A Tubular Structural Analogue of Helicene

Key words

helical structures - Friedländer condensation

Significance

Helical molecular systems, both natural and unnatural, continue to capture the interests of chemists. Using an enantiomerically pure bicyclic moiety to appropriately place kinks into the system, Wärnmark and co-workers report the synthesis of helical structure 1, an orthogonal topological analogue of helicene.

 

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Comment

The synthesis of 1 is accomplished by repeated employment of a two-step set of reactions consisting of (1) ring-opening hydrolysis in acid and (2) Friedländer condensation with a chiral bicyclic ketone. By this strategy, monomer 2 is converted into ring-opened trimer 3, which is converted into trimeric ketone 4. Condensation of 4 and 3 affords the helical target 1.

 

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