Synthesis of Benzofulvene Derivatives from Diarylacetylenes via Pd(II)-Catalyzed Alkyne-Directed C(sp²)–H Bond Activation

Abstract

A novel and efficient protocol for the synthesis of benzofulvene derivatives from easily available diarylacetylenes has been developed. The reaction proceeds through rarely reported carboxylate-assisted alkyne-directed ortho-C(sp(2))-H palladation followed by insertion of another diarylacetylene.

Synthesis of Benzofulvenes via Cp*Co(III)-Catalyzed C–H Activation and Carbocyclization of Aromatic Ketones with Internal Alkynes

“…GC-MS analysis of the reaction mixture did show the presence of 1,2-diphenylethanone. It should be mentioned that Hua and Chuang have also reported the synthesis of benzofulvenes from two arylacetylenes via Pd-catalysis.…”

C–H Activation and Alkyne Annulation via Automatic or Intrinsic Directing Groups: Towards High Step Economy

“…Though reactions using alkyne DG is much less designable than those using other DGs, related side reactions were occasionally found when alkynes were employed as coupling partners for C–H functionalization, which led us to develop new synthetic methods. In 2015, we disclosed a dimerization reaction of diarylacetylenes to afford multisubstituted benzofulvenes, in which alkyne served as an DG in for ortho ‐C–H palladation under assistant by carboxylate additives (Scheme ) . The C–H activation was irreversible, as no scrambling of ortho ‐deuterium was observed.…”

Catalytic Dimerization of Alkynes via C–H Bond Cleavage by a Platinum–Silylene Complex

“…The scope of the platinum–silylene-catalyzed cyclodimerization of diphenylacetylene derivatives was next investigated (Table ). Substrates bearing electron-donating groups, such as methyl ( 1b ) or methoxy groups ( 1c ), were applicable to this reaction, although the yields were relatively low compared with that for electron-neutral alkyne 1a because of the formation of indene derivative 3 as a byproduct. In contrast, electron-deficient alkynes, such as that bearing trifluoromethyl groups ( 1d ), were efficiently cyclodimerized without the formation of an indene-type byproduct.…”

“…First, ligand exchange between dvtms and two alkynes forms Pt­(alkyne) 2 complex A . The ortho C–H bond of alkyne 1a then oxidatively adds to the platinum center, with an alkyne serving as an ortho directing group, ,, to provide Pt­(II) hydride intermediate B . The insertion of a second alkyne into the aryl–platinum bond forms alkenylplatinum complex C , which leads to the formation of seven-membered platinacycle D via intramolecular trans hydrometalation .…”