Multicomponent synthesis of 4-aminophthalazin-1(2H)-ones by palladium-catalyzed isocyanide insertion

Copper-catalysed dehydrogenative self-coupling/cyclization of 5-aminopyrazoles: synthesis and photophysical study of pyridazines

An interesting self-coupling/cyclization of 5-aminopyrazoles is revealed, which provides a variety of pyridazine cores in reasonable yields. In this reaction, C(sp²)-C(sp²) and N-N bond formation occurs simultaneously in one reaction vessel. The photophysical properties of the synthesized compounds were also studied and some of them exhibited fluorescence properties with good quantum yields. A radical mediated reaction mechanism is proposed with the help of control experiments.

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

Amino- and polyaminophthalazinones were synthesized by the palladium‐catalyzed amination (alkyl- and arylamines, polyamines) of 4-bromophthalazinones in good yields. The coordinating properties of selected aminophthalazinones towards Cu(II) ions were investigated and the participation of the nitrogen atoms in the complexation of the metal ion was shown. A biological screening of the potential cytotoxicity of selected synthesized compounds on HT-29 and PC-3 cell lines, as well as on the L-929 cell line, proved that some amino derivatives of phthalazinone show interesting anticancer activities. The detailed synthesis, spectroscopic data, and biological assays are reported.

Palladium-catalyzed multicomponent reactions: an overview

This first review on this topic focuses on the developments in the chemistry of Pd-catalyzed multi-component reactions (MCRs). MCRs are generally atom economic, ideal and eco-friendly reactions, and often the final products are generated almost without any by-products. In this review, the developments in Pd-catalyzed MCRs are categorized based on the products formed such as acyclic compounds, carbocyclic compounds, heterocyclic compounds and miscellaneous compounds. MCRs have great applications in various fields like medicinal chemistry, combinatorial synthesis, heterocyclic chemistry etc. and this review covers the literature up to 2019.

Palladium-Catalyzed Construction of Amidines from Arylboronic Acids under Oxidative Conditions

A valuable palladium-catalyzed three-component coupling reaction for the synthesis of amidines has been developed. Using arylboronic acids, isocyanides, and anilines as the reactants under oxidative conditions, various amidines were isolated in good yields with good functional group tolerances.

Regioselective Synthesis of Substituted 4-Alkylamino and 4-Arylaminophthalazin-1(2H)-ones

An efficient regioselective synthesis of substituted 4-alkylamino and 4-arylaminophthalazin-1(1H)-ones 5 is described. This new method features the formation of substituted phthalazin-1(1H)-ones 3 by the reaction of 2-formylbenzoic acids 1 or 3-hydroxyisobenzofuran-1(3H)-ones 2 with hydrazine to generate phthalazin-1(2H)-ones 3. Subsequent regioselective bromination of phthalazin-1(2H)-ones 3 with benzyltrimethylammonium tribromide (BTMA-Br3) followed by mixed copper-copper oxide-catalyzed amination of 4-bromophthalazin-1(2H)-ones 4 with primary amines generates aminophthalazin-1(2H)-ones in good overall yields.

Copper-catalyzed alkylarylation of activated alkenes using isocyanides as the alkyl source: an efficient radical access to 3,3-dialkylated oxindoles

A novel copper-catalyzed oxidative cyclization of N-arylacrylamides for the synthesis of 3,3-dialkylated oxindoles is described using isocyanides as alkyl radical precursors.

Isocyanide-based multicomponent reactions in the synthesis of heterocycles

In this review, we update our previous presentation, underscoring the recent applications of isocyanides as privileged synthons in the synthesis of various heterocyclic compounds, especially focused on those synthesizedviamulticomponent reactions.

Synthesis of 3-Iminoindol-2-amines and Cyclic Enaminones via Palladium-Catalyzed Isocyanide Insertion-Cyclization

A palladium-catalyzed isocyanide insertion-cyclization using low-cost and readily accessible 2-haloanilines, 2-iodophenylethanones, and isocyanides for efficient synthesis of 3-iminoindol-2-amine and cyclic enaminone derivatives has been developed. The method features low-cost and readily accessible starting materials, reliable scalability, and bond-forming efficiency as well as simple one-pot operation, which makes this strategy highly attractive. A reasonable mechanism for forming 3-iminoindol-2-amine involved double isocyanide insertion/cyclization process is proposed.

Three-component reaction toward polyannulated quinazolinones, benzoxazinones, and benzothiazinones

An efficient conversion of readily accessible cyclic imines with acid chlorides, that are able to take part in nucleophilic aromatic substitution (SNAr) reactions is realized in a new three-component, one-pot reaction, giving at least tricyclic annulated quinazolinones, benzoxazinones, and benzothiazinones as a result of the employed nitrogen, oxygen, or sulfur nucleophiles, respectively. Especially in the case of quinazolinones, this convenient strategy enables the access to heterocycles of heightened diversity, which offer the development of efficient derivatizations of the elaborated heterocyclic scaffolds. In a subsequent Heck or Ullmann cyclization, further annulations to the mentioned quinazolinones can be carried out.

Synthesis of 1,2-dihydro-1-oxophthalazin-4-yl trifluoromethanesulfonate and its application in the synthesis of 4-(aryl/heteroaryl/alkynyl)phthalazin-1(2H)-one

Biologically significant 4-aryl/heteroaryl/alkynyl phthalazinones have been reported via the Suzuki and Sonogashira coupling reactions.

Palladium-catalyzed direct coupling of 2-vinylanilines and isocyanides: an efficient synthesis of 2-aminoquinolines

A variety of 2-aminoquinolines were prepared in good to excellent yields.

Catalytic Isonitrile Insertions and Condensations Initiated by RNC-X Complexation

Isonitriles are delicately poised chemical entities capable of being coaxed to react as nucleophiles or electrophiles. Directing this tunable reactivity with metal and non-metal catalysts provides rapid access to a large array of complex nitrogenous structures ideally functionalized for medicinal applications. Isonitrile insertion into transition metal complexes has featured in numerous synthetic and mechanistic studies, leading to rapid deployment of isonitriles in numerous catalytic processes, including multicomponent reactions (MCR). Covering the literature from 1990-2014, the present review collates reaction types to highlight reactivity trends and allow catalyst comparison.

Palladium-catalyzed synthesis of 2-aminobenzoxazinones by aerobic oxidative coupling of anthranilic acids and isocyanides

Isocyanides have emerged as valuable C1 building blocks in palladium catalysis. Their potential has, however, mainly been exploited for the synthesis of amidines and amidine-containing heterocycles. To illustrate the broader applicability of isocyanides, we have recently developed a novel oxidative coupling of diamines and isocyanides furnishing valuable guanidine-containing heterocycles. We here report the extension of this protocol to the coupling of anthranilic acids and isocyanides leading to medicinally relevant 2-aminobenzoxazinones. This is a particularly challenging substrate class for this reaction due to the possibility of undesired decarboxylative pathways and the susceptibility of the products to nucleophilic attack. Therefore, this work underlines the generality and broad potential of the oxidative coupling of bisnucleophiles and isocyanides, facilitating the further implementation of this chemistry in library design.