Synthese und1H-NMR-Analyse von Triafulvalen-Vorstufen

Syntheses ofgem-Dihalocyclopropanes and Their Use in Organic Synthesis

“…Its cycloaddition to unsaturated hydrocarbons and alkenes possessing functional groups proceeds rapidly. Many examples of these reactions have been published in the last seven years. ,,,,,,,,− ,,,,,,,,,,,,− …”

Reactions of endo-3-Diazotricyclo[3.2.1.02,4]oct-6-ene, a Potential Precursor for the Generation of a Neutral C8H8 Molecule with a Pyramidally Coordinated Carbon

“…However, the intermediacy of 1 could not yet be established because only dimerization of 5 was observed. 8 It will be shown in this paper that 1 is not the only neutral molecule with a pyramidally coordinated carbon that might be experimentally accessible. Indeed, the chemistry of endo-3diazotricyclo[3.2.1.0 2,4 ]oct-6-ene (endo-6) has already been investigated by Kirmse 9 who considered the intermediacy of the pyramidally coordinated cation 4+ during the decomposition of endo-6 in methanol.…”

“…Recently, DFT calculations suggested that pentacyclo[4.3.0.0 2,9 .0 3,8 .0 7,9 ]non-4-ene ( 1 ), a [4.3.4.3]fenestrane, could be generated from the corresponding cyclopropylidene, tricyclo[3.2.2.0 2,4 ]nona-6,8-dien-3-ylidene ( 5 ). However, the intermediacy of 1 could not yet be established because only dimerization of 5 was observed …”

Synthesis and Properties of Oligocyclopropyl-Containing Natural Products and Model Compounds

“…An interesting new perspective for the synthesis of oligocyclopropane 193 was based on the work of Neuenschwander et al . − Dibromocyclopropane 161 , available by addition of a dibromocarbene to olefin 137b , was coupled under thermodynamic conditions to yield a mixture of four isomeric bicyclopropylidenes 162 (Scheme ). Unfortunately, separation of the diastereoisomers was not possible; however, it can be assumed that by starting from nonracemic 137b and 161 , respectively, the number of isomers could be reduced.…”