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Intramolecular C−H Insertion Reactions of Boroxy Fischer Carbene Complexes. Regio- and Diastereoselective Modification of Terpenes

1999; American Chemical Society; Volume: 121; Issue: 38 Linguagem: Inglês

10.1021/ja991161+

1943-2984

José Barluenga, Félix Rodríguez, Jérôme Vadecard, Maximilian Bendix, Francisco J. Fañanás, Fernando López Ortiz, Miguel A. Rodrı́guez,

Catalytic C–H Functionalization Methods

In-situ-generated dialkylboroxy and diaminoboroxy Fischer carbene complexes lead to oxaborolane or oxazaborolidine derivatives via an intramolecular C−H insertion reaction. Further oxidation of these intermediates yields 1,3-diol or 1,2-amino alcohol derivatives. Diastereoselectivities as high as 99% are reached when starting from boroxy Fischer carbene complexes derived from terpenes, which represents a regio- and diastereoselective modification of this type of natural product. The influence of the Cβ substituents relative to the boron atom on the reaction path is studied, and a mechanism is proposed after identification of an intermediate by NMR. In addition, theoretical calculations show the presence of a boron−metal interaction, which could result as key step to the C−H insertion reaction.