Coming Back to the Starting Position of Carbons Traveling in Organic Molecules on Titanium: Merry-Go-Round Reaction

Abstract

Traveling of carbon atoms in organic molecules was successfully achieved. The six-membered ring of dihydroindenyl moiety on titanium rotated based on the five-membered ring like a merry-go-round. Two carbons at the bridgehead of the dihydroindenyl moiety and the other three carbons of the five-membered ring were monitored by 13C-labeled experiments. The two carbons at the bridgehead moved to the farthest positions with the rotation of the six-membered ring. The intermediate where the two carbons were located at the farthest positions was isolated and fully characterized. Treatment of the intermediate with azobenzene made the two carbons come back to the starting positions. There is another viewpoint on this reaction. When the six-membered ring is fixed and the movement of three carbons of the five-membered ring of the dihydroindenyl moiety on titanium is focused, it was found that those three carbons moved around the six-membered ring and came back to the starting points.

Update for Reactions of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes: A Never-Ending Story?

“…In a more recent study by Takahashi and coworkers, the term “ merry-go-round reaction ” was used for reaction pathways in which C atoms in molecules change their positions step by step and finally return to to their starting point (Scheme ). This was reported very recently for the traveling of C atoms at a titanium center, which proceeds via rotation of two C atoms in a six-membered ring of a dihydroindenyl moiety .…”

Vivid Wording for the Chemistry of Group 4 Metallocene Complexes

“…It was recently evoked by Takahashi et al. to describe the traveling of C‐atoms in organotitanium molecules with a rotation of two C‐atoms and a rotation of the six‐membered ring in the dihydroindenyl moiety on titanium [8a] . Before these studies, Takahashi and co‐workers investigated these and related systems in detail and used them for very interesting synthetic purposes [6] coming at the end to the mentioned “merry‐go‐round reaction” [8a] …”

“…All these contributions provide the background for a recent contribution from the Takahashi group that describes the traveling of C atoms in such titanium‐bonded ligands with the result that the C atoms return to the starting position, hence the name “merry‐go‐round reaction” (Scheme 9). [8a] …”

Anschauliche Bezeichnungen der Chemie von Metallocen‐Komplexen der Gruppe 4

“…Kürzlich wurde durch Takahashi et al. die “Reise” von C‐Atomen in Organometallmolekülen des Titans mit einer Rotation von zwei C‐Atomen und einer weiteren Rotation im sechsgliedrigen Ring der Dihydroindenyleinheit am Titan publiziert [8a] . Vor diesen Untersuchungen untersuchten Takahashi und Mitarbeiter solche sowie verwandte Systeme im Detail zur Verwendung für hochinteressante Synthesezwecke, [6] um letztendlich zur “merry‐go‐round‐reaction” zu kommen [8a] …”

“…Alle diese Beiträge bilden die Grundlage für die von der Gruppe um Takahashi publizierten Ergebnisse, die die Wanderung von C‐Atomen in solchen an Titan gebundenen Liganden mit dem Ergebnis zeigen, dass die C‐Atome wieder in ihre Anfangsposition gelangen, woher der Name “merry‐go‐round‐reaction” kommt (Schema 9). [8a] …”