- Ligand-controlled cobalt-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes
-
The Co-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes were realized by a ligand-controlled strategy. The remote hydroboration with dcype provided borylethers, while xantphos favored the formation of silyl enol ethers.
- Huang, Jiaxin,Li, Jie,Yang, Wen,Zhang, Kezhuo,Zhao, Pei,Zhao, Wanxiang
-
supporting information
p. 302 - 305
(2022/01/03)
-
- Formation of Enol Ethers by Radical Decarboxylation of α-Alkoxy β-Phenylthio Acids
-
Enol ethers are formed by radical decarboxylation of α-alkoxy β-phenylthio acids via the corresponding Barton esters. The phenylthio acids were usually made by the known regioselective reaction of α,β-epoxy acids with PhSH in the presence of InCl3, followed by O-alkylation of the resulting alcohol. In one case, thiol addition to an α,β-unsaturated ethoxymethyl ester was used.
- Palanivel, Ashokkumar,Mubeen, Sidra,Warner, Thomas,Ahmed, Nayeem,Clive, Derrick L. J.
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p. 12542 - 12552
(2019/10/19)
-
- Remote Functionalization of α,β-Unsaturated Carbonyls by Multimetallic Sequential Catalysis
-
The remote functionalization of α,β-unsaturated carbonyls by an array of multimetallic sequential catalytic systems is described. The reactions are triggered by hydrometalation using [Pd-H] or [Ru-H] isomerization catalysts and driven by the formation of thermodynamically more stable 1,2-vinyl arenes. The Pd-catalyzed deconjugative isomerization was combined with a Cu-catalyzed β-borylation of the transiently generated styrenyl derivatives to deliver a range of products that would not be accessible with the use of a single catalyst. [Pd/Cu] catalytic systems were also identified for the highly enantioselective α-hydroboration and α-hydroamination of the styrenyl intermediates. Difunctionalization simultaneously at the benzylic and homobenzylic positions was achieved by combining the isomerization process with Sharpless asymmetric dihydroxylation (SAD) using [Pd/Os] or [Ru/Os] couples. Starting from a simple α,β-unsaturated ester, an isomerization/dihydroxylation/lactonization sequence gave access to a naturally occurring γ-butyrolactone in good yield, with excellent diastereo- and enantioselectivity.
- Romano, Ciro,Fiorito, Daniele,Mazet, Clément
-
supporting information
p. 16983 - 16990
(2019/10/28)
-
- Phosphetane oxides as redox cycling catalysts in the catalytic wittig reaction at room temperature
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Recently, phosphorus redox cycling has gained significant importance for a number of transformations originally requiring the use of stoichiometric amounts of phosphorus reagents. While these methodologies have several benefits, high catalyst loadings (≥10 mol percent) and harsh reaction conditions (T ≥ 100 °C) often limit their versatility and applicability. Herein, we report differently substituted phosphetane oxides as efficient catalysts for the catalytic Wittig reaction. The phosphetane scaffold is easy to modify, and a number of catalysts can be obtained in a simple two-step synthesis. The activity in the Wittig reaction significantly surpasses previously reported phospholane-based catalysts and the reaction can be conducted with catalyst loadings as low as 1.0 mol percent even at room temperature. Furthermore, a Br?nsted acid additive is no longer required to achieve high yields at these mild conditions. A methyl-substituted phosphetane oxide was employed to synthesize 25 different alkenes with yields of up to 97percent. The methodology has a good functional group tolerance and the reaction can be performed starting with alkyl chlorides, bromides, or iodides. Additionally, it was possible to use poly(methylhydrosiloxane) as the terminal reductant in the catalytic Wittig reaction employing 2-MeTHF as a renewable solvent. The intermediates of the Wittig reaction were analyzed by 31P NMR spectroscopy, and in situ NMR experiments confirmed phosphane oxide as the resting state of the catalyst. Further kinetic investigations revealed a striking influence of the base on the rate of phosphane oxide reduction.
- Longwitz, Lars,Spannenberg, Anke,Werner, Thomas
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p. 9237 - 9244
(2019/10/08)
-
- Trifluoromethylation of Unactivated Alkenes with Me3SiCF3 and N-Iodosuccinimide
-
A novel approach to the trifluoromethylation of unactivated alkenes is presented. This reaction is promoted by N-iodosuccinimide (NIS) under visible light irradiation without the need for photocatalysts. The mild conditions allow the direct synthesis of u
- Yang, Xinkan,Tsui, Gavin Chit
-
supporting information
p. 1521 - 1525
(2019/03/07)
-
- The Catalytic Asymmetric Mukaiyama–Michael Reaction of Silyl Ketene Acetals with α,β-Unsaturated Methyl Esters
-
α,β-Unsaturated esters are readily available but challenging substrates to activate in asymmetric catalysis. We now describe an efficient, general, and highly enantioselective Mukaiyama–Michael reaction of silyl ketene acetals with α,β-unsaturated methyl esters that is catalyzed by a silylium imidodiphosphorimidate (IDPi) Lewis acid.
- Gatzenmeier, Tim,Kaib, Philip S. J.,Lingnau, Julia B.,Goddard, Richard,List, Benjamin
-
supporting information
p. 2464 - 2468
(2018/02/06)
-
- Synthesis and evaluation of (E)-2-(5-phenylpent-2-en-4-ynamido)cyclohex-1-ene-1-carboxylate derivatives as HCA2 receptor agonists
-
Novel series of compounds consisting of 2-amidocyclohex-1-ene carboxylate and phenyl parts which are connected by enyne (compounds 2a–f), but-1-yne (compounds 4a–j), and phenylethylene (compounds 5a–f) linkers as HCA2 full agonists were designed and their
- Bobileva, Olga,Ikaunieks, Martins,Duburs, Gunars,Mandrika, Ilona,Petrovska, Ramona,Klovins, Janis,Loza, Einars
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p. 4314 - 4329
(2017/07/22)
-
- Dual Palladium(II)/Tertiary Amine Catalysis for Asymmetric Regioselective Rearrangements of Allylic Carbamates
-
The streamlined catalytic access to enantiopure allylic amines as valuable precursors towards chiral β- and γ-aminoalcohols as well as α- and β-aminoacids is desirable for industrial purposes. In this article an enantioselective method is described that transforms achiral allylic alcohols and N-tosylisocyanate in a single step into highly enantioenriched N-tosyl protected allylic amines via an allylic carbamate intermediate. The latter is likely to undergo a cyclisation-induced [3,3]-rearrangement catalysed by a planar chiral pentaphenylferrocene palladacycle in cooperation with a tertiary amine base. The otherwise often indispensable activation of palladacycle catalysts by a silver salt is not required in the present case and there is also no need for an inert gas atmosphere. To further improve the synthetic value, the rearrangement was used to form dimethylaminosulfonyl-protected allylic amines, which can be deprotected under non-reductive conditions.
- Bauer, Johannes Moritz,Frey, Wolfgang,Peters, René
-
supporting information
p. 5767 - 5777
(2016/04/20)
-
- Toward a Unified Mechanism for Oxoammonium Salt-Mediated Oxidation Reactions: A Theoretical and Experimental Study Using a Hydride Transfer Model
-
A range of oxoammonium salt-based oxidation reactions have been explored computationally using density functional theory (DFT), and the results have been correlated with experimentally derived trends in reactivity. Mechanistically, most reactions involve a formal hydride transfer from an activated C-H bond to the oxygen atom of the oxoammonium cation. Several new potential modes of reactivity have been uncovered and validated experimentally.
- Hamlin, Trevor A.,Kelly, Christopher B.,Ovian, John M.,Wiles, Rebecca J.,Tilley, Leon J.,Leadbeater, Nicholas E.
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p. 8150 - 8167
(2015/09/02)
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- Highly enantioselective copper(i)-catalyzed conjugate addition of 1,3-diynes to α,β-unsaturated trifluoromethyl ketones
-
The conjugate diynylation of α,β-unsaturated trifluoromethyl ketones is carried out in the presence of a low catalytic load (2.5 mol%) of a copper(i)-MeOBIPHEP complex, triethylamine and a terminal 1,3-diyne. Pre-metalation of the terminal 1,3-diyne with stoichiometric or higher amounts of dialkylzinc reagent is not required. The corresponding internal diynes bearing a propargylic stereogenic center are obtained with good yields and excellent enantioselectivities. This journal is
- Sanz-Marco, Amparo,Blay, Gonzalo,Mu?oz, M. Carmen,Pedro, José R.
-
supporting information
p. 8958 - 8961
(2015/05/27)
-
- Oxidative cleavage of allyl ethers by an oxoammonium salt
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A method to oxidatively cleave allyl ethers to their corresponding aldehydes mediated by an oxoammonium salt is described. Using a biphasic solvent system and mild heating, cleavage proceeds readily, furnishing a variety of α,β-unsaturated aldehydes and ketones.
- Kelly, Christopher B.,Ovian, John M.,Cywar, Robin M.,Gosselin, Taylor R.,Wiles, Rebecca J.,Leadbeater, Nicholas E.
-
supporting information
p. 4255 - 4259
(2015/04/14)
-
- Phospholane-catalyzed wittig reaction
-
We identified 2-phenylisophosphindoline 2-oxide as a suitable and potentially tunable catalyst for the catalytic Wittig reaction of aldehydes with activated organohalides. This catalyst was obtained by a straightforward two-step synthesis. Trimethoxysilane proved to be an efficient reducing agent for the in situ generation and regeneration of the catalyst from the corresponding phosphane oxide. Sodium carbonate was identified as a suitable base for the transformation. It is noteworthy that the particle size of the sodium carbonate had a tremendous effect on the outcome of the reaction. Under the optimized reaction conditions, 23 aldehydes were converted into the corresponding alkenes in high isolated yields of up to 88%. Moreover, an asymmetric catalytic Wittig reaction was performed for the desymmetrization of a prochiral diketone.
- Werner, Thomas,Hoffmann, Marcel,Deshmukh, Sunetra
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p. 3286 - 3295
(2015/05/20)
-
- Scope and Limitation of the Microwave-Assisted Catalytic Wittig Reaction
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We have developed a microwave-assisted catalytic Wittig reaction. In this paper, we give full account of the scope and limitations of this reaction. A screening of various commercially available phosphine oxides as precatalysts revealed Bu3P=O to be the most promising candidate. We tested 10 silanes for the in situ reduction of the phosphine oxide to generate Bu3P as the actual catalyst. Different epoxides were tested as masked bases. In this context, cyclohexene oxide as well as butylene oxide proved to be suitable. The reaction could be carried out at 125 C, but higher yields and E/Z selectivities were obtained at 150 °C. Under the optimised reaction conditions, more than 40 examples for the conversion of various aldehydes into the corresponding alkenes are reported. The products were obtained in yields of up to 88 with high E selectivities. Moreover, we also describe the further screening of several chiral phosphines as catalysts for the microwave-assisted enantioselective catalytic Wittig reaction. The scope and limitations of the microwave-assisted catalytic Wittig reaction have been evaluated with respect to the catalyst, silane, solvent, reaction conditions, and substrates.
- Hoffmann, Marcel,Deshmukh, Sunetra,Werner, Thomas
-
p. 4532 - 4543
(2015/07/27)
-
- Asymmetric cascade reaction to allylic sulfonamides from allylic alcohols by palladium(II)/base-catalyzed rearrangement of allylic carbamates
-
A regio- and enantioselective tandem reaction is reported capable of directly transforming readily accessible achiral allylic alcohols into chiral sulfonyl-protected allylic amines. The reaction is catalyzed by the cooperative action of a chiral ferrocene palladacycle and a tertiary amine base and combines high step-economy with operational simplicity (e.g. no need for inert-gas atmosphere or catalyst activation). Mechanistic studies support a Pd II-catalyzed [3,3] rearrangement of allylic carbamates - generated in situ from the allylic alcohol and an isocyanate - as the key step, which is followed by a decarboxylation.
- Bauer, Johannes Moritz,Frey, Wolfgang,Peters, Rene
-
supporting information
p. 7634 - 7638
(2014/08/05)
-
- First Microwave-Assisted Catalytic Wittig Reaction
-
We introduce a novel catalytic Wittig reaction based on an inexpensive and readily available phosphane oxide as a precatalyst. The performance of the reaction under microwave irradiation led to significantly improved yields and reaction rates relative to those obtained under conventional heating. Moreover, herein we enclose the first example of the asymmetric catalytic Wittig reaction based on a chiral phosphane as the catalyst.
- Werner, Thomas,Hoffmann, Marcel,Deshmukh, Sunetra
-
supporting information
p. 6873 - 6876
(2016/02/19)
-
- Attachment of carbonyl functionalities onto olefins via copper-promoted radical reaction of dichloromethylcyanides
-
Chemo- and regioselective protocols for attachment of various carbonyl functionalities onto unactivated olefins have been developed. Atom transfer radical reactions of Cl3CCN, Cl2C(R)CN, and Cl 2C(CN)2 were all promoted efficiently by a catalytic amount of CuCl and 1,1′-bis(diphenylphosphino)ferrocene to introduce chloromethylcyanide and chloride units to the C-C double bonds. Conversion of the chloromethylcyanide to the carbonyl functionalities (e.g., aldehydes, ketones and esters), and subsequent double bond reconstruction through elimination of HCl resulted in selective formation of the carbonyl-conjugated E-olefins.
- Kamijo, Shin,Yokosaka, Shinya,Inoue, Masayuki
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p. 5290 - 5296
(2012/08/14)
-
- A microwave-assisted deconjugative esterification of α,β- unsaturated carboxylic acids through α,β-unsaturated ketene intermediates
-
A facile synthetic approach to β,γ-unsaturated esters by deconjugative esterification of α,β-unsaturated carboxylic acids with alcohols in the presence of 1,3-dicyclohexylcarbodiimide (DCC), Me 3N·HCl, and Me2NEt is described. The on
- Sano, Shigeki,Ichikawa, Takashi,Nakao, Michiyasu,Nagao, Yoshimitsu
-
scheme or table
p. 68 - 69
(2012/03/11)
-
- Manganese(III)-mediated phosphinoyl radical reactions for stereoselective synthesis of phosphinoylated tetrahydronaphthalenes
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Reactions of diphenylphosphinoyl radicals with 5-aryl-2-pentenoates or β-phenylethylene styrenes generate trans-substituted tetrahydronaphthalenes through a cascade reaction sequence.
- Pan, Xiang-Qiang,Wang, Lu,Zou, Jian-Ping,Zhang, Wei
-
experimental part
p. 7875 - 7877
(2011/09/12)
-
- Ester- and ketone-substituted (±)-1-alkyl-6-nitro-1,2,3,4- tetrahydroquinolines by a tandem SNAr-Michael reaction
-
(Chemical Equation Presented) A synthesis of ester- and ketone-substituted (±)-1-alkyl-6-nitro-1,2,3,4-tetrahydroquinolines has been developed from 2-pentenoates and 2-penten-1-ones substituted at C5 by a 2-fluoro-5-nitrophenyl group. The cyclization involves an SNAr reaction followed by a Michael addition that occurs exo to the final ring. A previously reported version of this annulation proceeded by an initial endo Michael addition (acceptor became part of the final ring) followed by an SNAr ring closure. The current reactions proceed in 82-97% yields in DMSO using primary amines that are unbranched at the α carbon. The synthesis of the reaction substrates as well as process optimization, mechanistic studies to elucidate the reaction chronology and comparisons with the endo Michael variant are presented.
- Bunce, Richard A.,Lee, Eric J.
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experimental part
p. 1176 - 1182
(2010/11/16)
-
- Unravelling the olefin cross metathesis on solid support. Factors affecting the reaction outcome
-
Olefin cross metathesis on solid support under a variety of conditions is described. A comprehensive analysis considering diverse factors governing the reaction outcome gives a series of patterns for the application of this useful methodology in organic synthesis. If the intrasite reaction is not possible, homodimerization of the soluble olefin is crucial. When the homodimer is less reactive than its monomer, reaction outcome depends on the homodimerization rate, which, in turn, depends on the precatalyst used and the reaction conditions. If the site-site interaction is a feasible process, the cross metathesis product is obtained exclusively when the newly-formed double bond is resilient to further metathetic events. Taking into account these considerations, we have demonstrated that excellent results in terms of cross metathesis coupling can be obtained under the optimized conditions, and that microwave irradiation is also an interesting alternative for the development of a practical and energy-efficient cross metathesis on solid support.
- Poeylaut-Palena, Andres A.,Mata, Ernesto G.
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experimental part
p. 3947 - 3956
(2010/09/17)
-
- The asymmetric aza-claisen rearrangement: development of widely applicable pentaphenylferrocenyl palladacycle catalysts
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Systematic studies have been performed to develop highly efficient catalysts for the asymmetric aza-Claisen rearrangement of trihaloacetimidates. Herein, we describe the stepwise development of these catalyst systems involving four different catalyst generations finally resulting in the development of a planar chiral pentaphenylferrocenyl oxazoline palladacycle. This complex is more reactive and has a broader substrate tolerance than all previously known catalyst systems for asymmetric aza-Claisen rearrange-ments. Our investigations also reveal that subtle changes can have a big impact on the activity. With the enhanced catalyst activity, the asymmetric aza-Claisen rearrangement has a very broad scope: the methodology not only allows the formation of highly enantioenriched primary allylic amines, but also secondary and tertiary amines; al-lylic amines with N-substituted quaternary stereocenters are conveniently accessible as well. The reaction conditions tolerate many important functional groups, thus providing stereoselective access to valuable functionalized building blocks, for example, for the synthesis of unnatural amino acids. Our results suggest that face-selective olefin coordination is the enantioselectivitydetermining step, which is almost exclusively controlled by the element of planar chirality.
- Fischer, Daniel F.,Barakat, Assem,Xin, Zhuo-Qun,Weiss, Matthias E.,Peters, Rene
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supporting information; scheme or table
p. 8722 - 8741
(2010/03/31)
-
- Stereoselective olefination reactions promoted by Rieke manganese
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A study of the advantages of using manganese, an inexpensive and nontoxic metal, to perform stereoselective β-elimination reactions and to promote sequential olefination reactions of aldehydes to obtain α,β- unsaturated esters and amides is presented. Various elimination reactions, all of them characterized by occurring with complete stereoselectivity and in high yields, were performed using active manganese (Mn*) as metalating agent. This ability of manganese has been applied to develop a novel and direct synthesis of (E)-α,β-unsaturated esters or amides and (Z)-α,β-unsaturated α-halo esters and α-choroamides through a Mn*-mediated sequential olefination protocol of aldehydes with dichloro esters or amides and trihalo esters or trichloroamides, respectively. Georg Thieme Verlag Stuttgart.
- Concellon, Jose M.,Rodriguez-Solla, Humberto,Del Amo, Vicente,Diaz, Pamela
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experimental part
p. 2634 - 2645
(2009/12/06)
-
- Highly (E)-selective wadsworth-emmons reactions promoted by methylmagnesium bromide
-
(Chemical Equation Presented) An experimentally simple protocol for the very highly (E)-selective Wadsworth-Emmons reaction [(E):(Z) selectivities in excess of 180:1 in some cases] of a range of straight-chain and branched aliphatic, substituted aromatic, and base-sensitive aldehydes via reaction with an alkyl diethylphosphonoacetate and MeMgBr is reported.
- Claridge, Timothy D. W.,Davies, Stephen G.,Lee, James A.,Nicholson, Rebecca L.,Roberts, Paul M.,Russell, Angela J.,Smith, Andrew D.,Toms, Steven M.
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supporting information; experimental part
p. 5437 - 5440
(2009/06/18)
-
- Solid-supported cross metathesis and the role of the homodimerization of the non-immobilized olefin
-
(Chemical Equation Presented) We have prepared immobilized olefins as models for the cross metathesis using different olefin partners in the presence of second generation Grubbs and Hoveyda-Grubbs precatalysts. We have demonstrated that solid-phase cross metathesis is strongly dependent on the degree of homodimerization of the non-immobilized olefin and the reactivity of such a homodimer. As in the homogeneous phase, the Hoveyda-Grubbs precatalyst was better for immobilized α,β-unsaturated carbonyl compounds.
- Poeylaut-Palena, Andres A.,Testero, Sebastian A.,Mata, Ernesto G.
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p. 2024 - 2027
(2008/09/19)
-
- The first sequential reaction promoted by manganese: Complete stereoselective synthesis of (E)-α,β-unsaturated esters from 2,2-dichloroesters and aldehydes
-
(Chemical Equation Presented) α,β-Unsaturated esters were obtained with complete control of stereoselectivity utilizing a sequential reaction of dichloroesters with a variety of aldehydes, promoted by active manganese. This methodology is generally applicable, and the C-C double bond can be di- or trisubstituted. A mechanism based on a successive aldol-type reaction/β-elimination is proposed to explain these results.
- Concellon, Jose M.,Rodriguez-Solla, Humberto,Diaz, Pamela,Llavona, Ricardo
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p. 4396 - 4400
(2008/02/05)
-
- PYRROLIDINE DERIVATIVE OR SALT THEREOF
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[PROBLEMS] To provide a compound which can be used for the treatment of a disease associated with a calcium-sensing receptor (CaSR), particularly hyperparathyroidism. [MEANS FOR SOLVING PROBLEMS] It is found that a novel pyrrolidine derivative having an aminomethyl group substituted by an arylaklyl group or the like or a salt thereof has an excellent CaSR agonistic modulation effect and also has an excellent selectivity in the inhibition of CYP2D6 which may cause a drug-drug interaction. Thus, the novel pyrrolidine derivative is useful as a therapeutic agent for a disease associated with CaSR (e.g., hyperparathyroidism, renal osteodystrophy and hypercalcemia).
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-
Page/Page column 62
(2008/06/13)
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- Cryptophycin compounds
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The present invention provides cryptophycin compounds of Formula I that are useful in the treatment of neoplasms.
- -
-
Page/Page column 47; 53
(2010/02/05)
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- A highly stereospecific synthesis of (E)-α,β-unsaturated esters
-
CrCl2-induced olefination of aldehydes using methyl dichloroacetate exclusively generates (E)-α,β-unsaturated esters in excellent yields. The intermediate α-chloro-β-hydroxy adducts could also be isolated in good yields under conditions of limited reagent.
- Barma, Deb K.,Kundu, Asish,Bandyopadhyay, Anish,Kundu, Abhijit,Sangras, Bhavani,Briot, Anne,Mioskowski, Charles,Falck
-
p. 5917 - 5920
(2007/10/03)
-
- Synthesis of optically active β-alkyl aspartate via [3,3] sigmatropic rearrangement of α-acyloxytrialkylsilane
-
The synthesis of four types of optically active β-carbon-substituted analogs of threo-β-hydroxy aspartate (THA) and a β-carbon-substituted analog of threo-β-benzyloxy aspartate (TBOA), which are potent blockers of excitatory amino acid transporters in the
- Sakaguchi, Kazuhiko,Yamamoto, Masahiro,Kawamoto, Tetsuo,Yamada, Takeshi,Shinada, Tetsuro,Shimamoto, Keiko,Ohfune, Yasufumi
-
p. 5869 - 5872
(2007/10/03)
-
- Pharmaceutical compounds
-
The invention provides novel cryptophycin compounds which can be useful for disrupting the microtubulin system, as antineoplastic agents, antifungal, and for the treatment of cancer. The invention further provides a formulation for administering the novel cryptophycin compounds.
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-
-
- Syntheses of α,β-unsaturated carbonyl compounds from the reactions of monosubstituted ozonides with stable phosphonium ylides
-
Ozonides derived from terminal alkenes reacted with 1.3 mol equiv. of stable phosphonium ylides to give (E)-αβ-unsaturated carbonyl compounds in good to excellent yields. No reducing agent is needed in the reaction. However, alkoxyalkyl-substituted ozonides afforded a mixture of (Z)- and (E)-αβ-unsaturated carbonyl compounds under similar condition. The E/Z isomeric ratio is affected by the position of the heteroatom in the substituent of the ozonides. The possible mechanism of this reaction will be discussed. (C) 2000 Elsevier Science Ltd.
- Hon, Yung-Son,Lu, Ling,Chang, Rong-Chi,Lin, Sheng-Wun,Sun, Pei-Pei,Lee, Chia-Fu
-
p. 9269 - 9279
(2007/10/03)
-
- The reaction of triphenylphosphonium or triphenylarsonium salts with aldehyde: Effect of the counteranion on their reactivity
-
Some acetonyltriphenylphosphonium, methoxycarbonylmethyltriphenylphosphonium salts and their triphenylarsonium analogues could undergo Wittig reaction with aldehyde in good yields. Their reactivity was counteranion-dependent and was arranged in the following order: p-TsO-, Br-3CO2/-2CO2/-2/-, HCO2/-, MeCO2/-. The proton-coupled 13C NMR splitting patterns of the α-methylene groups provided a valuable information to predict their reactivity with aldehyde. Only those onium salts without C-H coupling could undergo Wittig reaction. (C) 2000 Elsevier Science Ltd.
- Hon, Yung-Son,Lee, Chia-Fu
-
p. 7893 - 7902
(2007/10/03)
-
- Isoxazoline and isoxazole fibrinogen receptor antagonists
-
This invention relates to novel isoxazolines and isoxazoles which are useful as antagonists of the platelet glycoprotein IIb/IIIa fibrinogen receptor complex or the vitronectin receptor, to pharmaceutical compositions containing such compounds, processes for preparing such compounds, and to methods of using these compounds, alone or in combination with other therapeutic agents, for the inhibition of platelet aggregation, as thrombolytics, and/or for the treatment of thromboembolic disorders.
- -
-
-
- New reaction mode of the Horner-Wadsworth-Emmons reaction using Sn(OSO2CF3)2 and N-ethylpiperidine
-
Excellent Z or E selectivity is observed in the Horner-Wadsworth-Emmons reactions of methyl bis(trifluoroethyl)phosphonoacetate 2 with aryl alkyl ketones 3a-d or aldehydes 3f,g using Sn(OSO2CF3)2 in the presence of N-ethylpiperidine, which should have a different reaction mode to those using sodium hydride.
- Sano, Shigeki,Yokoyama, Kenji,Fukushima, Mari,Yagi, Tetsuo,Nagao, Yoshimitsu
-
p. 559 - 560
(2007/10/03)
-
- An Extremely Efficient Way to Prepare Conjugated Carbonyl Compounds from Terminal Alkenes via the Reactions of Ozonides, Triethylamine and Stable Phosphorus Ylides
-
Ozonides derived from mono- and 1,1-di-substituted olefins reacted with triethylamine in the presence of nucleophiles, such as phosphorus ylide or phosphonoacetate to give conjugated carbonyl compounds almost instantaneously in excellent yields.These transformations were accelerated by the by-product (i.e. thermal energy and ammonium formate) generated in the reaction.
- Hon, Yung-Son,Lu, Ling
-
p. 7937 - 7942
(2007/10/02)
-
- The invention of radical reactions. Part XXXIV. Homologation of carboxylic acids to α-keto carboxylic acids by Barton-ester based radical chain chemistry
-
Carboxylic acids can be transformed into the homologous α-keto acids by Barton-ester based radical chemistry. The method was especially successful when ethyl α-trifluoroacetoxy acrylate was used as a radical trap.
- Barton, Derek H. R.,Chern, Ching-Yuh,Jaszberenyi, Joseph Cs.
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p. 1867 - 1886
(2007/10/02)
-
- Total synthesis of cryptophycins. Revision of the structures of cryptophycins A and C
-
The convergent total synthesis of cryptophycins C and D is described. It has been shown that in both natural products the absolute configuration of the α-amino acid corresponds to the D-series. The structural assignment for cryptophycin C has been correct
- Barrow, Russell A.,Hemscheidt, Thomas,Liang, Jian,Paik, Seunguk,Moore, Richard E.,Tius, Marcus A.
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p. 2479 - 2490
(2007/10/02)
-
- Efficient Oxidation of Phenyl Groups to Carboxylic Acids with Ruthenium Tetraoxide. A Simple Synthesis of (R)-γ-Caprolactone, the Pheromone of Trogoderma granarium
-
The oxidation of aromatic rings to carboxylic acids with ruthenium tetraoxide is shown to be a very efficient and simple reaction using periodic acid as the stoichiometric oxidant in a biphasic solvent system (CCl4, CH3CN, H2O).The reaction can be very sensitive to the nature of the ring substituents when more than one aromatic ring is present.The procedure is compatible with other functional groups except for those that are quite acid sensitive.A simple synthesis of (R)-γ-caprolactone employs Sharpless asymmetric epoxidation and the presented oxidation procedure as key steps.
- Nunez, M. Teresa,Martin, Victor S.
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p. 1928 - 1932
(2007/10/02)
-
- Substituted aryl ureas as high potency sweeteners
-
Substituted ureas and thioureas are disclosed for use as high potency sweeteners.
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-
-
- Enantioselective Hydrolysis of Dialkyl 3-Monosubstituted Glutarates with Pig Liver Esterase: Structure-Optical Purity Relationships
-
Dialkyl 3-monosubstituted glutarates are subjected to hydrolysis with pig liver esterase to afford the corresponding chiral half-esters.Synnthetically useful half-esters of higher optical purity are obtained from the prochiral substrates of more hydrophob
- Nakada, Masahisa,Kobayashi, Susumu,Ohno, Masaji,Iwasaki, Shigeo,Okuda, Shigenobu
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p. 3951 - 3954
(2007/10/02)
-