This perspective reports on some of the main copper-catalyzed routes to the construction of the pyrrole and furan rings incorporated into the indole and benzobfuran systems, respectively. The first ...part illustrates the synthesis of indoles through cyclizations of 2-alkynylanilid(n)es, preformed or generated in situ, and cyclizations via intramolecular N-arylation, N-vinylation, and C-C bond forming reactions. The second part illustrates the synthesis of benzobfurans through cyclizations of preformed 2-alkynylphenols, domino synthesis of 2-alkynylphenols/cyclization processes, and cyclizations via intramolecular O-arylation reactions.
A gold-catalyzed protocol to obtain functionalized 3H-pyrrolo 1,2,3-de quinoxalines from suitable substituted N-alkynyl indoles has been proposed. The mild reaction conditions were revealed to be ...compatible with different functional groups, including halogen, alkoxyl, cyano, ketone, and ester, allowing the isolation of title compounds with yields from good to high. A reaction mechanism has been proposed, and theoretical calculations have been provided to rationalize the final step of the hypothesized reaction mechanism. As quinoxaline-containing polycyclic compounds, this class of molecules may represent a valuable template in medicinal chemistry and material science.
Antibiotic resistance is now considered a worldwide problem that puts public health at risk. The onset of bacterial strains resistant to conventional antibiotics and the scarcity of new drugs have ...prompted scientific research to re-evaluate natural products as molecules with high biological and chemical potential. A class of natural compounds of significant importance is represented by alkaloids derived from higher plants. In this review, we have collected data obtained from various research groups on the antimicrobial activities of these alkaloids against conventional antibiotic-resistant strains. In addition, the structure-function relationship was described and commented on, highlighting the high potential of alkaloids as antimicrobials.
Sonogashira Cross-Coupling of Arenediazonium Salts Fabrizi, Giancarlo; Goggiamani, Antonella; Sferrazza, Alessio ...
Angewandte Chemie (International ed.),
June 1, 2010, Letnik:
49, Številka:
24
Journal Article
Recenzirano
Star‐crossed lovers: The domino iododediazoniation/Sonogashira cross‐coupling of terminal alkynes with arenediazonium salts has been developed. The arenediazonium salt ...synthesis/iododediazoniation/Sonogashira cross‐coupling sequence can also be performed as a one‐pot process, omitting the isolation of the arenediazonium salt.
The gold-catalyzed cyclization of 2,2-bis(3-arylprop-2-yn1-yl)malonic acid has been proposed as an efficient approach to substituted 3,8-dibenzyl-2,7-dioxaspiro4.4nonane-1,6-diones. The reaction ...proceeds smoothly in mild reaction conditions to give the desired products in quantitative yields in the presence of variously substituted starting materials. In addition, the synthesis of γ-arylidene spirobislactone bearing different substituents on the two aromatic rings has been achieved. This kind of compound could be of great interest in pharmaceutical science given the widespread presence of this scaffold in bioactive natural and synthetic products.
An alternative Au(I)-catalyzed synthetic route to functionalized 1,2-dihydroquinolines is reported. This novel approach is based on the use of N-ethoxycarbonyl protected-N-propargylanilines as ...building blocks that rapidly undergo the IMHA reaction affording the 6-endo cyclization product in good to high yields. In the presence of N-ethoxycarbonyl-N-propargyl-meta-substituted anilines, the regiodivergent cyclization at the ortho-/para-position is achieved by the means of catalyst fine tuning.
An efficient strategy for the synthesis of 6-unsubstituted indolo1,2-
quinazolines is described. The Pd-catalyzed reaction of
-(
-aminophenylethynyl) trifluoroacetanilides with Ar-B(OH)
afforded 2-(
...-aminophenyl)-3-arylindoles, that were converted to 12-arylindolo1,2-
quinazolines by adding dimethylformamide dimethyl acetal (DMFDMA) to the reaction mixture after extractive work-up. This reaction outcome is different from the previously reported Pd-catalyzed sequential reaction of the same substrates with Ar-I, Ar-Br and ArN
BF
, that afforded 12-arylindolo1,2-
quinazolin-6(5
)-ones. Moreover, 12-unsubstituted indolo1,2-
quinazolines can be obtained both by reacting 2-(
-aminophenyl)indoles with DMFDMA or by sequential Pd-catalyzed reaction of
-(
-aminophenylethynyl)aniline with DMFDMA.
The scope and the generality of gold versus silver catalyzed intramolecular hydroarylation reactions of 3-(3-arylprop-2-ynyl)oxybenzene derivatives in terms of rings substitution were investigated. ...Only products deriving from 6-endo cyclization were exclusively formed. The features of substituents had a considerable effect on the reaction outcome in the presence of silver catalysis, whereas gold catalysis revealed a unique blend of reactivity and selectivity and represented the only choice for the intramolecular hydroarylation reaction of the starting substrates bearing electron deficient arenes.
Full details as well as the study of the scope, limitations, and further elaboration of a straightforward approach to the synthesis of 2,5,7-trisubstituted benzobfurans from 2-bromo- and ...2-chloro-6-iodo-4-substituted phenols through a consecutive copper- and/or palladium-catalyzed assembly and functionalization process is described. Functionalization at the C(7) position is carried out by Suzuki–Miyaura cross-coupling, alkynylation, alkenylation, and C–N bond forming reactions. A one-pot protocol for the synthesis of 2,5,7-trisubstituted benzobfurans is also reported.
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A straightforward assembly of polysubstituted 1,2-dihydro-3H-pyrrolo1,2-aindol-3-ones through a domino palladium-catalyzed reaction of indol-2-ylmethyl acetates with 1,3-dicarbonyl derivatives is ...described. The key role of the features of the 1,3-dicarbonyls on the reaction outcome has been explored. The employment of 2-methylcyclohexan-1,3-dione as the dicarbonyl source could allow further challenging indole nucleus functionalizations.
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