Unexpected Zwitterionic Allenyls from Silylenes and a Fischer Alkynylcarbene: A Remarkable Silylene‐Promoted Rearrangement

• Published in: Chemistry : a European journal Vol. 25; no. 9; pp. 2222 - 2225
• Main Authors: Cabeza, Javier A., García‐Álvarez, Pablo, Gómez‐Gallego, Mar, González‐Álvarez, Laura, Merinero, Alba D., Sierra, Miguel A.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 11-02-2019
• Subjects: 1,3-metal shift; Allene; allenyl ligands; Chemistry; Fischer carbenes; silicon; silylenes; Zwitterions; silicon; allenyl ligands; 1,3-metal shift; silylenes; Fischer carbenes
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201806275

The silylenes Si(tBu2bzam)R (tBu2bzam=N,N′‐bis(tertbutyl)benzamidinate; R=mesityl, CH2SiMe3) attack the Ccarbene atom of the Fischer alkynyl(ethoxy)carbene complex [W(CO)5{C(OEt)C2Ph}] to give, after a striking rearrangement, zwitterionic σ‐allenyl complexes in which the original carbene C atom forms part of the allene C3 fragment and also of a Si‐C‐N‐C‐N five‐membered ring after insertion into a Si−N bond of the original amidinatosilylene. These remarkable allenyl products, which contain two stereogenic groups, are selectively formed as single diastereomers.
A striking stereoselective rearrangement, which ends in unprecedented zwitterionic allenyls having one end of the allene C3 fragment inserted into a Si−N bond, takes place in reactions of amidinatosilylenes with a Fischer alkynylcarbene.