Isatins As Privileged Molecules in Design and Synthesis of Spiro-Fused Cyclic Frameworks

Heterocycles constitute the largest and the most diverse family of organic compounds Among them, aromatic heterocycles represent structural motifs found in a great number of biologically active natural and synthetic compounds, drugs, and agrochemicals Moreover, aromatic heterocycles are widely used for synthesis of dyes and polymeric materials of high value 1 There are numerous reports on employment of aromatic heterocycles as intermediates in organic synthesis 2

Although, a variety of highly efficient methodologies for synthesis of aromatic heterocycles and their derivatives have been reported in the past, the development of novel methodologies is in cuntinious demand Particlularly, development of new synthetic approaches toward heterocycles, aiming at achieving greater levels of molecular complexity and better functional group compatibilities in a convergent and atom economical fashions from readily accessible starting materials and under mild reaction conditions, is one of a major research endeavor in modern synthetic organic chemistry Transition metal-catalyzed transformations, which often help to meet the above criteria, are among the most attractive synthetic tools

Several excellent reviews dealing with transition metal-catalyzed synthesis of heterocyclic compounds have been published in literature during recent years Many of them highlighted the use of a particular transition metal, such as gold,3 silver,4 palladium,5 copper,6 cobalt,7 ruthenium,8 iron,9 mercury,10 rare-earth metals,11 and others Another array of reviews described the use of a specific kind of transformation, for instance, intramolecular nucleophilic attack of heteroatom at multiple C–C bonds,12 Sonogashira reaction,13 cycloaddition reactions,14 cycloisomerization reactions,15 C–H bond activation processes,16 metathesis reactions,17 etc Reviews devoted to an application of a particular type of starting materials have also been published Thus, for example, applications of isocyanides,18 diazocompounds,19 or azides20 have been discussed In addition, a significant attention was given to transition metal-catalyzed multicomponent syntheses of heterocycles21 Finally, syntheses of heterocycles featuring formation of intermediates, such as nitrenes,22 vinylidenes,23 carbenes, and carbenoids24 have also been reviewed

The main focus of the present review is a transition metal-catalyzed synthesis of aromatic monocyclic heterocycles The organization of the review is rather classical and is based on a heterocycle, categorized in the following order: (a) ring size of heterocycle, (b) number of heteroatoms, (c) type of heterocycle, and (d) a class of transformation involved A brief mechanistic discussion is given to provide information about a possible reaction pathway when necessary The review mostly discusses recent literature, starting from 200425 until the end of 2011, however, some earlier parent transformations are discussed when needed

Transition Metal-Mediated Synthesis of Monocyclic Aromatic Heterocycles

Multicomponent reactions are one of the most interesting concepts in modern synthetic chemistry and, as shown in this critical review, they provide an attractive entry into pyrrole derivatives, which are very important heterocycles from many points of view including medicinal and pharmaceutical chemistry and materials science (97 references).

Multicomponent reactions for the synthesis of pyrroles

The present invention relates to an electronic device comprising anode, cathode and at least one organic layer which comprises a compound of the formula (I) to (IV). The invention furthermore encompasses the use of compounds of the formula (I) to (IV) in an electronic device and to a compound of the formula (Ic) to (IVc).

Materials for electronic devices

Pyrrole is widely known as a biologically active scaffold which possesses a diverse nature of activities. The combination of different pharmacophores in a pyrrole ring system has led to the formation of more active compounds. Pyrrole containing analogs are considered as a potential source of biologically active compounds that contains a significant set of advantageous properties and can be found in many natural products. The marketed drugs containing a pyrrole ring system are known to have many biological properties such as antipsychotic, β-adrenergic antagonist, anxiolytic, anticancer (leukemia, lymphoma and myelofibrosis etc.), antibacterial, antifungal, antiprotozoal, antimalarial and many more. Due to the diversity of these analogs in the therapeutic response profile, many researchers have been working to explore this skeleton to its maximum potential against several diseases or disorders. In this review, attempts have been made to disclose various tactical approaches to synthesize pyrrole and pyrrole containing analogs. The structure–activity relationship studies have been discussed along with their therapeutic applications which have been reported during last decade. Some molecules as the main components of the market and clinical trials have also been discussed.

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Pyrrole: a resourceful small molecule in key medicinal hetero-aromatics

An efficient, convenient, one-pot synthesis of 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazolin-5(1H)-one and 2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-1,5-dione was accomplished in good yields via the novel reductive cyclization of 2-nitrobenzamides with haloketones or keto acids mediated by SnCl2·2H2O system. A variety of substrates can participate in the process with good yields, making this methodology suitable for library synthesis in drug discovery efforts.

Efficient and convenient synthesis of pyrrolo[1,2-a]quinazoline derivatives with the aid of tin(II) chloride.

A mild, efficient, one-pot protocol for the synthesis of indazole-3(2H)-ones via cyclization of nitro-aryl substrates through low-valent titanium reagent has been described. The method used Triethylamine (TEA) to control pH. Particularly, 2-aminobenzonitriles were synthesized by one step easily. The mechanistic course of the reaction suggests the involvement of an anion leading to an intramolecular cyclization via N−N bond formation.

Efficient and convenient synthesis of indazol-3(2H)-ones and 2-aminobenzonitriles.

Efficient Synthesis of 2-Arylbenzothiazole Derivatives with the Aid of a Low-Valent Titanium Reagent

One‐pot synthesis of quinazoline‐2,4(1H,3H)‐diones and 2‐thioxoquinazolinones with the aid of low‐valent titanium reagent

A short and efficient synthesis of substituted pyrroles was accomplished in good yields via the novel coupling cyclization reaction of 1,3-diketones with imines promoted by low-valent titanium reagent. High regioselectivity was achieved and the structures of two of the products were confirmed by X-ray diffraction studies.

Guolan Dou

Papers

Efficient and convenient synthesis of pyrrolo[1,2-a]quinazoline derivatives with the aid of tin(II) chloride.

Efficient and convenient synthesis of indazol-3(2H)-ones and 2-aminobenzonitriles.

Efficient Synthesis of 2-Arylbenzothiazole Derivatives with the Aid of a Low-Valent Titanium Reagent

One‐pot synthesis of quinazoline‐2,4(1H,3H)‐diones and 2‐thioxoquinazolinones with the aid of low‐valent titanium reagent

Highly Regioselective Synthesis of Substituted Pyrroles Utilizing Low-Valent Titanium Reagent