Reversible oxidative Addition an Kohlenstoff

Es wird die Reaktivitat N-heterocyclischer Carbene (NHCs) und cyclischer Alkylaminocarbene (cAACs) gegenuber Arylboronsaureestern vorgestellt. Die Reaktionen mit NHCs fuhren zur reversiblen Bildung thermisch stabiler Lewis-Saure-Base-Addukte Ar-B(OR)2⋅NHC (Add1–Add6). Die Umsetzungen von cAACMe mit den Catecholboronsaureestern 4-R-C6H4Bcat (R=Me, OMe) liefern die Addukte 4-R-C6H4Bcat⋅cAACMe (Add7, R=Me) und (Add8, R=OMe), die bei Raumtemperatur zu den cAACMe-Ringerweiterungsprodukten RER1 und RER2 reagieren. Die Boronsaureester Ar-B(OR)2 des Pinakols, Neopentylglykols und Ethylenglykols reagieren bei Raumtemperatur mit cAACMe unter reversibler oxidativer Addition der B-C-Bindung an das Carben-Kohlenstoffatom zu cAACMe(B{OR}2)(Ar) (BCA1–BCA6). NMR-spektroskopische Untersuchungen an cAACMe(Bneop)(4-Me-C6H4) (BCA4) belegen die Reversibilitat dieser oxidativen Addition am Kohlenstoffatom.

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