research report      name index      key word index      corresp.unit            Page in german      Imprint + Privacy Policy   

Third-party-funded project

Title:
Strained Cycloallenes

Project management at the University of Würzburg:

Participating scientists:

Abstract:
The extremely short-lived intermediates cyclohexa-1,2,4-triene, 2,3-didehydro-1,2-dihydronaphthalene, and 1-methyl-1-azacyclohexa-2,3-diene(B-N)borane were generated by ß-elimination. Their existence was proven by interception in terms of cycloadditions with activated olefins such as furan and styrene. In the case of cyclohexa-1,2,4-triene and 2,3-didehydro-1,2-dihydronaphthalene, it could be shown that these intermediates are deprotonated by the strong base, necessary for the generation, to give the phenyl- and the 2-naphthylanion, respectively. The dimerisation of chiral allenes takes different stereochemical courses for pairs of enantiomers and pairs of homomers. Thus, a remarkable example for molecular recognition is provided by 1-phenylcycloocta-1,2-diene, as the racemate furnishes the virtually pure cis-dimer, whereas pure enantiomers give rise to the almost pure nonracemic trans-dimers.

Key words:
    Cyclohexa-1,2,4-triene
    2,3-Didehydro-1,2-dihydronaphthalene
    1-Methyl-1-azacyclohexa-2,3-diene(B-N)borane
    Hexahydroepoxyquinoline
    Hexahydrocyclobutapyridine
    1,3-Diphenylallene
    1-Phenylcyclonona-1,2-diene
    1-Phenylcycloocta-1,2-diene
    1,2-Bismethylenecyclobutanes

Projekt period: from 01.1999 to 12.2001

Funding institution:
DFG ,Granting date: 15.12.1998

Publications: