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

Chemistry of Acyl Radicals

Synthesis and biological activity of pyrrole, pyrroline and pyrrolidine derivatives with two aryl groups on adjacent positions

Recent developments in the chemistry of enaminones

Tautomeric equilibria in relation to pi-electron delocalization.

Recent development in preparation reactivity and biological activity of enaminoketones and enaminothiones and their utilization to prepare heterocyclic compounds

A high-transmission Extrel pentaquadrupole mass spectrometer was interfaced to an IBM-compatible microcomputer, and a variety of object-oriented programs in the Microsoft Windows operating system were developed to operate and to increase the versatility of the instrument. A selective prescan procedure and the complete control of all three mass-scanning quadrupoles made possible very fast acquisition of several types of three- and four-dimensional MS2 and MS3 spectra, while the high transmission of the quadrupoles conferred excellent signal-to-noise levels to both MS2 and MS3 spectra. By performing an unrestricted third-order (MS3) experiment through scanning of the three mass-analyzer quadrupoles, an entire MS3 data domain was acquired, and the results were collected in the first 4D MS3 mass spectrum. Data projection and data extraction procedures were applied to the 4D spectrum, each of which yielded spectra that provide very specific analytical information. The applicabilities of this and several other ...

Fast Multidimensional (3D and 4D) MS2 and MS3 Scans in a High-Transmission Pentaquadrupole Mass Spectrometer

After thirty two years in Brazil and retired from Universidade Estadual de Campinas the author wishes to present this account, a summary of a large part of the research in synthetic methodology developed by the research groups of Albert J. Kascheres and the author at Universidade Estadual de Campinas Chemistry Institute. Contributions have been made to the area of enaminones, diazocarbonyls, cyclopropenones and azirines.

https://www.scielo.br/pdf/jbchs/v14n6/18637.pdf

The chemistry of enaminones, diazocarbonyls and small rings: our contribution

Catalyzed reaction of diazodiphenylethanone and related diazo ketones with enaminones as a source of pyrroles

A new and efficient method of 1,2,3-triazole synthesis is described in which these heterocyclics are formed through a novel nitrogen transfer from diazocarbonyl compounds to enaminones. Thus, the reaction of 3-diazo-1,3-dihydro-2H-indol-2-one derivatives 1 (X = NR3) and 3-diazobenzo[6]thiophen-2(3H)-one 5 (X = S) with enaminones 2 and 7 leads to the formation of mainly 1,2,3-triazoles 4 and pyrazoloquinazolinones 3. Both the phenyl substituants (Y and Z in 1) and the nature of the X group affects the reaction rate and product distribution. Rate increases with an increase in the electron-withdrawing ability of the substituants Y and Z. The dinitro derivative 1g is shown to be the most efficient in promoting 1,2,3-triazole 4 formation while pyrazoloquinazolinones 3 are often competitively formed when other derivatives of 1 are employed. © 1993 American Chemical Society.

Concetta Kascheres

Papers

Recent development in preparation reactivity and biological activity of enaminoketones and enaminothiones and their utilization to prepare heterocyclic compounds

Fast Multidimensional (3D and 4D) MS2 and MS3 Scans in a High-Transmission Pentaquadrupole Mass Spectrometer

The chemistry of enaminones, diazocarbonyls and small rings: our contribution

Catalyzed reaction of diazodiphenylethanone and related diazo ketones with enaminones as a source of pyrroles

Reactions of 3-diazo-1,3-dihydro-2H-indol-2-one derivatives with enaminones. A novel synthesis of 1,2,3-triazoles