Amine components

The major development in the Knorr pyrrole synthesis has been access to the amine component. For example, use of preformed diethyl aminomalonate with 1,3-diketones affords much higher yields of pyrroles 14. Reaction of 6-dicarbonyl compounds with hydroxylamine 0-sulfonic acid gives pyrroles 15 in one step. Weinreb a-aminoamides have found use in the Knorr pyrrole synthesis of a wide variety of pyrroles 16. °... 

A seven-membered fused ring system 66 (85-95%) has been built by variation of the amine component. Tliis example deals with the reaction of 33 with 3-(2-aminophenyl)amino-5,5-dimethylcyclohex-2-enone (65)... 

Instead of formaldehyde, other aldehydes or ketones may be used—aliphatic as well as aromatic recently methylene dihalides have been employed with success. The amine component is often employed as hydrochloride in addition to... 

Introducing yet more structural complexity into the amine component leads to the antiarrhythmic agent disobutamide (24). Disobutamide is structurally related to disopyramide but... 

In addition, we found that all of the functional monomers having amino group would act as an amine component and with LPO form a redox system to initiate the polymerization of functional monomer itself with the rate of polymerization as ... 

When the functional monomer is in low concentration, it can be used as an amine component of a redox initiation... 

Because FIC1 is formed during the reaction, two equivalents of the amine must be used. One equivalent reacts with the acid chloride, and one equivalent reacts with the HC1 by-product to form an ammonium chloride salt. If, however, the amine component is valuable, amide synthesis is often carried out using 1 equivalent of the amine plus 1 equivalent of an inexpensive base such as NaOH. For example, the sedative trimetozine is prepared commercially by... 

Figure 24.2 Separation and purification of an amine component from a mixture.

Strategy Look at the target molecule, and identify the groups attached to nitrogen. One of the groups must be derived from the aldehyde or ketone component, and the other must be derived from the amine component. In the case of iV-methyl-2-phenylcthyl-arnine, there are two combinations that can lead to the product phenvjacetaldehyde plus methylamine or formaldehyde plus 2-pbenylethylamine. In general, it s usually better to choose the combination with the simpler amine component—methyl-amine in this case—and to use an excess of that amine as reactant. 

Tannin-based multiblends cannot incorporate amines directly into their formulations (unlike sulfite-based multiblends). The neutralizing amine component must be added separately when using tannin multiblends. 

For a review where the amine component is an amino acid, see Agababyan, A.G. ... 

Some advances have been made in the Paal-Knorr synthesis of pyrroles by the condensation of primary amines with 1,4-dicarbonyl species. For instance, a new synthetic route to monosubstituted succinaldehydes allows for the facile preparation of 3-substituted pyrroles <96TL4099>. Additionally, a general method for the synthesis of 1-aminopyiroles has been devised by the condensation of commercially available 2,2,2-trichloroethyl- or 2-(tri-methylsilyl)ethylhydrazine with 1,4-dicarbonyl compounds <96JOCl 180>. A related route to such compounds involves the reaction of a-halohydrazones with p-dicarbonyl compounds <96H(43)1447>. Finally, hexamethyldisilazane (HMDS) can be utilized as the amine component in the Paal-Knorr synthesis in the presence of alumina, and this modification has been employed in the synthesis of tm azaprostacyclin analog <96S1336>. 

Dispersantfor Sulfur. The deposition of elemental sulfur in conduits through which a sulfur-containing gas is flowing can be reduced by providing a sulfur dispersant. The dispersant is an adduct of a primary alcohol and epichloro-hydrin, mixed with an aliphatic amine component [554]. 

An equimolar mixture of N-butyl- and N-octyl-(l-deoxyglucityl)amine was used as the amine component. 

A valuable application of sodium cyanoborohydride is in the synthesis of amines by reductive amination. What combination of carbonyl and amine components would give the following amines by this method ... 

An excess of CDI must be avoided because this would react with the amine component to give a urea derivative. 53 Further examples are compiled in Table 5—1. 

The first practical, large-scale synthesis of 2-amino-5-fluorothiazole 84 employs the reaction of dilithiated 2-butoxycarbonylaminothiazole 83 with A-fluorobenzenesulfonimide (NFSi) <06OPRD346>. This reaction generates a 70 15 mixture of the desired fluorinated thiazole 84 and the sulphone 85, and after three consecutive recrystallizations thiazole 84 is isolated in 35-40% yield. This procedure has been utilized to prepare multikilogram quantities of 84, which is a heterocyclic amine component of a series of glucokinase inhibitors. 

A facile synthesis of 5-substituted 3-aminopyrrole-2-carboxylates has been developed wherein condensation of diethyl aminomalonate with a-cyano ketones 46 was facilitated by prior formation of the p-toluenesulfonyl enol ether 47 <00JOC2603>. Addition of the amine component is followed by cyclization and decarboxylation to afford the pyrroles 48. 

A product of the U-4CR is only formed in a good yield and purity if the optimal reaction conditions are used. The U-4CR proceeds faster and in a higher yield, when the amine component and the carbonyl compound are precondensed, and the acid component and the isocyanide are added laterVery often methanol or trifluoroethanol are suitable solvents, but sometimes a variety of other solvents can be used as well. Furthermore, the sequence of the educts and their concentrations must be optimal and a suitable temperature of the reaction must be used. In many cases, the U-4CR can be improved by a catalyst. 

After the U-4CR had been introduced, it was soon recognized that this reaction can form diastereomeric products from chiral amine components, for example, chiral a-ferrocenyl-alkylamines. 

Zychlinski prepared 1 -amino-5-deoxy-5-acetamido-2,3,4-tri-6)-acetyl- 3-D-glucopyranose 60 by a synthesis of 11 steps. This amine component undergoes the U-4CRs very well and the products are cleavable by water, but unfortunately they are not very stable. 

The auxiliary carbohydrate parts of the products could be removed only moderately. The most efficient cleavages were achieved when the U-4CR products of the amine component 62 were treated with 1 M HCl in methanol at 40°C for 19 h. In that case, yields up to 30% could be achieved for Y = NH-CO-4-MeOPh in compound 62, the cleavage rate could be increased up to a yield of 46%. 

The presence of two chiral units in ligand 18 results in a matched (S, R, R) and a mismatched (S, S, S) combination. The absolute stereochemistry of the product is controlled by the BINOL moiety and the amine component has a distinct effect in... 

The photolysis of donor-acceptor systems provides unique synthetic opportunities. Direct irradiation of the donor-acceptor systems, such as systems containing arene and amine components, leads to intramolecular electron transfer, that is, to amine cation-radical and arene anion-radical moieties. After generation, these moieties undergo cyclization reactions providing efficient synthetic routes to fV-heterocycles with a variety of ring sizes. Thus, direct irradiation of secondary amino-ethyl and aminopropyl stilbenes leads to benzazepines in improved yields (Hintz et al. 1996). As known, benzazepines are used in medicine as antidepressants. Scheme 7.44 illustrates ion-radical cyclization with the formation of benzazepine derivative (65% yield). 

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