A Gold Catalyst for Carbene‐Transfer Reactions from Ethyl Diazoacetate

Abstract

The use of transition-metal-based catalysts for the transfer of carbene units from diazo compounds constitutes a powerful tool in organic synthesis.[1] Several metals have been reported to mediate this transformation effectively, and the appropriate selection of ligands has permitted excellent selectivities. Highly chemo-, diastereo-, and/or enantioselective systems have been reported with rhodium-, copper-, or cobaltcontaining catalysts. In fact, nearly all 12 elements of Groups 8-11 have been found to decompose diazo compounds and transfer a carbene unit to saturated or unsaturated organic substrates, [2] leading to the insertion or addition product, respectively (Scheme 1). Only one of these 12 elements remains unexplored in this chemistry: gold. [3] Although the other members of Group 11-copper and, to a lesser extent, silver-have been described to induce such transformations, conducting this type of catalytic reaction with gold remains a challenge. We therefore focused our attention on the development of a gold-based catalyst, as a result of our experience in the area of metal-catalyzed carbene transfer from ethyl diazoacetate (EDA). [4] We recently reported the catalytic behavior of [(IPr)CuCl] (1, IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene) for the transfer of carbene from ethyl diazoacetate to olefins, amines, and alcohols to form cyclopropanes, amino acid derivatives, and ethers, respectively.[5]

Synthesis and characterisation of Au(I)-(ITent) complexes

“…As observed for the Pd complexes, [4a] all members of the ITent family provided greater coverage than IPr, [9] with some even exceeding the steric bulk of IPr*. [10] The crystal obtained for [AuCl(IPent)] also showed two possible conformations with different buried volumes, [4b] highlighting its ability to adapt to incoming and outgoing substrates.…”

Synthesis and coordination compounds of a bis(imino)acenaphthene (BIAN)-supported N-heterocyclic carbene

“…While no attempt has been made here to review the merits of the various approaches, we opted to use the recently proposed method of Nolan et al 12 2 Cl complexes. 11 The computed TEP value of 2042 cm -1 for 2 suggests that it is a relatively strong donor. Unfortunately, despite several attempts, it was not possible to record the 13 C chemical shift for the carbenic carbon of 2 due to low solubility and relaxation effects.…”

Gold(I) Carbenoids: On‐Demand Access to Gold(I) Carbenes in Solution

“…This process closely resembles the gold-catalyzed cyclopropanation of olefins with diazo compounds. [23] Thus,complexes 1a and 1c could methylenate cyclohexene and norbornene,yielding norcarene 4a and exotricyclo[3.2.1.0 2,4 ]octane 4b in moderate to good yields when activated with either as ilver salt or aT MS reagent (Table 2, entries 1a,b-4a,b). Phosphite complex 1d could only generate traces of cyclopropanes with cyclohexene (Table 2, entries5a,b and 6a,b).…”