Gold(I)‐Catalyzed Intramolecular C(sp³)−H Insertion by Decarbenation of Cycloheptatrienes

Abstract

An ovel synthesis of indanes and dihydronaphtalenes based on the intramolecular insertion into C(sp 3 )ÀH bonds of gold(I) carbenes generated by retro-Buchner reaction (decarbenation) has been developed.D euterium-labeling and kinetic isotope effect experiments, DFT calculations, and generation of the proposed carbene intermediate from aw ell-characterized gold(I)c arbenoid support the involvement of at hree-center concerted mechanism for the C(sp 3 )À Hf unctionalization process.

Buchwald‐Type Ligands on Gold(I) Catalysis

“…Finally, gold(I)‐carbenes generated by retro‐ Buchner reaction also undergo C(sp 3 )−H insertion to give substituted indanes 73 and 3‐aryl‐1,2‐dihydronaphtalenes 74 from 71 and 72 , respectively. In these transformations, cationic NHCgold(I)‐complex were found to be superior catalysts …”

Site-Selective C–H Benzylation of Alkanes with N-Triftosylhydrazones Leading to Alkyl Aromatics

“…Although advances have been made in C(sp 2 )-H alkylation by donor-carbenes, [40][41][42] insertions into C(sp 3 )-H bonds have been restricted to intramolecular versions. [43][44][45][46][47] Intermolecular insertions are more challenging as donor carbenes are typically not sufficiently reactive to undergo effective reaction, 14,15 and are instead more prone to undergo dimerization (especially compared to acceptor-stabilized carbenes). [48][49][50][51] Furthermore, insertion into the C-H bonds of the alkane substrate is less electronically favored than the benzylic C-H bonds of the insertion products, 52 which usually leads to undesirable over-insertion.…”

Recent advances in transition-metal-catalyzed carbene insertion to C–H bonds

“…152 A strategy to place the alkyl C-H bond closer to the reactive gold(I) center was used to render such an intramolecular C-H functionalization process (Scheme 25). 153 In the presence of 5 mol% (IPr)Au(NCPh) in dichloroethane (DCE) at 100 1C, 7-(2tert-butyl)phenylcyclohepta-1,3,5-trienes (41) reacted to form the target products 42 in 74-90% yields (eqn (12)). However, an adjacent oxygen atom did not benefit the transformation (eqn ( 13)).…”