Reaction of Ethyl Diazoacetate with Alkyl-Aromatic Substrates:  Influence of the Tp^xCu Catalyst in the Addition versus Insertion Chemoselectivity (Tp^x = Homoscorpionate)

Abstract

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 Bu ¨chner 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.

Copper, silver and gold-based catalysts for carbene addition or insertion reactions

“…(4)). We also found that the ratio of addition:insertion was affected by the nature of the Tp x ligand (Table 7) [21]. The reaction of EDA and furan in the presence of dirhodium tetraacetate, followed by addition of elemental iodine, has been employed for years as a route for the formation of dienes (Eq.…”

Gold-catalyzed naphthalene functionalization

“…Thus, the reaction of ethyl diazoacetate (EDA) with benzene in the presence of such catalysts at room temperature exclusively affords the cycloheptatriene product in quantitative yields. The reaction, always referred to the intermolecular version, was later observed with other metal-based catalysts [4–6]. …”

The Effect of Catalyst Loading in Copper‐Catalyzed Cyclohexane Functionalization by Carbene Insertion

“…In the case of copper, the first observation of one of these species under catalytic conditions is due to Straub and Hofmann. [5] Later, Warren and Dai described the preparation and structural characteriza- [ [6] In recent years we have described the potential of a family of complexes of general formula [Tp x Cu(NCMe)] (Tp x = homoscorpionate ligand) toward the two processes mentioned above: the addition of :CHCO 2 Et from ethyl diazoacetate (EDA) to multiple carbon-carbon bonds (alkenes, [7] alkynes, [8] aromatics [9] ) or its insertion into single X-H bonds (alkanes, [10] amines, [11] alcohols [12] ). All these transformations are accompanied by the copper-catalyzed carbene coupling reaction, which leads to the formation of diethyl fumarate and maleate in variable yields [Equation (1)].…”