- From phenols to azulenes: An extended and versatile route to polyalkylated azulenes with variable substitution patterns at the seven- and five-membered ring
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Polyalkylated azulenes can easily be prepared from polyalkylphenyl propiolates which are transformed by dynamic gas phase thermo-isomerization (DGPTI) into polyalkylcyclohepta[b]furan-2(2H)-ones. The latter react thermally with enol ethers or enamines to the corresponding azulenes. The enamines may be generated in situ from corresponding aminals, especially, in cases where it is difficult to obtain the pure enamines due to their high re-activity.
- Nagel, Matthias,Hansen, Hans-Jürgen
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p. 692 - 696
(2007/10/03)
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- Cyclopentenone Derivatives, V. Stereoselective Cyclopentanone Anellations
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1,3 or 1,4 located donating centers in additions to 4-acetoxy-2-cyclopenten-1-one (1) stereoselectively give rise to cyclic cis anellation products (5, 13, 16, 20 - 22) which depending on substituents may be opened to cis disubstituted cyclopentanone derivatives (5 -> 10).Starting with the 1,5 located donor 19d corresponding trans hydroazulene derivative (23) is formed.This way an intermediate for a simple total synthesis of vetivazulene (29) is obtained.
- Harre, Michael,Winterfeldt, Ekkehard
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p. 1437 - 1447
(2007/10/02)
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