Studies on Suzuki Coupling Reactions of Large Sterically Hindered Substrates

Abstract

Suzuki coupling reaction of 2-(Trifluormethoxy) phenylboronic acid with 2-bromo-1,3-dichloro-5-nitrobenzene were successfully conducted by using Pd2(dba)3 as the catalyst and in satisfactory to good yields. The 4-(2-(diphenylphosphino)phenyl) morpholine was the best ligand in this reaction. Biaryl amides 8t which gained much attention in the pharmaceutical industry because of using as RORγt inhibitors could be synthesized using the product of Suzuki reaction 3a as the substrate after 2 steps. Higher yield of 8t could be got by using this method than the previous work.

Microwave-Assisted Regioselective Suzuki Coupling of 2,4-Dichloropyrimidines with Aryl and Heteroaryl Boronic Acids

“…In a continuation of our study, we screened the most common commercially available palladium catalysts for this type of reaction. Tris(dibenzylideneacetone)palladium(0) (Pd 2 dba 3 ) was not efficient for this type of reaction as has already been observed [32,33], whereas as an adduct with chloroform (Pd 2 dba 3 • CHCl 3 ) and together with tri-tertbutylphosphonium tetrafluoroborate (TTBP • HBF 4 ) as a ligand it gave 35% and 23% yield, respectively (Table 2, entries 1-3). With bis(triphenylphosphine)palladium(II) chloride (PdCl 2 (PPh 3 ) 2 ) similarly low yield of 36% was achieved (Table 2, entry 4).…”

“…In a continuation of our study, we screened the most common commercially available palladium catalysts for this type of reaction. Tris(dibenzylideneacetone)palladium(0) (Pd2dba3) was not efficient for this type of reaction as has already been observed [32,33], Scheme 1. Suzuki coupling of 2,4-dichloropyrimidine (1) with phenylboronic acid (2) as our model reaction.…”