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As long as 50 years ago theoretical calculations predicted that M??bius annulenes with only one ?? surface and one edge would exhibit peculiar electronic properties and violate the H??ckel rules. Numerous synthetic attempts notwithstanding, the first singly twisted M??bius annulene was not prepared until 2003. Here we present a general, rational strategy to synthesize triply or even more highly twisted cyclic ?? systems. We apply this strategy to the preparation of a triply twisted [24]dehydroannulene, the structure of which was confirmed by X-ray analysis. Our strategy is based on the topological transformation of 'twist' into 'writhe'. The advantage is twofold: the product exhibits a lower degree of strain and precursors can be designed that inherently include the writhe, which, after cyclization, ends up in the M??bius product. With our strategy, triply twisted systems are easier to prepare than their singly twisted counterparts.


Schaller, G. R.; Topi, F.; Rissanen, K.; Okamoto, Y.; Shen, J.; Herges, R.  Nat. Chem. 2014, 6, 608-613Contributed by Steven Bachrach.Reposted from Computational Organic Chemistry with permissionHerges and co-workers have prepared a triply-twisted Mbius...
Herges and co-workers have prepared a triply-twisted Möbius molecule. 1 The key element is recognizing that most of the twisting needs to be accomplished through writhe, a twisting that produces figure-8-like crossing, the way an old-school phone cord...
Scientists have managed to make a triple-Mbius annulene, the most twisted fully conjugated molecule to date. An everyday analogue of a single twisted Mbius molecule is a Mbius strip. It can be made easily by twisting one end of a paper strip by 180 degrees...