- Dialkylated Dihydroazulene and Vinylheptafulvene Derivatives – Synthesis and Switching Properties
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Functionalization of molecular photoswitches at specific positions offers a way of tuning their switching properties. The work presented here describes the development of a new protocol towards the synthesis and functionalization of the dihydroazulene/vinylheptafulvene (DHA/VHF) photo-/thermoswitch. The key step is a facile condensation reaction using a functionalized tropone derivative, and the new synthetic method was employed in the regioselective preparation of a novel dimethyl-substituted DHA photoswitch. This compound presents the first accessible derivative with alkyl groups on the seven-membered ring of the system ― at positions C5 and C7. From experimental and theoretical kinetics studies on the thermal VHF-to-DHA electrocyclic reaction, the influence of the electron-donating methyl groups was elucidated. In addition, we subjected a small selection of 4,8a-dialkylated compounds to a computational study to elucidate how steric interactions can alter the relative DHA–VHF stabilities. The synthetic methodology offers access to novel DHA scaffolds and substitution patterns, which in turn can lead to systems that can help to address broader questions concerning the potential applicability of the DHA/VHF system in the context of solar-thermal energy-storage systems or other photochromic applications.
- Lubrin, Nickie C. M.,Vlasceanu, Alexandru,Frandsen, Benjamin N.,Skov, Anders B.,Kilde, Martin Dr?hse,Mikkelsen, Kurt V.,Nielsen, Mogens Br?ndsted
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supporting information
p. 2932 - 2939
(2017/06/06)
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- Regiochemistry in alkylation, acylation and methoxycarbonylation of alkali salts from 2-substituted alkenylpropanedinitriles
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Alkali salts (4-) of several 2-substituted alkenylpropanedinitriles are prepared, isolated and characterised by 1H and 13C NMR spectroscopy. By treating the salt 4a- with 4a a dimer, 2-dicyanomethylene-6-methyl-4,6-diphenyl-1,2,5,6-tetrahydronicotinonitrile 6, is formed, for which a single-crystal X-ray structure is presented. Alkylation of the ambident salts 4- with MeX (X = I, Tf, or Br) leads to regioisomers, 1-and 3-alkylation, and comparison with O vs. C-alkylation of ketones is made. Double alkylation is also observed, 3-alkylation followed by 1-alkylation. Thus from 4a- a mixture of (E)-and (Z)-2-methyl-2-(1-phenylprop-1-enyl)propanedinitrile 9b is formed, and the X-ray structure of the former is presented. Acylation of 4a- with benzoyl chloride gives only the 3-regioisomer; using equimolar amounts of reactants gives a ring-closure product, 2-oxo-4,6-diphenyl-2H-pyran-3-carbonitrile 12, while excess of benzoyl chloride gives the double-acylation product, (Z)-4,4-dicyano-1,3-diphenylbuta-1,3-dienyl benzoate (Z)-13, for which the X-ray structure is presented. Acylation of 4a- with acetyl chloride gives both regioisomers; the 1-acylated product evaded isolation, and the 3-acylation product reacted further to give the (E)- and (Z)-form of 4,4-dicyano-1-methyl-3-phenylbuta-1,3-dienyl acetate 15. The X-ray structure of the latter isomer, (Z)-15, is presented. Methoxycarbonylation of salts 4- with methyl chloroformate gives both regioisomers, while use of methyl cyanoformate gives only the 3-regioisomer, in addition to a Michael adduct from reaction of the CN- group with protonated salt 4-.
- Karlsen, Hege,Songe, Pal H.,Sunsby, Lise Kristin,Hagen, Lise Cathrine,Kolsaker, Per,Romming, Christian
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p. 497 - 507
(2007/10/03)
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- Study of Mechanism of Reduction of 2-Bromo-1-(p-X-phenyl)ethylidenemalonitrile by 1-Benzyl-1,4-dihydronicotinamide and 10-Methyl-9,10-dihydroacridine
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The reduction of 2-bromo-1-(p-X-phenyl)ethylidenemalonitrile (X-BPM: X=H, F, Cl, Br, CN) by NADH models BNAH and AcrH2 has been investigated.Based on product analysis, kinetic isotope effect, and free energy relationship, a direct hydride transfer and an
- Liu, You-Cheng,Li, Bin,Guo, Qing-Xiang
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p. 9671 - 9680
(2007/10/02)
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- Formation of Cyclopropanes from 2-Bromo-1-phenylalkylidenemalononitriles and Nucleophiles
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The reaction of the title compounds with selected nucleophiles was studied.With cyanide and hydride (from sodium borohydride) ions, substituted cyclopropanes were obtained in good yields.With alkoxide ions, cyclopropanes were formed only when the bromide
- Berg, Arne,Kolsaker, Per
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p. 289 - 294
(2007/10/02)
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