On the Mechanism and Stereoselectivity of the Copper(I)-Catalyzed Cyclopropanation of Olefins − A Combined Experimental and Density Functional Study

Abstract

The mechanism of copper(I)-catalyzed olefin cyclopropanation with diazomethanes has been studied at the BP86/AE1 level of density-functional theory. For the model system Cu(diazabutadiene) + + ethene + diazomethane, copper carbene complexes are confirmed as viable intermediates, with rate-determining barriers of the order of 25 kcal/mol (energies including zero-point corrections) or 14 kcal/mol (when entropic contributions are included). For another model system, Cu(2,9-dimethyl-1,10-phenanthroline) + + styrene + diazoacetate, very small anti/syn selectivities (resulting in trans/cis-cyclopropanes) have been found both computationally and experimentally. Cu(carbene) complexes with

Synthesis of DEFG ring system of cneorins

“…10 Some mechanistic studies of the intermolecular copper(I)-catalyzed cyclopropanations have also been published. [12][13][14] The intramolecular cyclopropanation of diazomalonates of type A in Scheme 2 (a 1,1-disubstituted olefin) is unprecedented in the literature, although there are earlier examples of both 1,2-disubstituted and even 1,2,2-trisubstituted olefins being cyclopropanated with copper catalysts. 8 Scheme 2.…”

Synthesis of DEFG ring system of cneorins

“…10 Some mechanistic studies of the intermolecular copper(I)-catalyzed cyclopropanations have also been published. [12][13][14] The intramolecular cyclopropanation of diazomalonates of type A in Scheme 2 (a 1,1-disubstituted olefin) is unprecedented in the literature, although there are earlier examples of both 1,2-disubstituted and even 1,2,2-trisubstituted olefins being cyclopropanated with copper catalysts. 8 Scheme 2.…”

Coinage metal carbenes in heterocyclic synthesis via formation of new carbon-heteroatom bonds

“…[33][34][35] The mechanism of the copper(I) promoted activation of diazo compounds has been studied by DFT (Scheme 2). [36][37][38] The rate-determining step has been often proposed to be the complexation of the diazo compound (step a), which occurs by coordination of the negatively polarized carbon of the diazo substrate to the Lewis acidic free copper and can be in competition with other Lewis bases that can potentially slow or even halt copper catalysis by blocking the crucial substrate binding. Kinetic data reported fit with a dissociative ligand exchange mechanism.…”

Concave Reagents 36: Transition Metal Complexes With Concave 1,10-phenanthrolines

“……”

Synthesis of DEFG ring system of cneorins

“…10 Some mechanistic studies of the intermolecular copper(I)-catalyzed cyclopropanations have also been published. [12][13][14] The intramolecular cyclopropanation of diazomalonates of type A in Scheme 2 (a 1,1-disubstituted olefin) is unprecedented in the literature, although there are earlier examples of both 1,2-disubstituted and even 1,2,2-trisubstituted olefins being cyclopropanated with copper catalysts. 8 Scheme 2.…”

Coinage metal carbenes in heterocyclic synthesis via formation of new carbon-heteroatom bonds

“…[33][34][35] The mechanism of the copper(I) promoted activation of diazo compounds has been studied by DFT (Scheme 2). [36][37][38] The rate-determining step has been often proposed to be the complexation of the diazo compound (step a), which occurs by coordination of the negatively polarized carbon of the diazo substrate to the Lewis acidic free copper and can be in competition with other Lewis bases that can potentially slow or even halt copper catalysis by blocking the crucial substrate binding. Kinetic data reported fit with a dissociative ligand exchange mechanism.…”

Concave Reagents 36: Transition Metal Complexes With Concave 1,10-phenanthrolines

“……”

Synthesis of DEFG ring system of cneorins

“…10 Some mechanistic studies of the intermolecular copper(I)-catalyzed cyclopropanations have also been published. [12][13][14] The intramolecular cyclopropanation of diazomalonates of type A in Scheme 2 (a 1,1-disubstituted olefin) is unprecedented in the literature, although there are earlier examples of both 1,2-disubstituted and even 1,2,2-trisubstituted olefins being cyclopropanated with copper catalysts. 8 Scheme 2.…”

Coinage metal carbenes in heterocyclic synthesis via formation of new carbon-heteroatom bonds

“…[33][34][35] The mechanism of the copper(I) promoted activation of diazo compounds has been studied by DFT (Scheme 2). [36][37][38] The rate-determining step has been often proposed to be the complexation of the diazo compound (step a), which occurs by coordination of the negatively polarized carbon of the diazo substrate to the Lewis acidic free copper and can be in competition with other Lewis bases that can potentially slow or even halt copper catalysis by blocking the crucial substrate binding. Kinetic data reported fit with a dissociative ligand exchange mechanism.…”

Concave Reagents 36: Transition Metal Complexes With Concave 1,10-phenanthrolines

“……”