultured cells of Nicotiana tabacum was investigated.The cultured cells were found to have the ability to hydrolyse enantioselectively the acetates, of which the configuration at the carbon atom bearing the acetoxyl group is R.
Suga, Takayuki,Hirata, Toshifumi,Izumi, Shunsuke
p. 2791 - 2792
(2007/10/02)

Thermally Induced Redox Reaction of Carbonyl Compounds and Alcohols in a Radical Chain Reaction
Carbonyl compounds are reduced by alcohols in a thermally initiated radical chain reaction.The reaction of 4-isopropylbenzaldehyde (1i) and 2-propanol (2) has been studied kinetically and is first order with respect to 1i as well as to 2 (kexp. = 7.56 +/- 0.05 - 125 +/- 1/Θ; Θ = 2.303 * R * T in kJ/mol).The results can be satisfactorily explained in terms of a symproportionation of 1i and 2 to give two hydroxylalkyl radicals to initiate the radical chain reaction.This initiation reaction is very slow.The kinetic chain length is very large, ca. 107 at 200 deg C.Kinetic isotopic effects kH/kD of two different metathesis reactions of the radical chain have been measured.The Hammett correlation gives ρ = -0.62 (160 deg C).
Malwitz, Dietmar,Metzger, Juergen O.
p. 3558 - 3575
(2007/10/02)