58774-33-7Relevant academic research and scientific papers
The Mystery of the Benzene-Oxide/Oxepin Equilibrium—Heavy-Atom Tunneling Reversed by Solvent Interactions
Prado Merini, Melania,Sander, Wolfram,Schleif, Tim
supporting information, p. 20318 - 20322 (2020/10/02)
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.
Synthesis of (-)-Conduramine A1, (-)-Conduramine A2 and (-)-Conduramine E2 in Six Steps from Cyclohexa-1,4-diene
Da Silva Pinto, Solange,Davies, Stephen G.,Fletcher, Ai M.,Roberts, Paul M.,Thomson, James E.
supporting information, p. 7933 - 7937 (2019/10/10)
A method to enable the synthesis of conduramines and their N-substituted derivatives (enantiopure or racemic form) in six steps (five steps for N-substituted derivatives) from cyclohexa-1,4-diene is reported. Key features of this reaction sequence include a preparation of benzene oxide that is amenable to multigram scale, and its efficient ring-opening upon treatment with a primary amine. Epoxidation of the resultant amino alcohols (40% aq HBF4 then m-CPBA) is accompanied by hydrolytic ring-opening in situ to give the corresponding N-substituted conduramine derivatives directly. These may undergo subsequent N-deprotection to give the parent conduramines, as demonstrated by the preparation of enantiopure (-)-conduramine A1, (-)-conduramine A2, and (-)-conduramine E2 (the latter two for the first time). The selectivity of the epoxidation reaction is proposed to be the result of competitive ammonium-directed and hydroxyl-directed epoxidation processes, followed by either direct (SN2-type) or conjugate (SN2′-type) ring-openings of the intermediate epoxides.
Synthesis and Desymmetrization of meso Tricyclic Systems Derived from Benzene Oxide
Matías, Desirée M.,Johnson, Jeffrey S.
, p. 4859 - 4866 (2018/04/26)
Ozonolysis of the Diels-Alder adducts derived from benzene oxides and N-alkylmaleimides resulted in fully substituted, meso bicyclic systems bearing six contiguous stereocenters, isolated as diols upon reductive workup with NaBH4. Variation in the workup allowed for isolation of two different diastereoisomers, through double epimerization of the imide stereocenters. Desymmetrization of the resulting meso diols via asymmetric nucleophilic epoxide opening and acylation reactions provided access to highly substituted, enantioenriched fused rings.
Base-Mediated Fragmentation of Bicyclic Dihydro-3,6-oxazines: Transformation of Nitroso Diels-Alder Cycloadducts
Campagne, Rémy,Sch?kel, Friederike,Guillot, Régis,Alezra, Valérie,Kouklovsky, Cyrille
, p. 1884 - 1887 (2018/04/16)
Nitroso Diels-Alder cycloadditions of benzene oxide with various acyl-nitroso derivatives are described. Treatment of these cycloadducts with methyllithium results in a fast fragmentation reaction, leading to highly functionalized cyclic amino alcohols. T
Stereoselective syntheses of racemic quercitols and bromoquercitols starting from cyclohexa-1,4-diene: Gala-, epi-, muco-, and neo-quercitol
Aydin, G?kay,Savran, Tahir,Akta?, Fatih,Baran, Arif,Balci, Metin
, p. 1511 - 1524 (2013/05/21)
The efficient synthesis of gala-, epi-, neo-, and muco-quercitols and some brominated quercitols starting from cyclohexa-1,4-diene is reported. Treatment of the dibromide, obtained by the addition of bromine to cyclohexa-1,4-diene, with m-chloroperbenzoic
Is benzene oxide homoaromatic? A microcalorimetric study
Jia,Brandt,Thibblin
, p. 10147 - 10152 (2007/10/03)
Rate constants and heats of reaction for the aromatization of benzene oxide (1) and the acid-catalyzed aromatization of benzene hydrate (2) in highly aqueous solution giving phenol and benzene, respectively, have been measured by heat-flow microcalorimetry. The measured heat of reaction of benzene oxide, ΔH = -57.0 kcal mol-1, is much larger than that of benzene hydrate, ΔH = -38.7 kcal mol-1, despite an unusually low reactivity of benzene oxide, rate ratio 0.08. The measured enthalpies agree with those calculated using the B3LYP hybrid functional corrected with solvation energies derived from semiempirical AM1/SM2 calculations. Comparison with the measured enthalpies of the corresponding reactions of the structurally related 1,3-cyclohexadiene oxide (3) and 2-cyclohexenol (4) of ΔH = -24.9 kcal mol-1 (includes a small calculated correction of - 1.2 kcal mol-1) and ΔH ～ 0 kcal mol-1, respectively, gives a smaller aromatization energy for the benzene oxide than for the benzene hydrate reaction (ΔΔΔH = 6.6 kcal mol-l). This suggests that benzene oxide is unusually stabilized by a significant amount of homoaromatization as has been proposed previously (J. Am. Chem. Soc. 1993, 115, 5458). This unusual stability accounts for more than half of the ～107 times lower than expected reactivity of benzene oxide toward acid-catalyzed isomerization. The rest is suggested to originate from an unusually high energy of the carbocation-forming transition state.
?-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.
Synthesis of Cyclic Ethers via Bromine Assisted Epoxide Ring Expansion
Davies, Stephen G.,Polywka, Mario E. C.,Thomas, Susan E.
, p. 1277 - 1282 (2007/10/02)
Neighbouring group participation by epoxide oxygen in the opening of bromonium ions results in the stereoselective synthesis of cyclic ethers. 9-Oxabicyclonon-4-ene gives trans, trans-2,6-dibromo-9-oxabicyclononane and trans,trans-2,5-dibromo-9-oxabicyclononane.Sequential bromination and Bu3SnH reduction converts 1,2-epoxyhex-5-ene into cis- and trans-2,5-dimethyltetrahydrofuran and 2-methyltetrahydropyran while (+)-cis-limonene oxide is converted into non-chiral cineole.
