Silver-Catalyzed C-C Bond Formation Between Methane and Ethyl Diazoacetate in Supercritical CO ₂

Abstract

The use of methane, the lightest hydrocarbon and primary component of natural gas, as a source for fine chemicals production remains an appealing goal on scientific, economic and environmental grounds (1-4). Transition metal catalyzed C-H bond activation is a promising approach to achieve functionalization of the strong and relatively inert C-H bonds of alkanes more generally. In one possible scenario, these reactions proceed by metal-promoted C-H bond oxidative cleavage followed by insertion of a suitable X group into the M-C bond and release of the functionalized product by means of reductive elimination of the C-X-H unit (5). Individual reaction steps for this and related catalytic cycles have been widely reported (6), but a major challenge has been that removal of the functionalized fragments from the metal coordination sphere is often unfavorable, due to the robustness of the M-C bonds. Only FINAL VERSION ACCEPTED

Catalytic Functionalization of Methane and Light Alkanes in Supercritical Carbon Dioxide

“…Ethyl propionate and butyrate were obtained leading to a corrected relative reactivity CÀH ethane /CÀ H methane of 14. [21] On the basis of the available data, we believe that the homogeneous nature of this transformation is well established.…”

“…Substrates and solvents were rigorously dried prior to their use. The complexes [Ag-(acetone)(F 21 -Tp 4Bo,3CF3 )] (1), [27] [Ag(F 27 -Tp 4Bo,3CF2CF3 )(thf)] (2), [21] [Ag-(acetone)(F 33 -Tp 4Bo,3(CF2)2CF3 )] (3), [22] [Ag(acetone)(F 39 -Tp 4Bo,3(CF2)3CF3 )] (4) [22] and [Ag(acetone)(F 51 -Tp…”

Mechanistic Elucidation of the Arylation of Non-Spectator N-Heterocyclic Carbenes at Copper Using a Combined Experimental and Computational Approach

“…As the direct reaction of Cu I -NHC with iodobenzene to give arylated products is feasible (reactivity order 8 > 7 >> 9), density functional theory (DFT) was used to understand potential reaction pathways for this process. The first pathway considered was a carbene insertion mechanism (via I, Scheme 5), akin to that reported by Pérez et al 36 A second pathway involves a Cu …”

Silver-Mediated Direct sp3 C–H Bond Functionalization

“…In 2011, Asensio, Etienne, Pérez, and coworkers reported a first example of carbene insertion into methane sp 3 C-H bond by silver catalysts (Scheme 4) [22]. The reaction was performed using Tp X Ag (silver complexes 2, 3, 4) as the catalysts and ethyl diazoacetate as a carbene source.…”