- Tellurium in the 'no-solvent' organic synthesis of allylic alcohols
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Elemental tellurium can be reduced by rongalite (HOCH2SO2Na·2H2O)-KOH in the solid phase by application of ultrasound or by microwave irradiation. Without solvent, the organic substrate leg sulfonate ester of an oxiranemethanol) is added with further sonication or irradiation to yield the desired organic product leg allylic alcohols) and elemental Te which may be recycled Phase-transfer conditions (water-toluene) also are satisfactory.
- Xu, Qinyu,Chao, Bin,Wang, Yongmei,Dittmer, Donald C.
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Read Online
- Lewis acid promoted highly stereoselective rearrangement of 2,3-aziridino alcohols: A new efficient approach to β-amino carbonyl compounds
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Equation Presented n=0,1 R1, R2 = H, alkyl, aryl A new Lewis acid promoted rearrangement reaction of 2,3-aziridino alcohols was discovered, which involved the highly stereoselective construction of a diastereogenic quaternary carbon
- Wang, Bao Min,Song, Zhen Lei,Fan, Chun An,Tu, Yong Qiang,Shi, Yian
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Read Online
- Proton-accelerated Lewis acid catalysis for stereo- And regioselective isomerization of epoxides to allylic alcohols
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The isomerization of epoxides to allylic alcohols was developedviaproton-accelerated Lewis acid catalysis. The addition oftBuOH as a proton source is the key to the efficient catalytic cycle. Trisubstituted epoxides, including enantioenriched derivatives, were selectively converted to secondary-allylic alcohols without loss of enantiopurity.
- Baba, Misako,Hayashi, Satoshi,Hirabe, Rina,Noji, Masahiro,Takanami, Toshikatsu
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supporting information
p. 7104 - 7107
(2021/07/28)
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- Nazarov cyclization of divinyl and arylvinyl epoxides: Application in the synthesis of resveratrol-based natural products
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New variation in the Nazarov cyclization has been developed by preparing divinyl and arylvinyl epoxides as pentadienyl cation precursors for the first time. Highly substituted cyclopentadienes, hydrindienes, and indenes were synthesized to demonstrate the compatibility of this reaction with substrates bearing a variety of substitutions and having different types of epoxides. Application of this method in the synthesis of resveratrol-based natural products was also demonstrated.
- Sudhakar, Gangarajula,Satish, Kovela
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supporting information
p. 6475 - 6480
(2015/04/22)
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- Kinetic resolution of aryl alkenylcarbinols catalyzed by Fc-PIP
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An effective kinetic resolution of a variety of aryl alkenylcarbinols catalyzed by nonenzymatic acyl transfer catalyst Fc-PIP was developed, affording corresponding unreacted alcohols in good to excellent ee value up to 99% and with selectivity factors up to 24.
- Hu, Bin,Meng, Meng,Jiang, Shanshan,Deng, Weiping
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p. 1289 - 1294
(2012/08/28)
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- QUINAZOLINONE-TYPE COMPOUNDS AS CRTH2 ANTAGONISTS
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This application provides for compounds of the formula Formula I or a pharmaceutically acceptable salt thereof, wherein the individual variables are defined herein, as well as processes to prepare these compounds, pharmaceutical compositions comprising the same and their use in treating disease state associated with the CRTH2 receptor.
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Page/Page column 116
(2012/05/04)
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- Manganese(III) acetate mediated oxidative radical cyclizations. Toward vicinal all-carbon quaternary stereocenters
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Manganese(III) acetate mediated oxidative radical cyclizations have been used to synthesize a range of densely functionalized and sterically congested cyclopentane-lactones. A number of the resulting lactones contain vicinal all-carbon quaternary stereocenters adjacent to a tertiary benzylic stereocenter and are formed with high levels of stereocontrol.
- Logan, Angus W.J.,Parker, Jeremy S.,Hallside, Michal S.,Burton, Jonathan W.
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supporting information; experimental part
p. 2940 - 2943
(2012/08/28)
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- Palladium-catalyzed cross-coupling of unactivated alkenes with acrylates: Application to the synthesis of the C13-C21 fragment of palmerolide A
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Diene to meet: A palladium-catalyzed cross-coupling reaction between alkyl-substituted olefins and acrylates gives the corresponding butadienes in moderate yield and stereoselectivity. This atom-economical reaction, which forms C sp 2-C sp 2 bonds, tolerates a wide range of allylic and homoallylic alcohols, and acrylates (see scheme; TIPS =triisopropylsilyl). The methodology was applied to the synthesis of the C13-C21 fragment of palmerolide A.
- Wen, Zhen-Kang,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 13284 - 13287,4
(2012/12/12)
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- Palladium-catalyzed cross-coupling of unactivated alkenes with acrylates: Application to the synthesis of the C13-C21 fragment of palmerolide A
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Diene to meet: A palladium-catalyzed cross-coupling reaction between alkyl-substituted olefins and acrylates gives the corresponding butadienes in moderate yield and stereoselectivity. This atom-economical reaction, which forms C sp 2-C sp 2 bonds, tolerates a wide range of allylic and homoallylic alcohols, and acrylates (see scheme; TIPS =triisopropylsilyl). The methodology was applied to the synthesis of the C13-C21 fragment of palmerolide A.
- Wen, Zhen-Kang,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 13284 - 13287
(2013/01/15)
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- Synthesis of the c1-c14 fragment of sarcoglaucol-16-one via z -selective ando-type horner-wadsworth-emmons olefination
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A synthetic strategy involving a Z-selective Horner-Wadsworth-Emmons olefination was developed for the preparation of the sarcoglaucolone precursor methyl (2Z,6E)-8-(methoxymethoxy)-6-methyl-2-[(3E)-4-methyl-5-oxopent-3-enyl]-9- [(trimethylsilyl)methyl]deca-2,6,9-trienoate. The target compound was isolated in a E/Z ratio of 17:83 Georg Thieme Verlag Stuttgart New York.
- Gastl, Christoph,Laschat, Sabine
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supporting information; experimental part
p. 2643 - 2651
(2010/10/01)
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- Titanocene-promoted eliminations on epoxy alcohols and epoxy esters
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The reaction of a series of 2,3-epoxy alcohols and the corresponding formates, acetates, and benzoates promoted by Cp2TiCl has been studied. The different outcome of the reaction of epoxy derivatives has been rationalized in terms of mechanistically biased processes. After homolytic oxirane cleavage, four main types of reaction were found: dehydroxylation, decarboxylation, dehydrogenation, and deoxygenation. The reaction products varied according to the substitution pattern. The radical nature of these eliminations is demonstrated.
- Fernandez-Mateos, Alfonso,Madrazo, Soledad Encinas,Teijon, Pablo Herrero,Gonzalez, Rosa Rubio
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supporting information; experimental part
p. 856 - 861
(2010/04/05)
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- Enantioselective synthesis of allylic alcohols via an oxazaborolidinium ion catalyzed diels-alder/retro-diels-alder sequence
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A triflimide-activated oxazaborolidine catalyst successfully promoted the asymmetric Diels-Alder reaction of 9-methylanthracene with methacrolein in high regio- and enantioselectivity. The cycloadduct obtained was subsequently used as a chiral template to
- Jones, Simon,Valette, Damien
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supporting information; experimental part
p. 5358 - 5361
(2010/01/19)
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- [(NHC)Au1]-catalyzed rearrangement of allylic acetates
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Equation Presented [(NHC)AuCl] complexes (NHC = N-heterocyclic carbene), in conjunction with a silver salt, were found to efficiently catalyze the rearrangement of allylic acetates under both conventional and microwave-assisted heating. The optimization of several reaction parameters (solvent, silver salt, and ligand) as well as a study of the reaction scope are reported. The steric hindrance of the ligand bound to gold was found crucial for the outcome of the reaction as only extremely bulky ligands permitted the isomerization.
- Marion, Nicolas,Gealageas, Ronan,Nolan, Steven P.
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p. 2653 - 2656
(2008/02/09)
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- A highly enantioselective synthesis of chiral allylic alcohols by asymmetric addition of novel mixed reagents of trialkenylbismuthines/dialkylzincs to aldehydes
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A novel mixture of reagents of trialkenylbismuthines/dialkylzincs was developed and applied toward the synthesis of chiral allylic alcohols. The chiral β-amino alcohols catalyzed addition of the mixed reagents of trialkenylbismuthines/dialkylzincs to alde
- Sato, Itaru,Asakura, Noriaki,Iwashita, Taizo
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p. 2638 - 2642
(2008/04/05)
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- Highly diastereoselective hydrostannylation of allyl and homoallyl alcohols with dibutyl(trifluoromethanesulfoxy)stannane
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Dibutyl(trifluoromethanesulfoxy)stannane (Bu2Sn(OTf)H, 1a) was found to be very valuable for highly diastereoselective homolytic hydrostannylation of allyl and homoallyl alcohols. α,β-Disubstituted allyl alcohols and α,γ-disubstituted homoallyl alcohols were converted into γ- and δ-stannylated alcohols with high 1,2-syn and 1,3-syn diastereoselectivity, respectively. The origin of the stereochemical outcomes can be rationalized by conformational fixation of the intermediary β-stannylalkyl radical by coordination of the hydroxy group to the Lewis acidic tin center. Copyright
- Miura, Katsukiyo,Wang, Di,Hosomi, Akira
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p. 9366 - 9367
(2007/10/03)
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- Vanadium-catalyzed selenide oxidation with in situ [2,3] sigmatropic rearrangement (SOS reaction): Scope and asymmetric applications
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A vanadium-catalyzed method for the oxidation of prochiral aryl, allylic selenides with tandem sigmatropic rearrangement has been developed. This protocol has been screened on a series of substrates to test for its generality and effectiveness. The applicability of this methodology to the synthesis of enantiomerically enriched allylic alcohols has been studied on a series of chiral oxazole-containing systems with a diastereomeric ratio (d.r.) of up to 85 : 15. The chiral transfer observed in the allyl alcohol products is the result of a net 1,9- and/or 1,10-induction. Finally, the first example of a selenium-oxygen nonbonding interaction in oxazole-containing selenide appears to have been observed via X-ray crystal analysis.
- Campbell Bourland,Carter, Rich G.,Yokochi, Alexandre F. T.
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p. 1315 - 1329
(2007/10/03)
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- Bifunctional molecular linchpins: A three-component coupling protocol employing 2-bromoallyltrimethylsilane
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A new three-component coupling protocol, exploiting 2- bromoallyltrimethylsilane as a bifunctional linchpin, has been developed. The reaction sequence entails the following steps: lithiation of the vinyl bromide, addition of an aromatic or aliphatic aldehyde, execution of a solvent controlled 1,4-Brook rearrangement induced by HMPA to generate an allyl anion, and addition of a reactive second electrophile. Yields are moderate to good.
- Smith III, Amos B.,Duffey, Matthew O.
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p. 1363 - 1366
(2007/10/03)
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- On the Reactivity of o-Lithioaryl Ethers: Tandem Anion Translocation and Wittig Rearrangement
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(matrix presented) Allyl and benzyl 2-lithioaryl ethers, generated by bromine-lithium exchange in THF, undergo a new tandem anion translocation-[1,2]-Wittig rearrangement allowing the isolation of the corresponding benzylic alcohols.
- Barluenga, Jose,Fananas, Francisco J.,Sanz, Roberto,Marcos, Cesar,Trabada, Marta
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p. 1587 - 1590
(2007/10/03)
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- Compounds having protected hydroxy groups
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The present invention relates to compounds with protected hydroxy groups of formula (I) These compounds are precursors for organoleptic agents, such as fragrances, and masking agents and for antimicrobial agents. When activated, the compounds of formula (I) are cleaved and form one or more organoleptic and/or antimicrobial compounds.
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- Beta-ketoester compounds
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The beta-ketoesters of formula I are useful as precursors for organoleptic compounds, especially for flavors, fragrances and masking agents and antimicrobial compounds.
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- Ketone precursors for organoleptic compounds
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The invention discloses ketones of formula I: wherein, Y is an optionally substituted alkyl, cycloalkyl, or cycloalkylalkyl, wherein each alkyl group is straight or branched and each alkyl and cycloalkyl group is saturated or unsaturated; R1is hydrogen or a C1-6alkyl group that is substituted, saturated or unsaturated, straight or branched; A is a chromophoric substituted aromatic ring or ring system; n is an integer; and with the proviso that formula I is not 2-ethoxy-1-phenyl-ethanone. These compositions are useful for the delivery of organoleptic compounds, especially of flavors, fragrances, masking agents and antimicrobial compounds.
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- The first vanadium-catalyzed oxidation of aryl allylic selenides with in situ [2,3] sigmatropic rearrangement
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The efficient synthesis of a series of 2°allylic alcohols from a vanadium-catalyzed oxidation of suitably disposed allylic selenides with tandem [2,3] sigmatropic rearrangement is outlined.
- Carter,Bourland
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p. 2031 - 2032
(2007/10/03)
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- ENZYMATIC SYNTHESIS OF (1R,2S)- AND (1S,2R)-2-METHYL-2,3-EPOXY-1-PHENYLPROPANOLS
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(1R,2S)- and (1S,2R)-2-methyl-2,3-epoxy-1-phenylpropanols were prepared from α-methylcinnamyl chloride by use of baker's yeast and lipase PS.
- Takeshita, Mitsuhiro,Yaguchi, Reiko,Unuma, Yukiko
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p. 967 - 974
(2007/10/02)
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- A Tellurium Transposition Route to Allylic Alcohols: Overcoming Some Limitations of the Sharpless-Katsuki Asymmetric Epoxidation
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Good yields of enantiomeric allylic alcohols can be obtained in high enantiomeric excess (ee) by combining Sharpless-Katsuki asymmetric epoxidation process (SAE) with tellurium chemistry.The advantages of the tellurium process are as follows: (1) the 50percent yield limitation on the allylic alcohol in the Sharpless kinetic resolution (SKR) can be overcome; (2) allylic tertiary alcohols which are unsatisfactory substrates in the SKR can be obtained in high optical purity; (3) optically active secondary allylic alcohols with tertiary alkyl substituents (e.g. tert-butyl) at C-1 can be obtained in high ee; (4) optically active sterically congested cis secondary alcohols can be obtained in high ee; and (5) the nuisance of the slow SAE of some vinyl carbinols can be avoided.The key step in the reaction sequence is either a stereospecific 1,3-transposition of double bond and alcohol functionalities or an inversion of the alcohol configuration with concomitant deoxygenation of the epoxide function in epoxy alcohols.Trans secondary allylic alcohols can be converted to cis secondary allylic alcohols by way of erythro epoxy alcohols (glycidols); threo glycidyl derivatives are converted to trans secondary allylic alcohols.These transformations are accomplished by the action of telluride ion, generated in situ from the element, on a glycidyl sulfonate ester.Reduction of elemental Te is conveniently done with rongalite (HOCH2SO2Na) in an aqueous medium.This method is satisfactory when Te2- is required to attack at primary carbon site of a glycidyl sulfonate.In cases where Te2- is required to attack a secondary carbon site, reduction of the tellurium must be done with NaBH4 or LiEt3BH.Elemental tellurium is precipitated during the course of the reactions and can be recovered and reused.
- Dittmer, Donald C.,Discordia, Robert P.,Zhang, Yanzhi,Murphy, Christopher K.,Kumar, Archana,et al.
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p. 718 - 731
(2007/10/02)
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- VINYLLITHIUMS FROM BUTYL VINYL TELLURIDES AND BIS-VINYL TELLURIDES
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Butyl vinyl tellurides and bis-vinyl tellurides furnish vinyllithiums with retention of configuration in good yields upon treatment with n-butyllithium at -78 deg C.
- Barros, Simone M.,Comasseto, Joao V.,Berriel, Jorge
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p. 7353 - 7356
(2007/10/02)
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- NOVEL SYNTHESIS OF MONOFLUOROCYCLOBUTANES BY THE RING EXPANSION-FLUORINATION OF CYCLOPROPYLMETHANOLS WITH AN AMINE-METAL FLUORIDE-PYRIDINIUM POLY(HYDROGEN FLUORIDE)-COMPLEX
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Various new 1-fluoro-1-alkyl(or aryl)-2-substituted cyclobutanes were synthesized stereoselectively from 1-alkyl(or aryl)cyclopropyl carbinols by the ring expansion-fluorination using (iPr)2-KHF2-(HF)n.Py, and 2
- Kanemoto, Shigekazu,Shimuzu, Makoto,Yoshioka, Hirosuke
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p. 6313 - 6316
(2007/10/02)
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- AZO ANIONS IN SYNTHESIS. USE OF TRITYL- AND DIPHENYL-4-PYRIDYLMETHYLHYDRAZONES FOR REDUCTIVE C-C BOND FORMATION.
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The lithium salts of trityl- and diphenyl-4-pyridylmethyl-hydrazones of both aldehydes and ketones react with electrophiles (alkyl halides, aldehydes, ketones, crotonates) at low temperature to form C-trapped azo compounds; these intermediates decompose homolytically with loss of nitrogen below room temperature and can be diverted in a synthetically useful way to alkanes, alkenes, alcohols or saturated esters.
- Baldwin, Jack E.,Adlington, Robert M.,Bottaro, Jeffrey C.,Kolhe, Jayant N.,Newington, Ian M.,Perry, Matthew W. D.
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p. 4235 - 4246
(2007/10/02)
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- Palladium-catalysed oxidation of alcohols with carbon tetrachloride, formation of 4,4,4-trichloro ketones from allylic alcohols and carbon tetrachlorid
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Pd salts catalyse oxidation of alcohols with CCl4 in the presence of K2CO3. Primary alcohols are oxidised to esters, and secondary alcohols to ketones. CCl4 is converted to CHCl3. The reaction of allylic alcohols bearing a terminal olefinic bond with CCl4 or BrCCl3 in the presence of palladium catalyst at 110° affords 4,4,4-trichloro ketones. At 40°, simple adducts of CCl4 or BrCCl3 having a halohydrin structure are obtained, which are converted to the corresponding trichloro ketones by the catalysis of palladium. Various halohydrins are converted to ketones by Pd catalysis.
- nagashima, Hideo,Sato, Koji,Tsuii, Jiro
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p. 5645 - 5651
(2007/10/02)
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- STUDIES ON β-METHYL-1-AND 3-PHENYL ALLYL CHLORIDES
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The hydrolysis of β-methyl-1-and 3-phenylallyl chlorides (1a and 1b) have been investigated in aqueosus dioxan and the proposed mechanism compared with those reported for the corresponding 1- and 3-phenylallyl chlorides (2a and 2b).Hydrolysis of 1a and 1b proceeds via the same mechanism as 2a and 2b, respectively, with different behavior by the first intermediate.The first intermediate of 1a rearranges to the corresponding conjugated compound through a transition state rather than an intermediate.Theoretical calculations on the carbonium ions of 1 and 2 using a semiempirical MINDO/3 molecular orbital method show that the charge densities on carbon atoms of 1 are nearly the same as those of 2.The main difference is in the bond angle C1-C8-C9.
- Shandala, M. Y.,Khalil, S. M.,Al-Dabbagh, M. S.
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p. 1195 - 1198
(2007/10/02)
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- Azo Anions in Synthesis. Use of Trityl- and Diphenyl-4-pyridylmethyl-hydrazones for Reductive C-C Bond Formation from Aldehydes and Ketones
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The lithium salts for trityl- and diphenyl-4-pyridylmethyl-hydrazones of both aldehydes and ketones react with electrophiles (alkyl halides, aldehydes, and ketones) at low temperature to form C-trapped azo compounds; these intermediates decompose homolytically with loss of nitrogen below room temperature and can be diverted in a synthetically useful way to alkanes, or alkenes, or alcohols.
- Baldwin, Jack E.,Bottaro, Jeffrey C.,Kolhe, Jayant N.,Adlington, Robert M.
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- SELECTIVE GRIGNARD-TYPE CARBONYL ADDITION OF ALKENYL HALIDES MEDIATED BY CHROMIUM(II) CHLORIDE
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Alkenyl (or aryl) iodide (or bromide) is readily reduced with CrCl2 in N,N-dimethylformamide at 25oC to give the corresponding organochromium species which adds selectively to an aldehyde moiety without affecting the coexisting ketone or cyano group of the substrate.
- Takai, Kazuhiko,Kimura, Keizo,Kuroda, Tooru,Hiyama, Tamejiro,Nozaki, Hitosi
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p. 5281 - 5284
(2007/10/02)
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- Determination of Configuration and Conformation of Isoxazolidines by Nuclear Overhauser Effect Difference Spectroscopy
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The configurations of isoxazolidines 2, 3, 5, 7, and 10-12 have been assigned by analysis of NMR coupling constants and by nuclear Overhauser effect difference spectroscopy (NOEDS).The preferred solution conformations of isoxazolidines 3 and 5 were determined to be as in 3A/5A.It is proposed that these conformations are adopted to take advantage of the anomeric effect and to alleviate the unfavorable stereoelectronic lone pair-lone pair interaction in the N-O portion of the molecule (gauche effect).
- DeShong, Philip,Dicken, C. Michael,Staib, Ronald R.,Freyer, Alan J.,Weinreb, Steven M.
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p. 4397 - 4403
(2007/10/02)
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