291-70-3Relevant articles and documents
The Mystery of the Benzene-Oxide/Oxepin Equilibrium—Heavy-Atom Tunneling Reversed by Solvent Interactions
Prado Merini, Melania,Sander, Wolfram,Schleif, Tim
, p. 20318 - 20322 (2020)
The equilibrium between benzene oxide (1) and oxepin (2) is of large importance for understanding the degradation of benzene in biological systems and in the troposphere. Our studies reveal that at cryogenic temperatures, this equilibration is governed by rare heavy-atom tunneling. In solid argon at 3 K, 1 rearranges to 2 via tunneling with a rate constant of approximately 5.3×10?5 s?1. Thus, in a nonpolar environment, 2 is slightly more stable than 1, in agreement with calculations at the CCSD(T) level of theory. However, if the argon is doped with 1 % of H2O or CF3I as typical hydrogen or halogen bond donors, respectively, weak complexes of 1 and 2 are formed, and now 2 is tunneling back to form 1. Thus, by forming non-covalent complexes, 1 becomes slightly more stable than 2 and the direction of the heavy-atom tunneling is reversed.
?-Facial stereoselectivity in the Diels-Alder reactions of benzene oxides
Gillard, James R.,Newlands, Michael J.,Bridson, John N.,Burnell, D. Jean
, p. 1337 - 1343 (2007/10/02)
The Diels-Alder reactions of N-phenylmaleimide and dimethyl acetylenedicarboxylate with benzene oxide (1,3,5-cyclohexatriene 1,2-oxide, 3) and its more substituted derivatives 1,2-dimethyl-1,3,5-cyclohexatriene 1,2-oxide (7) and 10-oxatricyclodeca-2,4-diene (11) in a kinetic manner gave exclusively products of addition anti to the plane-nonsymmetrical oxygen.The structures of the adducts were determined unequivocally by nuclear Overhauser enhancements in their 1H nuclear magnetic resonance spectra and by X-ray crystallographic methods.The ?-facial stereoselectivity was rationalized in terms of unfavorable orbital interactions, steric hindrance between the dienophile and the syn face of benzene oxide, and ?-donation by the oxygen. Key words: cycloaddition, Diels-Alder, syn-anti, ?-facial stereoselectivity, benzene oxide.
On the cis-Glycol and the Epoxide of Benzvalene
Christl, Manfred,Leininger, Hartmut,Kemmer, Petra
, p. 2963 - 2987 (2007/10/02)
By means of standard methods, benzvalene (1) can be transformed into the cis-glycol 2, from which derivatives such as the ditosylate 3, the cyclic carbonate 4, and the cyclic orthoacetates 5 and 6 are readily prepared.Irradiation causes thiophenol to add across the central bond of the bicyclobutane moiety of 2 with formation of the thioether 8.The solvolysis of 3 in aqueous acetone leads to endo,endo-tricyclo2,6>hexane-3,5-diol (11). - The epoxide 18 of benzvalene (1) may be synthesized starting either from the orthoesters 6 via the trans-chlorohydrin acetate 17 or directly from 1 with N-benzoylpercarbamidic acid, the latter reaction being the better one.Initially, the thermolysis of 18 produces 2-oxabicyclohepta-3,6-diene (19) which in part isomerizes to oxepin (20)/benzene oxide (21).In the thermal decomposition of 3,4-dideuterated 18, the labels end up in positions 5 and 6 of 19.If 18 is thermolyzed in high concentration 19, and 21 undergo Diels-Alder addition to a considerable extent to form the pentacyclic product 22.Epoxide 18 adds acetic acid and, under irradiation, thiophenol resulting in 1:1 adducts of the tricyclo2,6>hexane type (29 and 28, respectively).On slight warming, the diol monoacetate 29 rearranges to the corresponding bicyclohex-2-ene derivative 30, which is converted into its bicyclohex-2-ene isomer 31 at 130 deg C.Depending on the solvent and the temperature, LiAlH4 reduces 18 either to almost pure tricyclo2,6>hexan-3-ol (32) or to a 1:1 mixture of 32 and endo-tricyclo2,6>hexan-3-ol (33).On the basis of the NMR data of the corresponding methyl ethers 34 and 35, a structure assignment in the literature has to be revised.
