52306-31-7Relevant academic research and scientific papers
Sulphide as a leaving group: Highly stereoselective bromination of alkyl phenyl sulphides
Canestrari, Daniele,Cioffi, Caterina,Biancofiore, Ilaria,Lancianesi, Stefano,Ghisu, Lorenza,Ruether, Manuel,O'Brien, John,Adamo, Mauro F.A.,Ibrahim, Hasim
, p. 9042 - 9050 (2019/10/22)
A conceptionally novel nucleophilic substitution approach to synthetically important alkyl bromides is presented. Using molecular bromine (Br2), readily available secondary benzyl and tertiary alkyl phenyl sulphides are converted into the corresponding bromides under exceptionally mild, acid- and base-free reaction conditions. This simple transformation allows the isolation of elimination sensitive benzylic β-bromo carbonyl and nitrile compounds in mostly high yields and purities. Remarkably, protic functionalities such as acids and alcohols are tolerated. Enantioenriched benzylic β-sulphido esters, readily prepared by asymmetric sulpha-Michael addition, produce the corresponding inverted bromides with high stereoselectivities, approaching complete enantiospecificity at -40 °C. Significantly, the reported benzylic β-bromo esters can be stored without racemisation for prolonged periods at -20 °C. Their synthetic potential was demonstrated by the one-pot preparation of γ-azido alcohol (S)-5 in 90% ee. NMR studies revealed an initial formation of a sulphide bromine adduct, which in turn is in equilibrium with a postulated dibromosulphurane intermediate that undergoes C-Br bond formation.
Solvent free, light induced 1,2-bromine shift reaction of α-bromo ketones
An, Sejin,Moon, Da Yoon,Park, Bong Ser
, p. 6922 - 6928 (2018/10/24)
Photolysis of α-bromopropiophenones in acetonitrile results in formation of β-bromopropiophenones with good product selectivity, which can be coined as 1,2-Br shift reaction. The product selectivity increases when the reaction is done in neat or solid state, where only the 1,2-Br shift product is formed in some cases. The reaction is suggested to proceed by C–Br bond homolysis to give a radical pair, followed by disproportionation and conjugate addition of HBr to the α,β-unsaturated ketone intermediate. When the unsaturated intermediate is stabilized by an extra conjugation, the reaction stops at the stage, in which the unsaturated ketone becomes a major product. The synthetic method described in this research fits in a category of eco-friendly organic synthesis nicely since the reaction does not use volatile organic solvents and any other additives such as acid, base or metal catalysts, etc. Besides, the method fits into perfect atom economy, which does not give any side products. The synthetic method should find much advantage over other alternative methods to obtain β-bromo carbonyl compounds.
Photoinduced C-N bond cleavage in 2-azido-1,3-diphenyl-propan-1-one derivatives: Photorelease of hydrazoic acid
Klima, Rodney F.,Jadhav, Abhijit V.,Singh, Pradeep N. D.,Chang, Mingxin,Vanos, Christine,Sankaranarayanan, Jagadis,Vu, Mai,Ibrahim, Nazarin,Ross, Elaine,McCloskey, Shaun,Murthy, Rajesh S.,Krause, Jeanette A.,Ault, Bruce S.,Gudmundsdottir, Anna D.
, p. 6372 - 6381 (2008/02/11)
(Chemical Equation Presented) Photolysis of 3-azido-1,3-diphenyl-propan-1- one (1a) in toluene yields 1,3-diphenyl-propen-1-one (2), whereas irradiation of 3-azido-2,2-dimethyl-1,3-diphenyl-propan-1-one (1b) results in the formation of mainly 2,2-dimethyl-1,3-diphenyl-propan-1-one. Laser flash photolysis (308 nm) of 1a,b in acetonitrile reveals a transient absorption (λmax = ～310 nm) due to the formation of radicals 4a and 4b, respectively, which have lifetimes of ～14 μs at ambient temperature. TD-DFT calculations (B3LYP/6-31+G(d)) reveal that the first and second excited states of the triplet ketone (T1K (n,π*) and T2K (π,π*)) in azide 1a are almost degenerate, at ～74 and 76 kcal/mol above the ground state (S0), respectively. Similarly, azide 1b has T1K and T2K 75 and 82 kcal/mol above S0, respectively. The calculated transition state for cleaving the C-N bond is located 71 and 74 kcal/mol above S0 in azides 1a and 1b, respectively. The calculated bond dissociation energies for breaking the C-N bond are 55 and 58 kcal/mol for azides 1a and 1b, respectively, making C-N bond breakage accessible from T 1K in azides 1 at ambient temperature. In comparison, the irradiation of azides 1 in argon matrices at 14 K lead to the formation of the corresponding triplet alkyl nitrenes (1-n), via intramolecular energy transfer from T2K- The characterization of 1-n was supported by isotope labeling, IR spectroscopy, and molecular modeling.
Lewis acid catalyzed reaction of aromatic vinyl halides with aromatic aldehydes: A novel aldol-type condensation mimic
Chan,Kamijo,Yamamoto
, p. 910 - 913 (2007/10/03)
In the presence of catalytic amounts of Lewis acid, aromatic α-vinyl halides readily undergo reaction with aromatic aldehydes at ambient temperatures to give a variety of substituted transchalcones in moderate to excellent yields. These compounds are potentially useful synthetic intermediates for organic synthesis as well as compounds of significance in terms of their ability to exhibit a wide spectrum of biological activity. This is the first reported example in which haloalkenyl derivatives other than metallooxyalkenes can participate in the Mukaiyama-aldol type carbon-carbon formation reaction.
Substituent Effects in 13C-N.M.R. Spectra of Diastereomeric Chalcone Dihalogenides. VIII. Investigations of α- and β-Halogene Dihydrochalcones and Calculation of 13C-chemical Shifts of Diastereomeric Chalcone Dihalogenides and Chalcone Halogenohydrins
Weber, F. G.,Radeglia, R.
, p. 212 - 222 (2007/10/02)
The chemical shifts of C-α and C-β in the 13C-n.m.r. spectra are determined and compared with calculated values from an incremental system and Taft relationship.The correlations are extended for erythro and threo isomers of halohydrins and diastereomeric
GAS-SOLID REACTIONS IN ORGANIC SYNTHESIS
Kaup, Gerd,Matthies, Doris
, p. 119 - 143 (2007/10/02)
Various new branches in the field of preparative scale organic gas-solid reactions (additions, substitutions, eliminations, condensations) are elaborated following a historical review.Polar gases (HBr, HCl, HI, HSCH3) react at 1 bar and temperatures from 40 to -80 degC with gram quantities of crystalline N-vinylimides, -amides, -amines, and S-vinylthioethers usually in the Markovnikov orientation, but there is also an exception.The polar gases H2O and NH3 transform some of the crystalline addition products and H2O may be added catalytically to N-vinylphthalimide.All reactions run to high conversion rapidly and several of the highly sensitive products cannot be synthesized in soluton.Liquid compounds like N-vinylpyrrolidinone which polymerize in solution crystallize and add polar gases smoothly upon freezing.Polar gases are applied to crystalline chalcone, cinnamic acid, and stilbenes with variable success.Pd-doped crystals are hydrogenated.Contrary to literature reports chlorine and bromine add to crystalline stilbene non-stereospecifically and without significant substitution.The results are discussed with respect to X-ray structures and powder diffraction patterns.Educt and product crystals are not isotypical.Various solid state decompositions are uncovered and the synthetic value is stressed.
Organic Gas-Solid Reactions with Stilbenes, Chalcones, and Enamides
Kaupp, Gerd,Matthies, Doris
, p. 1897 - 1904 (2007/10/02)
Crystalline stilbene (1) adds gaseous chlorine and bromine without intermediate melting.The stereoselectivity is similar to that observed in solutions.Triphenylethene (3) also yields the products 4 in gas-solid reactions with chlorine and bromine, but these products tend to loose HX from the crystal; their conversion products are described.Neither crystalline 1 nor 3, but (E)-1,2-diphenyl-1-propene (7) adds gaseous hydrogen bromide regiospecifically.The same is true for the crystalline chalcone 10, which adds hydrogen bromide and -chloride selectively to give 11 nonisotypically.Gaseous ammonia reconverts crystalline 11 into 10.The enamide 12 in its crystalline state adds the gases hydrogen bromide, -chloride, methanethiol and hydrogen, to give the products 13, but also 15 (addition and condensation) and 16 (double addition). 13f which is formed via hydrogenation of crystals is not isotypical with its precursor 12.The liquid 17 crstallizes on freezing and then easily adds the gases hydrogen bromide (> - 50 deg C) and hydrogen chloride (> - 80 deg C) in highly controlled reactions to give the reactive compounds 18.These are converted not only into oligomers but also into the derivatives 19, 20, 21, and 22.The advantages of the unusual reaction procedures are discussed.
Structure and Stereochemistry of the Dehydrobromination of some β-Bromo Ketones Derived from Alkyl Phenyl Ketones and Benzaldehyde
Quast, Helmut,Mueller, Bodo,Peters, Karl,Schnering, Hans Georg von
, p. 1525 - 1546 (2007/10/02)
The aldol reaction of alkyl phenyl ketones with benzaldehyde in the presence of hydrogen bromide affords diastereomeric β-bromo ketones under thermodynamic control.Thus, from propiophenone (8a) two diastereomeres 9a are obtained in a 67 : 33 ratio, while
