Palladium-Catalyzed Regioselective Alkynylation of Pyrroles and Azoles under Mild Conditions: Application to the Synthesis of a Dopamine D-4 Receptor Agonist
摘要:
A mild and general method for the direct alkynylation of azoles such as pyrrole, indole, and 7-azaindole is described here. Using a simple catalytic system such as Pd(OAc)(2) (2.5 mol %), P(tBu)(2)Me center dot HBF4 (5 mol %), and NaOAc (2 equiv) allowed the regioselective introduction of various alkynyl residues at the C-2 position of pyrroles. Interestingly, C-2 alkynylation was also observed on C-3-substituted indoles, whereas classical C-3 alkynylation was obtained on selected unsubstituted indoles and 7-azaindole. Our methodology has been illustrated by the efficient synthesis of a potential schizophrenia drug (dopamine D-4 inhibitor).
Ultrasound-promoted intramolecular direct arylation in a capillary flow microreactor
作者:Lei Zhang、Mei Geng、Peng Teng、Dan Zhao、Xi Lu、Jian-Xin Li
DOI:10.1016/j.ultsonch.2011.07.008
日期:2012.3
An intramoleculardirectarylation of various aryl bromides was performed using ultrasonic irradiation and a continuous flow capillary microreactor. The present procedure provided a higher functional group tolerance, ligand-free, milder reaction conditions and a shorter reaction time for the directarylation compared with the conventional methods. The ultrasonic irritation not only greatly promoted
A case of chain propagation: α-aminoalkyl radicals as initiators for aryl radical chemistry
作者:Timothée Constantin、Fabio Juliá、Nadeem S. Sheikh、Daniele Leonori
DOI:10.1039/d0sc04387g
日期:——
The generation of aryl radicals from the corresponding halides by redox chemistry is generally considered a difficult task due to their highly negative reduction potentials. Here we demonstrate that α-aminoalkyl radicals can be used as both initiators and chain-carriers for the radical coupling of aryl halides with pyrrole derivatives, a transformation often employed to evaluate new highly reducing
Pd-catalyzed C-H annulation reactions of halo- and aryl-heteroarenes were developed using readily available o-bromobiaryls and o-dibromoaryls, respectively. A variety of five-membered heteroarenes rapidly provided the corresponding phenanthrene-fused heteroarenes, which led to the identification of phenanthro-pyrazole and thiazole as new, stable -2 V redox couples. The flexible syntheses and tunability
Palladium-Catalyzed Decarboxylative Cross-Coupling Reaction Between Heteroaromatic Carboxylic Acids and Aryl Halides
作者:François Bilodeau、Marie-Christine Brochu、Nicolas Guimond、Kris H. Thesen、Pat Forgione
DOI:10.1021/jo9022793
日期:2010.3.5
A full overview of the decarboxylative cross-coupling reaction between heteroaromatic carboxylic acids and aryl halides is described. This transformation employs palladium catalysts with short reaction times providing facile synthesis of aryl-substituted heteroaromatics. The effect of each reaction parameter including solvent, base, and additive employed as well as the full substrate scope of this
Isoindolo[2,1-a]indol-6-one—a new pyrolytic synthesis and some unexpected chemical properties
作者:Lynne A. Crawford、Nathan C. Clemence、Hamish McNab、Richard G. Tyas
DOI:10.1039/b802273a
日期:——
Isoindolo[2,1-a]indol-6-one 1 is formed by a sigmatropic shift-elimination-cyclisation cascade by flash vacuum pyrolysis (FVP) of methyl 2-(indol-1-yl)benzoate 7 at 950 degrees C. The dihydro compound 16 is easily obtained by catalytic reduction of 1, but the reaction is very sensitive to steric effects at the 11-position. Attempted ring-opening of 1 in basic methanol provides an equilibrium of isoindolo[2