Reaction of Ethyl Diazoacetate with Alkyl-Aromatic Substrates: Influence of the TpxCu Catalyst in the Addition versus Insertion Chemoselectivity (Tpx = Homoscorpionate)

The complexes Tp Br3 Cu(NCMe) ( 1 ) and Tp Ms Cu ( 2 ) catalyze the addition of the:CHCO 2 Et unit (generated from N 2 CHCO 2 Et, EDA) to benzene to give a cycloheptatriene ring, in analogy with the Büchner reaction. When alkyl groups are attached to the aromatic rings, the selectivity of the reaction can be oriented toward addition or, alternatively, to the insertion into an alkyl C−H bond by using 1 or 2, respectively.