Heterocyclic tertiary amines

Other heterocyclic tertiary amines show a different behavior. Tertiary amines have been used as catalysts in dichlorocyclopropanation of olefins they probably give an ammonium ylide as the first step in the catalytic cycle.262 These ylides are usually unstable and undergo a variety of transformations such as the Stevens rearrangement and the Hoffmann elimination. 

In general, tertiary amines do not readily form coordination compounds, the order of stability of metal-amine complexes being tertiary < secondary < primary < ammonia. However, the heterocyclic, tertiary amine pyridine, a compound of relatively high dipole moment, coordinates readily, and many pyridine complexes have been prepared. 

The reactions between Re3X9 (X = Cl or Br) and the more basic heterocyclic tertiary amines (L) that result in the reduction of the cluster and the formation of [Re Lj], (Section 43.4.3) are known to proceed via the intermediacy of Re3X9L3, since purple Re3Cl9py3 can first be isolated by careful control of the reaction conditions.79 The less basic amines such as pyrazine, 2,6-dimethylpyrazine and 3-chloropyridine give unreduced Re3X9L3. Similar 1 3 adducts have also been prepared by the reactions of Re3Cl9 with acetonitrile and benzonitrile.5... 

Heterocyclic tertiary amines as catalysts for the reaction of activated vinyl carbanions with aldehydes 88T4653. 

Ans. Both nitrogen atoms in the 6-membered ring of caffeine are part of tertiary amide groups. Both nitrogens in the 5-membered ring of caffeine are part of heterocyclic tertiary amine groups. Amphetamine contains a primary amine group. 

Tertiary amines may be obtained from alkaline alkylation of secondary amines (46), but mixtures are obtained (see Section III.l.B) hence heterocyclization and ammonolysis of 2-halothiazoles are to be preferred. 

Butler recently reviewed the diazotization of heterocyclic amines (317). Reactions with nitrous acid yield in most cases N-exocyclic compounds. Since tertiary amines are usually regarded as inen to nitrosation, this... 

N -Heterocyclic Sulfanilamides. The parent sulfanilamide is manufactured by the reaction of A/-acetylsulfanilyl chloride with excess concentrated aqueous ammonia, and hydrolysis of the product. Most heterocycHc amines are less reactive, and the condensation with the sulfonyl chloride is usually done in anhydrous media in the presence of an acid-binding agent. Use of anhydrous conditions avoids hydrolytic destmction of the sulfonyl chloride. The solvent and acid-binding functions are commonly filled by pyridine, or by mixtures of pyridine and acetone. Tertiary amines, such as triethylamine, may be substituted for pyridine. The majority of A/ -heterocycHc sulfanilamides are made by simple condensation with A/-acetylsulfanilyl chloride and hydrolysis. 

The nitrogen of aHphatic and aromatic amines is alkylated rapidly by alkyl sulfates yielding the usual mixtures. Most tertiary amines and nitrogen heterocycles are converted to quaternary ammonium salts, unless the nitrogen is of very low basicity, eg, ia tn phenylamine. The position of dimethyl sulfate-produced methylation of several heterocycles with more than one heteroatom has been examined (22). Acyl cyanamides can be methylated (23). Metal cyanates are converted to methyl isocyanate or ethyl isocyanate ia high yields by heating the mixtures (24,25). 

Heterocyclic Alcohols. Thek reactions with chloroformates lead to carbonates. Thus furan- and tetrahydrofuran-derived alcohols give the corresponding carbonates in 75% yield (15). Inorganic bases and tertiary amines as acid acceptors increase the rate and yield in this reaction. 

Nearly every substitution of the aromatic ring has been tolerated for the cyclization step using thermal conditions, while acid-promoted conditions limited the functionality utilized. Substituents included halogens, esters, nitriles, nitro, thio-ethers, tertiary amines, alkyl, ethers, acetates, ketals, and amides. Primary and secondary amines are not well tolerated and poor yield resulted in the cyclization containing a free phenol. The Gould-Jacobs reaction has been applied to heterocycles attached and fused to the aniline. 

The tertiary amine can be aliphatic, cycloalkyl, or heterocyclic (including pyridine). 

In summary, the preparation of polyimidazolinones from polyamides containing a-aminoacid units (3, X = NH) can now be considered to be a general reaction provided that Rz and/or R3 are not hydrogen. When the polyamide has additional secondary or tertiary amine functionality in the backbone, cyclodehydration appears to be exceptionally facile. In the absence of amine functionality however, a catalyst is necessary to promote cyclization. Further studies of this new heterocyclic polymer system are ongoing in our laboratories. 

Molecules whose sole heterocyclic moiety consists of a pyrrolidine ring are dealt with elsewhere in this book. There is a wealth of evidence to indicate that N-alkylpyrrolidine is usually a surrogate for a tertiary amine. 

Refaat et al. [24] used a spectrophotometric method for the determination of primaquine, and 16 other tertiary amine drugs, in bulk or in pharmaceuticals. The method involved the condensation of malonic acid with acetic anhydride in the presence of a tertiary amine in an aliphatic or a heterocyclic system. The condensation product is highly fluorescent and allows the spectrofluorimetric determination of the drug in the ng/mL ranges (Xcx = 415 nm and >.em = 455 nm). 

Quatemization of Tertiary Amines and Nitrogen-Containing Heterocycles with N,N-Bis(siloxy)Enamines Ammonium salts [HON=CR,CHR"NEt3]+ X- were found for the first time as by-products in studies of double silylation of AN (465, 466). To optimize the reaction, efforts were made to reduce the... 

Photolysis or thermolysis of heteroatom-substituted chromium carbene complexes can lead to the formation of ketene-like intermediates (cf. Sections 2.2.3 and 2.2.5). The reaction of these intermediates with tertiary amines can yield ammonium ylides, which can undergo Stevens rearrangement [294,365,366] (see also Entry 6, Table 2.14 and Experimental Procedure 2.2.1). This reaction sequence has been used to prepare pyrrolidones and other nitrogen-containing heterocycles. Examples of such reactions are given in Figure 2.31 and Table 2.21. 

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