Zusammenfassung
The vinylheptafulvene (VHF) to dihydroazulene (DHA) electrocyclization is known to proceed from an s-cis conformation of VHF and cannot occur from the more stable s-trans conformation. Locking the VHF in the s-cis conformation by the introduction of a dihydronaphthalene (DHN) unit has been found to greatly enhance the speed of this reaction. Thus, the half-life was reduced by more than a factor ...
Zusammenfassung
The vinylheptafulvene (VHF) to dihydroazulene (DHA) electrocyclization is known to proceed from an s-cis conformation of VHF and cannot occur from the more stable s-trans conformation. Locking the VHF in the s-cis conformation by the introduction of a dihydronaphthalene (DHN) unit has been found to greatly enhance the speed of this reaction. Thus, the half-life was reduced by more than a factor of 150000 in cyclohexane and by a factor of approximately 950000 in ethanol. In addition, the characteristic absorption of the photoactive DHA isomer, now annulated to DHN, exhibited a desired redshift relative to the parent compound. Here, we present the synthesis and study of these DHN-DHA/VHFs, including a protocol for the incorporation of a pseudo-halide to enable the further functionalization of the molecule by metal-catalyzed cross-coupling reactions. For proof-of-concept, two different sulfur end-groups were incorporated as anchoring groups for potential molecular electronics applications.
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