A fascinating re-examination has appeared[cite]10.1002/anie.201505482[/cite] of a reaction first published[cite]10.1002/ange.19600721210[/cite] in 1960 by Wittig and then[cite]10.1002/jlac.19646790106[/cite] repudiated by him in 1964 since it could not be replicated by a later student.
AbstractNickel was identified as a catalyst for the cyclopropanation of unactivated olefins by using in situ generated lithiomethyl trimethylammonium triflate as a methylene donor. A mechanistic hypothesis is proposed in which the generation of a reactive nickel carbene explains several interesting observations. Additionally, our findings shed light on a report by Franzen and Wittig published in 1960 that had been retracted later owing to irreproducibility, and provide a rational basis for the systematic development of the reaction for preparative purposes as an alternative to diazomethane or Simmons–Smith conditions.
AbstractTrimethylammoniummethylid (I) war unter den hier gewählten Versuchs‐bedingungen nicht befähigt, Cyclohexen zum Norcaran abzuwandeln, da es entweder die Stevens‐Isomerisation zum Dimethyläthylamin einging oder Polymethylen bildete. Auch bei der Metallierung von Chlormethyl‐trimethyl‐ammoniumchlorid in Anwesenheit von Cyclohexen wurde die Cyclopropanierung durch Konkurrenzreaktionen unterdrückt. Die aus Butoxymethyl‐ und Phenoxy‐methyl‐trimethyl‐ammoniumsalzen entstehenden N‐Ylide waren geeignet, Cyclohexen in das Butoxy‐ bzw. Phenoxy‐norcaran zu überführen.
Related Article: P.Buchalski, I.Grabowska, E.Kaminska, K.Suwinska|2008|Organometallics|27|2346|doi:10.1021/om701275u