Copper-catalyzed Ullmann condensations are key reactions for the formation of carbon-heteroatom and carbon-carbon bonds in organic synthesis. These reactions can lead to structural moieties that are prevalent in building blocks of active molecules in the life sciences and in many material precursors. An increasing number of publications have appeared concerning Ullmann-type intermolecular reactions for the coupling of aryl and vinyl halides with N, O, and C nucleophiles, and this Minireview highlights recent and major developments in this topic since 2004.

Catalytic C-C, C-N, and C-O Ullmann-type coupling reactions.

2.7. Hydroxylation Reactions of Allenes 3282 2.8. Hydroamination Reactions of Allenes 3284 2.9. Hydrothiolation of Allenes 3284 2.10. Hydroalxoxylation of Alkenes and 1,3-Dienes 3286 2.11. Hydroamination of Alkenes and 1,3-Dienes 3287 2.12. Hydrothiolation of Conjugated Olefins 3289 3. Activation of Carbonyl/Imine Groups and Alcohols 3289 3.1. Condensation Reactions 3289 3.2. Addition Reactions 3291 3.3. Aldol Reactions 3294 3.4. Hydroand Carbosilylation Reactions 3295 3.5. Nucleophilic Substitution Reactions of Alcohols 3297 4. Gold-Catalyzed C-H Bond Functionalization 3297 4.1. Csp3-H Bond Functionalization 3298 4.2. Csp2-H Bond Functionalization 3299 4.3. Csp-H Bond Functionalization 3304 5. Gold-Catalyzed Selective Reductions 3305 5.1. Catalytic Hydrogenation of Alkenes 3306 5.2. Selective Reductions of R, -Unsaturated Carbonyl Groups and 1,3-Dienes 3306

Alternative synthetic methods through new developments in catalysis by gold.

From 2000 to mid-2010: a fruitful decade for the synthesis of pyrazoles.

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

Metal nanoparticles have attracted much attention over the last decade owing to their unique properties as compared to their bulk metal equivalents, including a large surface-to-volume ratio and tunable shapes. To control the properties of nanoparticles with particular respect to shape, size and dispersity is imperative, as these will determine the activity in the desired application. Supported metal nanoparticles are widely employed in catalysis. Recent advances in controlling the shape and size of nanoparticles have opened the possibility to optimise the particle geometry for enhanced catalytic activity, providing the optimum size and surface properties for specific applications. This Review describes the state of the art with respect to the preparation and use of supported metal nanoparticles in catalysis. The main groups of such nanoparticles (noble and transition metal nanoparticles) are highlighted and future prospects are discussed.

Sustainable Preparation of Supported Metal Nanoparticles and Their Applications in Catalysis

Nanocrystalline ZnO is an effective heterogeneous catalyst for the [2+3]-cycloaddition of sodium azide with nitriles to afford 5-substituted 1H-tetrazoles in good yields

Nanocrystalline ZnO as an Efficient Heterogeneous Catalyst for the Synthesis of 5‐Substituted 1H‐Tetrazoles

Zn/Al hydrotalcite is an effective heterogeneous catalyst for the (2 + 3) cycloaddition of sodium azide with nitriles to afford 5-substituted 1 H -tetrazoles in good yields. The catalyst is recovered and reused for several cycles with consistent activity.

K. B. Shiva Kumar

Papers

Nanocrystalline ZnO as an Efficient Heterogeneous Catalyst for the Synthesis of 5‐Substituted 1H‐Tetrazoles

An efficient synthesis of 5-substituted 1H-tetrazoles using Zn/Al hydrotalcite catalyst

Zinc Hydroxyapatite–Catalyzed Efficient Synthesis of 5‐Substituted 1H‐Tetrazoles

Efficient one-pot synthesis of propargylamines using zinc dust

Copper fluorapatite catalyzed N-arylation of heterocycles with bromo and iodoarenes