An extensive study of bromination of cis,trans,trans-1,5,9-cyclododecatriene: product structures and conformations (original) (raw)
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The Journal of Organic Chemistry, 2007
Cartesian coordinates of the optimized structure and energy values for 5 S Cartesian coordinates of the optimized structure and energy values for 22 S Cartesian coordinates of the optimized structure and energy values for 19 S Cartesian coordinates of the optimized structure and energy values for 20 S Cartesian coordinates of the optimized structure and energy values for 31 S Cartesian coordinates of the optimized structure and energy values for 29 S Cartesian coordinates of the optimized structure and energy values for 32 S Cartesian coordinates of the optimized structure and energy values for 30 S Cartesian coordinates of the optimized structure and energy values for TS29A S Cartesian coordinates of the optimized structure and energy values for TS29B S Cartesian coordinates of the optimized structure and energy values for TS31A S Cartesian coordinates of the optimized structure and energy values for TS31B S Cartesian coordinates of the optimized structure and energy values for TS37A S Cartesian coordinates of the optimized structure and energy values for TS37B S Cartesian coordinates of the optimized structure and energy values for TS38A S Cartesian coordinates of the optimized structure and energy values for TS38B S Cartesian coordinates of the optimized structure and energy values for 29B S Cartesian coordinates of the optimized structure and energy values for 31A S Cartesian coordinates of the optimized structure and energy values for 37B S Cartesian coordinates of the optimized structure and energy values for 38A S Experimental Section General: Melting points are uncorrected. Infrared spectra were obtained from solution in 0.1 mm cells or KBr pellets on a regular instrument. The 1 H and 13 C NMR spectra were recorded on 400 (100) and 200 (50) MHz spectrometers. Apparent splitting is given in all cases. Column chromatography was performed on silica gel (60-mesh, Merck) TLC was carried out on Merck 0.2 mm silica gel 60 F 254 analytical aluminum plates. All substances reported in this paper are in their racemic form.
cis-Bromination of Encapsulated Alkenes
Angewandte Chemie International Edition, 2003
Metalated container molecules are currently attracting much interest, since their properties are often different from those of their constituent components. [1-3] Several groups have already reported that such assemblies show a higher chemical reactivity than their unmodified analogues, [4-6] but so far it is unclear, whether they are also applicable in stereoselective transformations. [7, 8] This led us to study the bromination of encapsulated alkene ligands in complexes of the type A (Scheme 1); we hoped that the binding pocket would exert an
Magnetic Resonance in Chemistry, 2005
The electrophilic addition of bromine to dibromohomobenzonorbornadiene derivatives at −45 ± 5 • C led to the formation of the rearranged and non-rearranged tetrabromides in a ratio of 6 : 4. However, high-temperature bromination of the same system in CCl 4 at 77 • C produced only non-rearranged products. The formation mechanism of the isomers and the role of the substituent on the rearrangement is discussed. The structure elucidation of the isomeric tetrabromides was achieved from NMR spectral data. The agreement between the calculated dihedral angles and the measured coupling constants is especially excellent. The g-gauche effect is discussed.
ChemInform Abstract: Use of Bromine and Bromo-Organic Compounds in Organic Synthesis
ChemInform, 2016
Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ringopening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.
High temperature bromination VI: Bromination of benzobarrelene
Tetrahedron, 1994
Alslrrer: The electrophilic addition of bromine to benzobarrelene in chloroform at 10° C followed by mpeated chnnnatography combined with fractional crystallization allowed us to isoktte ten products 12-21 StnWual determination of these compounds revealed that the banelene skeleton was rearranged completely. 18-21 are alcohol compounds which arise from hydrolysis of 12, 13, 14, andl5, mspectively. High tempemture bmmination of benzobarrelene in decalin at I50 Oc followed by qxated chmm&gmphy combined with fractional crystallization gave us 18 products. Nonrevranged products 24,25, and 26 have been isolated in 50% yield. All compounds have been characterized properly, especially by 200 MHz lH NMR and 50 M?lz 13C NMR spectra. Furthermore, it has been concluded that hi8h tempetatme bMmi&at of bicyclic systems gives more non-nxmutged products. If the molecule ismaestrained,thetendencytoreanange~a9inthewseofbenz~~e.
Beilstein Journal of Organic Chemistry
Previously we reported on the bromination of endo-7-bromonorbornene at different temperatures yielding mixtures of addition products. The structural elucidations of the formed compounds were achieved by NMR spectroscopy. Particularly, the γ-gauche effect and long-range couplings were instrumental in assigning the stereochemistry of the adducts. However, in a recent paper, Novitskiy and Kutateladze claimed that based on an applied machine learning-augmented DFT method for computational NMR that the structure of the product, (1R,2R,3S,4S,7s)-2,3,7-tribromobicyclo[2.2.1]heptane was wrong. With the aid of their computational method, they revised a number of published structures, including ours, and assigned our product the structure (1R,2S,3R,4S,7r)-2,3,7-tribromobicyclo[2.2.1]heptane. To fit their revised structure, they proposed an alternative mechanism featuring a skeletal rearrangement without the intermediacy of a carbocation. Herein, we are not only confirming the structure origin...
Novel bromination reagents · hexabromocyclopentadiene: bromination of activated saturated sites
Tetrahedron Letters, 1984
Hexabromocyclopentadiene (HBC) readily brominates a-keto and benzylic sites, apparently by bromonium ion transfer. We have recently shown' that hexabromocyclopentadiene (HBC)(l) is a new and useful aromatic bromination reagent in that it performs site-selective electrophilic bromination of activated (electron rich) aromatic compounds. This was postulated to occur by bromonium ion release by virtue of aromatic stabilization of the cyclopentadienide counterpart which ends up as pentabromocyclopentadiene (2). We wish to report now that HBC(1) readily brominates ketones in a-position and alkyl aromatics in benzylic position, as shown in the Scheme and detailed in the Table. We tried aliphatic-(entries l-7), aromatic-(8-12), alicyclic-(13-17), B-dicarbonyl(l8-21) and a,@unsaturated(22,23) ketones and a small number of a-methylene aromatics (entries 24-27) using varying amounts of HBC. As before', the reactions were strongly dependent on solvent polarity; we worked in acetonitrile solutions at two temperatures: 70°C at which analytical/ kinetical runs were performed and monitored by NMR (in MeCN-d3) and at reflux (82°C) with
Chemosphere, 2011
Technical 1,2,5,6,9,10-hexabromocyclododecane (HBCD) consists largely of three diastereomers (a-, b-, and c-HBCD) produced by the trans addition of bromine to cis,trans,trans-cyclododeca-1,5,9-triene (CDT). However, another seven diastereomers are theoretically possible and may be produced by trans addition of bromine across the double bonds of the other three isomers of 1,5,9-CDT. There are indications that small amounts of the minor HBCD isomers may be present in commercial HBCD mixtures or in products containing this brominated flame retardant (BFR). Such minor components may indeed derive from traces of other 1,5,9-CDTs in the cis, trans, trans starting material, however their formation may also be possible through isomerizations during the processing of this BFR or by bioisomerization subsequent to its release into the environment. Two of the seven additional diastereomers (d-and e-HBCD) were synthesized previously from trans,trans,trans-CDT. We now report the preparation of the remaining five diastereomers, f-, g-, and h-HBCD from cis,cis,trans-CDT and iand j-HBCD from cis,cis,cis-CDT, and their characterization by 1 H NMR spectroscopy and X-ray crystallography. The availability of these further diastereomers of HBCD should aid in determining if the minor isomers are present in commercial samples of this BFR, in products containing HBCDs, or in environmental samples. We have also carried out an X-ray crystal structure determination on e-HBCD, so that crystal structures are now available for all 10 HBCD diastereomers.
Bromination of Decalin and Its Derivatives. 9. High Temperature Bromination
The Journal of Organic Chemistry, 1997
Thermal and photobromination of decalin, 1, was studied, trans,cis,trans-2,5,7,9-tetrabromooctalin, 2, was obtained as the major product along with smaller amounts of bromonaphthalene derivatives. The structures of the products were determined by 1 Hand 13 C-NMR data and single X-ray structural analysis. Bromination of the two decalin derivatives 9 and 10 results in the formation of single isomers 11 and 12, respectively. The three tetrabromides 2, 11, and 12 were shown by molecular mechanics calculations to be the most stable stereoisomer in each case. The formation of these tetrabromides under thermodynamic control is postulated.