Reactions with Compounds

Two interesting cases of quaternary salt formation are illustrated by compounds 88 and 90 (Z = CH) which contain fused quinoline and triazole rings. In these compounds both of the nitrogen atoms unique to the triazole ring possess lone pairs of electrons which are available for reaction. With compound 88 reaction occurs to give 89, but in... 

Ionic interactions have been used to prepare lanthanide-core dendrimers. This has been achieved using a convergent synthesis, in which polyether den-drons with a carboxylic acid group at the focal point were assembled around a lanathanide cation. This involved a metathetical reaction with compounds such as Er(OAc)3, Tb(OAc)3 or Eu(OAc)3 to introduce the appropriate lanthanide ion. 

When a heteroatom, such as N, O, or a halogen, is present in a molecule containing an aromatic ring or a double bond, lithiation is usually quite regio-selective. The lithium usually bonds with the sp carbon closest to the hetero atom, probably because the attacking species coordinates with the hetero atom. Such reactions with compounds such as anisole are often called directed metala-tions. In the case of aromatic rings, this means attack at the ortho position.Two examples are... 

Platinum(O) phosphine complexes undergo a variety of oxidative addition reactions with compounds containing Group 14 elements. These reactions are of widespread interest because similar processes are probably involved in the catalysis by platinum complexes of reactions such as the hydrosilation of alkenes and the disilylation of dienes and alkenes. 

A Reactions with Compounds Containing Acidic Hydrogen Atoms... 

Zinc dust is frequently covered with a thin layer of zinc oxide which deactivates its surface and causes induction periods in reactions with compounds. This disadvantage can be removed by a proper activation of zinc dust immediately prior to use. Such an activation can be achieved by a 3-4-minute contact with very dilute (0.5-2%) hydrochloric acid followed by washing with water, ethanol, acetone and ether [/55]. Similar activation is carried out in situ by a small amount of anhydrous zinc chloride [156 or zinc bromide [157 in alcohol, ether or tetrahydrofuran. Another way of activating zinc dust is by its conversion to a zinc-copper couple by stirring it (180g) with a solution of 1 g of copper sulfate pentahydrate in 35 ml of water [/55]. 

The chalcogenides are synthesized either by reaction of the chalcogen vapour with the actinide metal or the hydride (Faraday-method), or in reaction with compounds ... 

Aminothiophene, readily available from methyl 3-aminothiophene-2-carboxylate, undergoes a condensation reaction with compound 92, followed by heating at elevated temperatures in Dowtherm , to produce pyridone product (Equation 28). The pyridone can be converted into a thieno[3,2- ]pyridine derivative in a few straightforward steps <2004BML21>. 

Pyran-4-ones, chromones and flavones are converted into pyrimidines, usually under base catalysis, by reaction with compounds which contain the grouping N—C—N urea, thiourea, guanidine, aminoguanidine, acetamidine and dicyandiamide are examples of this type. Scheme 24 shows some typical examples (77BSF369, 81JHC619). 

The formation of acylnaphthalenes 225 occurs under mild conditions (catalysis by sodium rm-butoxide or with the use of the phase-transfer method and TEBA as catalyst), and it affords high yields (60-90%). In this connection, it is surprising to recall the opinion about the incapability of 2-benzopyrylium salts to take part in recyclization reactions with compounds possessing active methylene groups, with secondary amines, or with sulfur or phosphorus nucleophiles (71CB2984). 

Formation of the electrophilic halogen species leads to the potential for rapid reaction with compounds containing strongly activating groups, such as activated aryl compounds. Particularly, substances containing aromatic ring structures that have... 

The reaction of an amine with, principally, formaldehyde, followed by further reaction with compounds having active hydrogen atoms, give rise to the Mannich bases which are discussed in Sections 5.18.2, p. 801, and 6.12.7, p. 1050. 

These coordinatively unsaturated complexes can undergo coordination reactions with compounds having a free electron-pair donor group, particularly pyridine, amines, ammonia, and water. Coordination is associated with a marked hyp-sochromic color change. For example, the unsaturated nickel complex36 is green and its pyridine adduct 37 is violet [74],... 

Carbonylation occurs by the oxidation of some amino acid side chains into ketone or aldehyde derivatives by reactions with compounds of lipid oxidation or by glycoxidation with reducing sugars. These protein-carbonyl compounds are markers of protein oxidation, and recently, several carbonylated proteins and protein oxidation sites in milk (96), meat (97), and fishes (98) have been identified using a classical bottom-up proteomics approach based on 2-DE and MS/MS. Specific labeling of protein carbonyls using fluorescein-5-thiosemicarbazide has been developed and combined with 2-DE and... 

Discovered over a century ago, electrophilic mercuration is probably the oldest known C-H bond-activation reaction with a metal compound. The earliest examples of aromatic mercuration were reported by Volhard (mercuration of thiophene) [1], Pesci (mercuration of aromatic amines) [2], and Dimroth [3], who was the first to mercurate benzene and toluene, generalize the reaction, and assign the correct structures to the products originally observed by Pesci. Since the work of Dimroth electrophilic aromatic metalation reactions with compounds of other metals, for example Tl(III), Pb(IV), Sn(IV), Pt(IV), Au(III), Rh(III), and Pd(II), have been discovered [4], In this chapter, we will focus on intermolecular SEAr reactions involving main-group metal electrophiles and resulting in the formation of isolable metal aryls which find numerous important applications in synthesis [5], Well-known electrophilic cyclometalation reactions, for example cyclopalla-dation can be found in other chapters of this book and will not be reviewed here. 

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