Amines and Heterocycles

Amines are classified as primary (RNH2), secondary (R2NH), tertiary (R3N) or quaternary ammonium salts (R4NH. 

Heterocyclic amines (nitrogen is part of a ring) have specific parent names. 

The three amine bonds and the lone pair occupy the comers of a tetrahedron. 

An amine with three different substituents is chiral. 

Amines with fewer than 5 carbons are water-soluble and form hydrogen bonds. 

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Amines ate organic derivatives of ammonia in the same way thal alcohois and ethers arc organic derivatives of water, hike ammonia, amines contain a nitrogen atom with a lone pair of electrons, making amines both basic and nucleophilic. VVeMl soon see, in fact, tl iat most of the chemistry of amines depends on the presence of this lone pair t)f electrons. 

Amines occur widely in all living organisms. Trimethylamine, for instance, occurs in animal tissues and is partially responsible for the distinctive odor of fish, nicotine is found in tobacco, and cocaine is a stimulant found in the South American coca bush. In addition, amino acids arc the building blocks from which all proteins are made, and cyclic amine bases arc constituents of nucleic acids. 

By the end of this chapter, wc will have seen all the common functional groups. Of those groups, amines and carbonyl compounds are the most abundant and have the richest chemistry. In addition to the proteins and nucleic acids already mentioned, the majoritv of pharmaceutical agents contain amine functional groups, and many of the common coenzymes necessary for biological catalysis are amines. 

Glutamine synthase catalyzes the reductive amina-tion ofa-ketoglutarateto give glutamate, a step in amino acid metabolism. 

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Styphnates. Aromatic hydrocarbons (and also some amines and heterocyclic bases) form 1 1-addition products with styphnic acid (2 4 6-trinitroresorcinol),... 

In addition to bromides and iodides, the reaction has been successfully extended to chlorides,163 triflates,164 and nonafluorobutanesulfonates (nonaflates).165 These reaction conditions permit substitution in both electron-poor and electron-rich aryl systems by a variety of nitrogen nucleophiles, including alkyl or aryl amines and heterocycles. These reactions proceed via a catalytic cycle involving Pd(0) and Pd(II) intermediates. 

Compounds with an acidity constant, pK, in the range of 4 to 10, i.e. weak organic acids or bases, are present in two species forms at ambient pH. This pA a.i. range includes aromatic alcohols and thiols, carboxylic acids, aromatic amines and heterocyclic amines [15]. Conversely, alkyl-H and saturated alcohols do not undergo protonation/deprotonation in water (pA iw 14). 

Zeitler K (2006) Stereoselective synthesis of (E)-afi—unsaturated esters via carbene-catalyzed redox esterification. Qrg Lett 8 637-640 Zeitler K, Mager I (2007) An efficient and versatile approach for the immobilization of carbene precursors via copper-catalyzed [3+2]-cycloaddition and their catalytic apphcation. Adv Synth Cat 349 1851-1857 Zhao GL, Cordova A (2007) A one-pot combination of amine and heterocyclic carbene catalysis direct asymmetric synthesis of fi-hydroxy and fS-malonale esters from a,fS-unsaturated aldehydes. Tetrahedron Lett 48 5976-5980 Zhou ZZ, Ji FQ, Cao M, Yang GF (2006) An efficient intramolecular Stetter reaction in room temperature ionic liquids promoted by microwave irradiation. Adv Synth Cat 348 1826-1830... 

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