594-34-3Relevant articles and documents
REACTION OF ACETYLENIC AND VINYLIC ORGANOLITHIUM REAGENTS WITH TRIETHOXYCARBENIUM TETRAFLUOROBORATE: PREPARATION OF α-ACETYLENIC AND α-ETHYLENIC TRIETHYL ORTHOCARBOXYLATES
Picotin, G.,Miginiac, Ph.
, p. 249 - 254 (1987)
Acetylenic and vinylic liyhium derivatives react with triethoxycarbenium tetrafluoroborate to give α-unsaturated triethyl orthocarboxylates.
Oxidative bromination of alkenes mediated with nitrite in ionic liquids
Kuznetsova, Lidia I.,Kuznetsova, Nina I.,Zudin, Vladimir N.,Utkin, Viktor A.,Trebushat, Dmitry V.,Fedotov, Martin A.,Larina, Tatyana V.
, p. 1499 - 1506,8 (2014/11/08)
The oxidative bromination of C2-C8 alkenes with HBr-NaNO2-O2 in solutions of BMImBr, HMImBr or BMImBF 4 containing 16-28 wt% H2O was studied using volumetric method, GC-MS analysis, 14N NMR and UV-VIS spectroscopy. The optimal conditions to conduct the reaction at high selectivity for 1,2-dibromoalkanes in BMImBr were determined. The composition of ionic liquid affects the catalytic performance. Although in BMImBF4 the reaction runs with equal rate as in bromide ionic liquid, the fraction of bromohydrin in the reaction products increases to 20 %. Generated from NaNO2, NOx operated as a catalyst in the oxidation of Br- and was oxidized to catalytically inert NO3 - anions when complete conversion of HBr was attained. Graphical Abstract: Oxidative bromination of alkenes [Figure not available: see fulltext.]
The reaction of bis(trifluoromethyl)amino-oxyl with t-butyl bromide, t-butyl chloride, 2,2-dichloropropane, 2-chloro-2-phenylpropane and t-butyl acetate
Connelly, Gregory D.,Tipping, Anthony E.
, p. 83 - 92 (2007/10/02)
Reaction of the oxyl (CF3)2NO(.) (1) with t-butyl bromide (c. 2:1 molar ratio) at room temperature results in initial hydrogen abstraction to give the hydroxylamine (CF3)2NOH (3) and the radical (.)CH2CMe2Br (17) which (i) couples with oxyl 1 to afford the compound (CF3)2NOCH2CMe2Br (6) (33.5percent) and (ii) eliminates a bromine atom to give the alkene CH2=CMe2.Addition of oxyl 1 and bromine to the alkene affords the adducts (CF3)2NOCH2CMe2ON(CF3)2 (4) (10percent) and CH2BrCMe2Br (8) (26.5percent), respectively, while allylic hydrogen abstraction from the alkene leads to the compounds 2CMeON(CF3)2 (5) (10percent) and (CF3)2NOCH2CMeCH2Br (7) (15.5percent).Reaction with t-butyl chloride is more complex and gives a number of unidentified products together with the compounds 4 (37percent), 5 (8percent) and (CF3)2NOCH2CMeCH2Cl (9) (3.5percent) formed by an analogous reaction pathway, although the large amount of hydrogen chloride (61percent) isolated indicates that hydrogen abstraction by chlorine atoms competes with abstraction by oxyl 1.With 2,2-dichloropropane, reaction with the oxyl 1 is slow (even at 70-80 deg C) and gives mainly hydrogen chloride, hydroxylamine 3 (32percent), the substitution product (CF3)2NOCH2CCl2CH3 (10) (42percent) and the 2:1 adduct of oxyl 1 and the alkene CH2=CMeCl, i.e. (CF3)2NOCH2CMeClON(CF3)2 (11) (24percent).In contrast, reaction involving 2-chloro-2-phenylpropane is facile at room temperature and affords hydrogen chloride (97.5percent), hydroxylamine 3 (12.5percent) and the 2:1 adduct (CF3)2NOCH2CMePhON(CF3)2 (12) (78percent) of oxyl 1 and the alkene CH2=CMePh.Treatment of t-butyl acetate with oxyl 1 gives hydroxylamine 3 (49percent), the oxadiazapentane (CF3)2NON(CF3)2 (2) (9percent) and the compounds (CF3)2NOCH2CMe2OAc (14) (36percent), 2CHCMe2OAc (15) (15percent) and (CF3)2NO2CCMe2OAc (16) (40percent) formed via successive oxyl 1 attack on a methyl group.In these reactions, compounds arising via a 1,2-shift of bromine, chlorine or acetate were not detected in the products.
Solvent Effects on the Rate of Heterolysis of t-Butyl Chloride, Bromide, Iodide, and 2,4-Dinitrophenolate
Mitsuhashi, Tsutomu,Hirota, Hiroshi,Yamamoto, Gaku
, p. 824 - 830 (2007/10/02)
Rates of heterolytic decompositions of t-butyl chloride, bromide, iodide, and 2,4-dinitrophenolate have been measured by an NMR method in eight deuterated or undeuterated polar solvents; methanol-d4, ethanol-d6, dimethyl-d6 sulfoxide, N,N-dimethylformamide-d7, acetonitrile-d3, pyridine, nitrobenzene, and acetone-d6.The observed solvent effect is discussed on the basis of cation and anion solvation.With t-butyl halides, the anion solvation due to hydrogen bonding by protic solvents drastically decreases on increasing the radius of halide ions, and thus the differential solvation transferred from anion-solvating methanol to cation-solvating dimethyl sulfoxide is dramatically reversed on going from the chloride to the iodide (kMe2SO-d6/kmethanol-d4 at 60 deg C: t-BuCl, 5E-2; t-BuBr, 6E-1; t-BuI, 7).The 2,4-dinitrophenolate behaves like the iodide.Complicated products are obtained in the decomposition of t-butyl bromide in dimethyl sulfoxide; however, a mechanism involving a bimolecular decomposition process of the bromide is ruled out.During the decomposition od t-butyl iodide in dimethyl sulfoxide, an intermediate salt t-butoxydimethylsulfonium iodide has been detected.The salt decomposes to isobutene, but the process is much slower than the heterolytic decomposition of t-butyl iodide itself at ambient temperature.
Synthesis of the stereoisomers of a novel antibacterial agent and interpretation of their relative activities in terms of a theoretical model of the penicillin receptor
Wolfe,Zhang,Johnston,Kim
, p. 1066 - 1075 (2007/10/02)
2,2-Dimethyl-3-(2'-hydroxypropyl)-5-carboxy-Δ3-1,4-thiazine (1) is a designed antibacterial agent. Based on an analysis of how penicillin complexes to and reacts with a model of a penicillin-binding protein, 1 contains a functional group (C=N) that can react with a serine hydroxyl group of the receptor according to the putative reaction Enz-OH + C=N → Enz-O-C-NH. Compound 1 also contains additional substituents that are designed to position the O-H and C=N groups relative to one another in the enzyme-substrate complex in a geometry that attempts to reproduce the optimum geometry of approach of two such reactants. A most important assumption is that this optimum geometry can be computed ab initio. In a first preparation of 1, (±)-5-methyl-4-hexene-2-ol (2) was converted to the lithium salt of (±)-2-mercapto-2-methyl-5-tert-butyldimethylsiloxy-3-hexanone (7), which was condensed with the N-tert-butoxycarbonyl-D- and L-serine-β-lactones (3). The synthesis was completed by deprotection with formic acid and cyclization in water. The R and S enantiomers of 2 have now been obtained, and the absolute configuration of the alcohol established, by reaction of the R- and S-propylene oxides with an organometallic reagent prepared from β,β-dimethylvinyl bromide. The R alcohol has also been secured by lipase-catalyzed transesterification with trifluoroethyl butyrate, and chemical hydrolysis of the trifluoroethyl ester. The R and S enantiomers of 2 were converted to the R and S enantiomers of 7, and these were condensed with the R and S enantiomers of 3 to yield each of the stereoisomers of the chemically unstable 1 in ca. 95% optically pure form. Antibacterial activity resides in the 5S,8R and 5S,8R isomers. These findings are shown to be consistent with the theoretical model. It is hoped that the stability of the lead structure 1 can be improved, to allow binding experiments with penicillin recognizing enzymes to proceed. 2,2-Dimethyl-3-(2′-hydroxypropyl)-5-carboxy- Δ3-1,4-thiazine (1) is a designed antibacterial agent. Based on an analysis of how penicillin complexes to and reacts with a model of a penicillin-binding protein, 1 contains a functional group (C = N) that can react with a serine hydroxyl group of the receptor according to the putative reaction Enz-OH + C = N → Enz-O-C-NH. Compound 1 also contains additional substituents that are designed to position the O-H and C = N groups relative to one another in the enzyme-substrate complex in a geometry that attempts to reproduce the optimum geometry of approach of two such reactants. A most important assumption is that this optimum geometry can be computed ab initio. In a first preparation of 1, (±)-5-methyl-4-hexene-2-ol (2) was converted to the lithium salt of (±)-2-mercapto-2-methyl-5-tert-butyldimethylsiloxy-3-hex anone (7), which was condensed with the N-tert-butoxycarbonyl-D- and L-serine-β-lactones (3). The synthesis was completed by deprotection with formic acid and cyclization in water. The R and S enantiomers of 2 have now been obtained, and the absolute configuration of the alcohol established, by reaction of the R- and S-propylene oxides with an organometallic reagent prepared from β,β-dimethylvinyl bromide. The R alcohol has also been secured by lipase-catalyzed transesterification with trifluoroethyl butyrate, and chemical hydrolysis of the trifluoroethyl ester. The R and S enantiomers of 2 were converted to the R and S enantiomers of 7, and these were condensed with the R and S enantiomers of 3 to yield each of the stereoisomers of the chemically unstable 1 in ca. 95% optically pure form. Antibacterial activity resides in the 5S,8R and 5S,8S isomers. These findings are shown to be consistent with the theoretical model. It is hoped that the stability of the lead structure 1 can be improved, to allow binding experiments with penicillin recognizing enzymes to proceed.
SYNTHESIS, STRUCTURE, AND CHEMICAL PROPERTIES OF TRIMETHYLSILYL DERIVATIVES OF THIOLACTAMS
Sergeev, V. N.,Artamkin, S. A.,Pestunovich, S. V.,Albanov, A. I.,Voronkov, M. G.,Baukov, Yu. I.
, p. 1490 - 1497 (2007/10/02)
Trimethylsilyl derivatives of five-, six-, and seven-membered thiolactams with an N-silyl structure were synthesized for the first time.Their alkylation with primary alkyl halides under comparatively mild conditions occurs at the sulfur atom; the reaction with secondary alkyl halides is accompanied by hydrogen halide elimination, and this becomes the only reaction pathway with tertiary halides.The preparative acylation of N-trimethylsilylthiolactams yields N-acyl derivatives; the intermediate formation of S-acylation products was established by means of low-temperature NMR monitoring.
THE 2,2'-SPIROBICHROMAN - 1,1'-SPIROBIINDAN-4,4'-DIOL REARRANGEMENT. II
Tanaka, Tsuguo,Miyaguchi, Masao,Mochisuki, Rosalina K.,Tanaka, Senichiro,Okamoto, Masaya,et al.
, p. 463 - 484 (2007/10/02)
The reaction of 2,2'-spirobichroman derivatives with either hydrobromic acid in the acetic acid solution or aluminum chloride in the chlorobenzene solution yielded 1,1'-spirobiindan-4,4'-diol analogues.The reaction is peculiar as compared with the reaction of alkyl aryl ethers with the same reagents in the same media.
Bromochlorination of Alkenes with Dichlorobromate (1-) ion. IV. Regiochemistry of Bromochlorinations of Alkenes with Molecular Bromine Chloride and Dichlorobromate (1-) Ion
Negoro, Takeshi,Ikeda, Yoshitsugu
, p. 2547 - 2552 (2007/10/02)
The regioselectivity of the addition of molecular bromine chloride to alkenes is dependent on both the steric and electronic effects of the alkyl substituent.In contrast, the regioselectivity of the addition of dichlorobromate (1-) ion to alkenes is controlled mainly by the steric effect of the substituent.
Imidyl Radicals. The Chemistries of 1,8-Naphthalenedicarboximidyl and Phthalimidyl Radicals
Day, J. C.,Govindaraj, N.,McBain, D. S.,Skell, P. S.,Tanko, J. M.
, p. 4959 - 4963 (2007/10/02)
The chemistries of 1,8-naphthalenedicarboximidyl (N.) and phthalimidyl (P.) radicals are described.Hydrogen abstractions from alkanes and additions to olefins and benzene proceed in high yield.The low cost of phthalimide, coupled with the absence of a parasitic ring-opening reaction for P., makes N-bromophthalimide an economical reagent for low-selectivity brominations.The chemistry of N. resembles that of other imidyl radicals (succinimidyl, glutarimidyl) with respect to selectivities.Conversely, P. is somewhat of a maverick among imidyl radicals, being slightly more selective in its reactions, but still 102-103 less selective than Br..
