- Base-Mediated Radical Borylation of Alkyl Sulfones
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A practical and direct method was developed for the production of versatile alkyl boronate esters via transition metal-free borylation of primary and secondary alkyl sulfones. The key to the success of the strategy is the use of bis(neopentyl glycolato) diboron (B2neop2), with a stoichiometric amount of base as a promoter. The practicality and industrial potential of this protocol are highlighted by its wide functional group tolerance, the late-stage modification of complex compounds, no need for further transesterification, and operational simplicity. Radical clock, radical trap experiments, and EPR studies were conducted which show that the borylation process involves radical intermediates.
- Huang, Mingming,Hu, Jiefeng,Krummenacher, Ivo,Friedrich, Alexandra,Braunschweig, Holger,Westcott, Stephen A.,Radius, Udo,Marder, Todd B.
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supporting information
(2021/12/02)
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- Nature of the intermediates in gold(I)-catalyzed cyclizations of 1,5-enynes
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The carbene or carbocationic nature of the intermediates in the gold-catalyzed cycloisomerization of 1,5-enynes can be revealed, depending on the ligands on the gold catalysts. Gold complexes with highly electron-donating ligands promote reactions that proceed via intermediates with carbene-like character, leading to products with a bicyclo[3.1.0]hexene skeleton. The intermediate cyclopropyl endo-gold carbenes formed in this cyclization have been trapped, for the first time, to give biscyclopropane derivatives in a reaction that proceeds in a concerted fashion, according to DFT calculations.
- Lopez-Carrillo, Veronica,Huguet, Nuria,Mosquera, Ungeles,Echavarren, Antonio M.
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supporting information; experimental part
p. 10972 - 10978
(2011/10/18)
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- An expeditious entry to benzylic and allylic sulfones through byproduct-catalyzed reaction of alcohols with sulfinyl chlorides
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(Chemical Equation Presented) In the absence of external catalysts and additives, a broad range of benzylic and allylic alcohols react with various sulfinyl chlorides to afford structurally diversified benzylic and allylic sulfones in moderate to excellen
- Li, Hai-Hua,Dong, De-Jun,Jin, Yin-Huan,Tian, Shi-Kai
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supporting information; experimental part
p. 9501 - 9504
(2010/03/04)
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- Catalyst-free alkylation of sulfinic acids with sulfonamides via sp 3 C-N bond cleavage at room temperature
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An unprecedented catalyst-free alkylation of sulfinic acids with sulfonamides has been developed via sp3 C-N bond cleavage at room temperature. In the absence of external catalysts and additives, a wide variety of N-benzylic and N-allylic sulfonamides couple with sulfinic acids to give structurally diversified sulfones in moderate to excellent yields. Furthermore, the reaction of N-(2-acyl)allylic sulfonamides with sulfinic acids provides a convenient access to trisubstituted allyl sulfones with exclusive Z selectivity.
- Liu, Cong-Rong,Li, Man-Bo,Cheng, Dao-Juan,Yang, Cui-Feng,Tian, Shi-Kai
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supporting information; scheme or table
p. 2543 - 2545
(2009/10/10)
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- π-Allylic sulfonylation in water with amphiphilic resin-supported palladium-phosphine complexes
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π-Allylic substitution of allyl esters with sodium arylsul-finate was performed with an amphiphilic polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported phosphine-palladium complex in water as a single reaction medium under heterogeneous conditions to give allyl sulfones in good to high yields. Catalytic asymmetric allylic substitution of cycloalkenyl esters also took place in water using a PS-PEG resin-supported chiral imidazo-indolephosphine- palladium complex to give cycloalkenyl sulfones with up to 81% ee.
- Uozumi, Yasuhiro,Suzuka, Toshimasa
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experimental part
p. 1960 - 1964
(2009/04/04)
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- ARYL CARBOXYLIC ACID CYCLOHEXYL AMIDE DERIVATIVES
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A compound of formula (I) or a pharmaceutically acceptable salt or prodrug ester thereof: (I) wherein the variants R and X are defined in the specification.
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Page/Page column 13
(2008/12/08)
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- Ionic liquid/water as a recyclable medium for Tsuji-Trost reaction assisted by microwave
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An efficient microwave protocol is described for allylic substitution with various carbon and heteronucleophiles catalyzed by Pd(OAc)2/TPPTS in an [EMIm]BF4/H2O medium. The ionic liquid/water containing catalyst system can be recycled eight times without loss of activity.
- Liao, Meng-Chun,Duan, Xin-Hua,Liang, Yong-Min
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p. 3469 - 3472
(2007/10/03)
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- Towards asymmetric catalysis in the major groove of 1,1′-binaphthalenes
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Four new diphosphane ligands, (R)-4, (R)-5, (S)-6, and (R)-7 (Schemes 3, 4, 6, and 7), featuring metal-coordination sites located in the major groove of chiral 1,1′-binaphthalene clefts, were prepared in enantiomerically pure form. The performance of this new class of ligands was tested in enantioselective, Pd-catalyzed allylic alkylation reactions with acyclic and cyclic methyl carbonates 28-30 as substrates under various reaction conditions (Schemes 8 and 9). Using sodium phenyl sulfinate as a nucleophile, the reactivity of the catalysts formed with the new ligands and suitable palladium precursors was found satisfactory (> 90%); however, the ee values were in all cases poor (31P-NMR-Spectroscopic investigations revealed the formation of multiple-catalyst species in solution (Fig. 2), and molecular modeling suggested a lack of embedding of the coordinated substrate in a 'chiral pocket' (Fig. 3), which probably accounts for the observed low level of enantioselectivity.
- Lustenberger, Philipp,Diederich, Francois
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p. 2865 - 2883
(2007/10/03)
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- Cathodic behaviour of 1-cycloalken-1-yl phenyl sulfones. I. Competition among dimerization, cleavage, isomerization and oligomerization processes in aprotic media
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1-Cycloalken-1-yl phenyl sulfones 1a and 1b have been studied electrochemically in aprotic media (N,N-dimethylformamide, dimethyl sulfoxide, or acetonitrile containing tetraalkylammonium salts) at a mercury electrode. Their behaviour has been compared with that of 2-norbornen-2-yl phenyl sulfone 1c. The expected cleavage reaction is accompanied by a concomitant isomerization process into allyl sulfones that is triggered by electrogenerated bases. A quantitative determination of the product distribution during controlled-potential electrolyses suggests the formation of dimers and oligomeric species, arising through a Michael addition of the sulfone anions to the activated double bond of these sulfones.
- Prigent, Sylvie,Cauliez, Pascal,Simonet, Jacques,Peters, Dennis G.
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p. 892 - 900
(2007/10/03)
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- Phenylsulfonyl as a β participating group
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The phenylsulfonyl group (PhSQ2) has been examined for its β effect properties. The stereochemical relationship was varied between phenylsulfonyl and a nucleophilic leaving group (nucleofuge) separated by two carbons. Mechanisms were distinguished through solvent effects on rates and products. When the stereochemistry between the two groups was gauche, the only effect of phenylsulfonyl was strong inductive retardation in a mechanism involving solvent participation. With the antiperiplanar stereochemistry, however, the mechanism clearly changed to carbocation formation with a small kinetic acceleration. Thus, phenylsulfonyl is a weak β effect substituent. This remarkable property for a strongly electron-withdrawing group occurs most likely through hyperconjugation or possibly through anchimeric assistance.
- Lambert, Joseph B.,Beadle, Beth M.,Kuang, Kuiyang
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p. 9241 - 9246
(2007/10/03)
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- Phosphazene base P2-Et mediated isomerization of vinyl sulfones to allyl sulfones
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Treatment of vinyl sulfones with 0.1-0.2 eq of Phosphazene base, P2-Et in THF at 25°C affords the corresponding allyl sulfones in high yield. P2-Et has shown clear superiority to both DBU and KO-t-Bu in these reactions.
- Jin, Zhendong,Kim, Seong Heon,Fuchs
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p. 5247 - 5248
(2007/10/03)
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- Synthesis of 2-(Trimethylsilyl)ethyl Benzenesulfenate and Benzeneselenenate and Their Reaction with Some Electrophiles in the Presence of Tetrabutylammonium Fluoride
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2-(Trimethylsilyl)ethyl benzenesulfenate was allowed to react with several halides in the presence of tetrabutylammonium fluoride (TBAF) to afford the corresponding phenyl sulfoxides as the main product.In the reaction of 2-(trimethylsilyl)ethyl benzeneselenenate and several halides with TBAF, the corresponding alcohols were obtained as the main product.
- Oida, Tatsuo,Ohnishi, Atsushi,Shimamaki, Toshiharu,Hayashi, Yoshiyuki,Tanimoto, Shigeo
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p. 702 - 704
(2007/10/02)
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- Rearrangement of Some Allylic Sulphinate Esters to Allylic Sulphones. Ion-pair and Sigmatropic Shift Mechanisms
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The mechanism of rearrangement of a number of allylic sulphinate esters to the corresponding allylic sulphones on heating in formamide has been investigated as a function of substrate structure.Simple systems such as crotyl and α-methylallyl-sulphinate ap
- Knight, Derek J.,Whitham, Gordon H.,Williams, Jonathan G.
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p. 2149 - 2152
(2007/10/02)
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- Nickel- and Palladium-Catalyzed Additions of Nucleophiles to Cyclic 1,3-Dienes
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Carbon nucleophiles have been found to add smoothly to 1,3-cyclohexadiene using either a preformed nickel-ligand complex or Ni(0) prepared by in situ reduction of Ni(II) in the presence of a ligand to give 1,2- and 1,4-addition products.Analogous adducts were also obtained from 1,3-cyclopentadiene and 1,3-cyclooctadiene, but the yields were considerably lower.Attempts to add benzenesufinic acid to 1,3-cyclohexadiene using Ni(0) were unsuccessful; this reaction was instead found to be catalyzed by Pd(0)-phosphite complexes.
- Andell, Ove S.,Baeckvall, Jan-E.,Moberg, Christina
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p. 184 - 189
(2007/10/02)
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- Palladium-Catalyzed Substitutions of Allylic Nitro Compounds. Regiochemistry
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Primary, secondary, and tertiary allylic nitro compounds underwent Pd(0)-catalyzed allylic substitution by stabilized carboanions, secondary amines, and benzenesulfinate ion (PhSO2-). α,β-disubstituted α-nitro olefins also behaved as allylic nitro compounds, via base-catalyzed vinyl -> allyl rearrangement, and underwent allylic substitution by secondary amines and PhSO2-.The regiochemistry of these substitutions was dependent on the structure of the allylic nitro compound amd on the steric bulk of the nucleophile.Generally, substitution occurred at the lesshindered or least substituted site.In some cases added or generated NaNO2 affected the regioselectivity of the allylic substitution of allylic nitro compounds and some allylic acetates by PhSO2-.Under these conditions, the more sterically hindered allylic sulfones were formed.
- Tamura, Rui,Kai, Yoshiki,Kakihana, Masato,Hayashi, Koji,Tsuji, Masanori,et al.
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p. 4375 - 4385
(2007/10/02)
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- PALLADIUM CATALYZED SYNTHESIS OF ALLYLIC SULFONES. UTILIZATION OF α-NITRO OLEFINS AS ALLYLIC NITRO COMPOUNDS
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α-Nitro olefins reacted with sodium benzenesulfinate in the presence of tertiary amine and palladium(0) catalyst to afford allylic sulfones.The competition experiment showed that relative rate of the sulfonylation of an α-nitro olefin to that of the corre
- Tamura, Rui,Hayashi, Koji,Kakihana, Masato,Tsuji, Masanori,Oda, Daihei
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p. 229 - 232
(2007/10/02)
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- ELIMINATION AND ADDITION REACTIONS. PART 39. VARIATION OF NUCLEOFUGALITY WITH TRANSITION STATE STRUCTURE-1,3- AND 1,2-ELIMINATIONS FROM CARBANIONS COMPARED.
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Phenylsulphonyl-activated 1,3-eliminations have been investigated with the objective of determining nucleofugalities of six leaving groups.In cyclohexane-1,3-diyl and propane-1,3-diyl system unactivated 1,2-elimination of 'poor' leaving groups occurs faster than 1,3-elimination.In 2,2-dimethylpropane-1,3-diyl substrates, however, quantitative 1,3-eliminations occur and the nucleofugalities of Br, Cl, OTs, PhSO2, PhS, PhO, have been determined.In a linear free energy relationship extending over 15 pKa units and 12 rank units, an excellent correlation of nucleofugality with the pKa of the conjugate acid of the leaving group is found.It is concluded from the comparison with 1,2-eliminations previously studied that 1,3-elimination involves considerable leaving group separation and ring formation in the transition state.With bromide as leaving group, the 2,2-dimethylpropane-1,3-diyl system is 1000 times more reactive in cyclopropane formation than the propane-1,3-diyl system; this is the first quantitation of the Thorpe-Ingold effect in homocyclic ring formation.With chloride and tosylate leaving groups, smaller accelerations are observed.
- Issari, Bahram,Stirling, Charles J. M.
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p. 1043 - 1052
(2007/10/02)
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