Copper Pincer Complexes as Advantageous Catalysts for the Heteroannulation of ortho‐Halophenols and Alkynes

Abstract

A new, non-symmetrical copper(II) pincer complex catalyzes much more efficiently the formation of benzofuran by the reaction between ortho-iodophenols and alkynes. The lowest catalyst loadings are realized for this reaction, and bromo-and chlorophenols are heteroannulated for the first time. Strong evidence for hydrophenoxylation and intra-molecular halogen atom-transfer steps catalyzed by this remarkably active, recyclable homogeneous catalyst is provided.

Synthesis, Characterization, and Catalytic Application of Mononuclear and Dendritic Cationic CuI Iminopyridine‐Ligated Complexes in Aryl Iodide Hydroxylation

“…First, we investigated whether the iminopyridine Cu I complexes serve as a reservoir of copper nanoparticles or whether a heterogeneous active species is formed during the reaction. This was accomplished by performing the hydroxylation reaction in the presence of additives that are known to poison and deactivate copper nanoparticles (Scheme ) …”

“…This stabilizing effect has been observed previously. [7c] Decreasing the reaction time to 1 hour allowed us to investigate the effect of the metallodendrimer and dendrimer generation on catalysis in more detail (Table 3, entries [19][20][21][22][23][24][25][26]. For the G1 metallodendrimers the observed catalytic activity decreases in the order DC2 > DC3 > DC1 > DC4.…”

The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2014

“…467) for total synthesis of aspeverin [896]: (3) transformation of the polyether aldehyde 468 to the corresponding alkene 469 through Tebbe olefination for synthesis of a simplified maitotoxin [897]; (4) methylenation of aryl acetates using the Tebbe reagent for the preparation of benzofurans [898]; (5) methylenation of benzopyranones using the Tebbe reagent for the preparation BACE1 inhibitors [899]; and (6) one-pot conversion of succinic anhydrides (e.g. 470) to 2,5-dimethylpyrroles (e.g.…”

New Copper, Palladium and Nickel Catalytic Systems: An Evolution towards More Efficient Procedures

“…Our protocol was then applied to a number of iodophenols, 2‐iodopyridin‐3‐ol, and arylacetylenes to provide the corresponding 2‐arylfuran derivatives in good to excellent yields. Moreover, this exceptionally active system was also successfully applied to the unprecedented copper‐catalysed heteroannulation with o ‐bromo‐ and o ‐chlorophenols, and alkyl or alkenylacetylenes were also regioselectively coupled (Figure ) 37…”