Coupling reactions with haloaromatic amines and alcohols for a practical synthetic route to 2-substituted aminophenyl and hydroxyphenyl pyridines

5-Substituted-2-furaldehydes: A Synthetic Protocol Utilizing an Organozinc Route

“…We then attempted the coupling reaction with haloaromatic compounds containing a hydroxyl or an amino functional group that would be more challenging. Even though there are very limited examples of coupling reactions of organozinc compounds with haloaromatic alcohols and amines, to our best knowledge no report revealed the coupling reaction with furanylzinc bromide. In our study, the coupling reaction was easily accomplished using 2 mol % Pd(OAc) 2 and 4 mol % SPhos in THF at room temperature.…”

“…To magnify the scope of our methodology, special heteroarylzinc reagents, pyridylzinc halides was chosen and employed in the coupling reaction with 5-bromo-2-furaldehyde since 5-pyridyl-2-furaldehydes have been frequently used for synthetic intermediates in pharmaceuticals . The pyridylzinc halides used in this study were also easily prepared by the direct oxidative addition of active zinc to the corresponding halides . As summarized in Table , the coupling reactions were carried out under the same reaction conditions as used in the previous study (a catalytic amount of Pd[P(Ph 3 )] 4 at room temperature in THF).…”

Structure–activity relationship studies of SEN12333 analogues: Determination of the optimal requirements for binding affinities at α7 nAChRs through incorporation of known structural motifs

“…The layers were separated, and the aqueous layer was extracted with dichloromethane (2 Â 50 mL), the organic extracts were combined, dried (MgSO 4 ), filtered, and evaporated in vacuo. Purification by flash chromatography on silica eluting with hexane-ethyl acetate (1:1) gave compound 52 (0.22 g, 27%) as a yellow solid; mp 131e133 C (lit mp 131e132 C); n max /cm À1 (53) [64,65]. A solution of compound 52 (0.2 g, 1.03 mmol) in methanol (10 mL) was treated with 10% palladium on carbon (20 mg) and subjected to a hydrogen atmosphere.…”

Palladium-catalyzed direct arylation of pyridine N-oxide with 2-bromoacetanilides. Synthesis of benzisoxazolo[2,3-a]pyridinium tetrafluoroborates

“…13 These compounds were prepared either by reduction of the corresponding 2-(2-nitroaryl)pyridine (prepared by reaction of pyridine with an o -nitroaryldiazonium salt 14,15 ), by palladium-catalyzed cross-coupling of a (2-aminophenyl)boronate ester with a 2-halopyridine, 16 or by palladium-catalyzed coupling of 2-pyridylzinc bromide with a 2-haloaniline. 17 Since many of these existing methods suffer from low yields or limited scope, we decided to explore the palladium-catalyzed direct arylation of pyridine N -oxide ( 2 ) with an appropriate 2-bromoacetanilide ( 3 ) using the method developed by Fagnou. 18,19 Although this protocol had not yet been applied using 2-bromoacetanilides as coupling partners, we believed it would provide a simple route to a wide variety of acetylated 2-(2-aminoaryl)pyridine N -oxides ( 4 ).…”