Product Code Database
The name dendralene is pulled together from the words dendrimer, linear and alkene. The higher dendralenes are of scientific interest because they open up a large array of new from a relatively simple precursor especially by Diels-Alder chemistry. Their cyclic counterparts are aptly called .
This compound reacts with two equivalents of maleic anhydride in a tandem DA reaction:
With benzoquinone the reaction product was a linear polymer.
Several syntheses of substituted 3dendralenes have been reported, one via an allene, one via a Horner–Wadsworth–Emmons reaction, one via a cross-coupling reaction and one from an allylic carbonate.
One synthetic route to 4dendralene starts from chloroprene. This compound is converted to a Grignard reagent by action of magnesium metal which is then reacted with copper(I) chloride to an organocopper intermediate which is in turn dimerized using copper(II) chloride in an oxidative coupling reaction to give the butadiene dimer called 4dendralene.
The 8-dendralene compound was reported in 2009:
in a successive Kumada–Tamao–Corriu coupling and Negishi coupling.
A series of 9 to 12-dendralenes has been reported in 2016
4dendralene shows a tandem reaction Diels-Alder reaction with the dienophile N-methyl-maleimide (NMM). Complete site selectivity is possible with the addition of the Lewis acid methyldichloroaluminium. With one set of premixing and 2 equivalents of NMM, the central diene group is targeted to the monoadduct 3. With another set and a larger amount of dienophile, the terminal groups react and the reaction proceeds from the monoadduct to the trisadducts 2 and 2b.
One reaction variation is cyclopropanation to a compound class called ivyanes with a reported synthesis in a Simmons–Smith reaction (diethyl zinc / trifluoroacetic acid) of the first 6 members. These 1,1-oligocyclopropanes are stable (except when exposed to acids) and have a large heat of combustion with 6ivyane exceeding that of cubane. The oligocyclopropane chains adopt a helical conformation. For 3dendralene a photochemical cyclisation reaction has been reported
|
|
