A Suzuki Coupling Based Route to 2,2‘-Bis(2-indenyl)biphenyl Derivatives

Abstract

Because of the promising performance in olefin polymerization of 2,2'-bis(2-indenyldiyl)biphenyl zirconium dichloride, we developed a new and broadly applicable route to 2,2'-bis(2-indenyl)biphenyl derivatives. Reaction of the known 2,2'-diiodobiphenyl (26) with the new 2-indenyl boronic acid (23) did not result in the desired 2,2'-bis(2-indenyl)biphenyl (10); instead an isomer thereof, (spiro-1,1-(2,2'-biphenyl)-2-(2-indenyl)indane) (27), was obtained. It was found that compound 10 could be made via a palladium-catalyzed reaction of 2,2-biphenyldiboronic acid (31) with 2-bromoindene (21) under standard Suzuki reaction conditions. However, the yield of this reaction was low at low palladium catalyst loadings, due to a competitive hydrolysis reaction of 2,2-biphenyldiboronic acid (31). HTE techniques were used to find an economically viable protocol. Thus, use of the commercially available 1.0 molar solution of (n-Bu)(4)NOH in methanol with cosolvent toluene led to precipitation of the pure product in a fast and clean reaction, using only 0.7 mol % (0.35 mol % per C-C) of the expensive palladium catalyst.

On the Development of Titanium κ1‐Amidinate Complexes, Commercialized as Keltan ACE™ Technology, Enabling the Production of an Unprecedented Large Variety of EPDM Polymer Structures

“…The substituted monocyclopentadienyl, k1‐amidinato titanium dichloride catalyst precursors are synthesized by reacting the neutral amidine ligand with titanium trichloride complexes of Cp ( 1 ), pentamethylcyclopentadienyl ( 2 ), or tert ‐butylcyclopentadienyl ( 3 ) in the presence of 4 equiv of triethylamine in toluene at 50 °C (Scheme ) . The reaction proceeds for 16 h and yields the desired and highly pure titanium dichloride complexes in good yields, using crystallization method in toluene and hexane for the purification step.…”

Synthesis of Aryl- and Heteroaryl-Substituted Cyclopentadienes and Indenes and their Use in Transition Metal Chemistry

“…Halterman and co-workers prepared in situ the chlorozinc indenide 74 which was coupled in the presence of 1.2 % of Pd(PPh 3 ) 4 with o-, m-or p-dihalobenzenes to afford Suzuki coupling can also be used for the introduction of arylsubstituents into indenes. Ijpeij et al showed that 2-indenyl boronic acid can be coupled with aryl triflates or aryl iodides [63]. However, depending on the leaving group X (X = OTf, I) monosubstituted indenes 78 or undesired compounds like 79 are the main products (Fig.…”

“…The biphenylene bridged bis-indene 81 was obtained by this procedure in 79% isolated yield (Fig. 34) [63].…”

R&D Intensification in Polymer Catalyst and Product Development by Using High‐Throughput Experimentation and Simulation

“…An illustrative example of a ligand synthesis route optimization was also reported (Scheme 2). [3] Starting point before the HT optimization was the reaction of the diboronic acid with 2 equivalents of 2-bromoindene in dimethoxyethane (DME)/water with K 2 CO 3 as the base under catalysis of 7 mol-% Pd(PPh 3 ) 4 . This resulted in the formation of the desired ansa metallocene ligand, which was isolated after crystallization from ethanol/ acetone in 79% yield.…”