N-substituted -amino

In the case of the 2-dimethylamino- (or 2-amino-)methylene derivatives, the products were at first thought to be pyrimido[4,5-c]isoquinolines (267), but later work with 6-(N-substituted amino)uracils assigned the structures of the products (268) as belonging to the isomeric pyrimido[4,5-f>]quinoline system (74CB2537), in agreement with the regioselection rules above. 

When an a-amino acid is treated with an anhydride in the presence of pyridine, the carboxyl group is replaced by an acyl group and the NH2 becomes acylated. This is called the Dakin-West reaction The mechanism involves formation of an oxazolone. The reaction sometimes takes place on carboxylic acids even when an amino group is not present. A number of N-substituted amino acids, RCH-(NHR )COOH, give the corresponding N-alkylated products. 

Table 3.50 Structure and heat fastness of N-substituted amino-dihydroxyanthraquinone disperse dyes on polyester [190] ...

RE Bowman, HH Stroud. N-Substituted amino acids. I. A new method of preparation of dimethylamino acids. J Chem Soc 1342, 1950. 

The reaction between the sodium salt of diethyl 2-[2-(N-substituted amino)-4-thiazolyl]malonate (298) and diethyl chloromethylenemalonate in THF at ambient temperature for 1-10 hr occurred on the central carbon atom of the malonate (298), not on the amino group, to give tetraesters (299) in 10-70% yields (86EUP168025). 

Sato, R. Senzaki, T. Goto, T. Saito, M. Novel synthesis of 3-(N-substituted amino)-1-isoindolenones from 2-cyanobenzaldehyde with amines. Chem. Lett. 1984, 9, 1599-1602. 

N- Amino- and N-substituted amino-pyrroles readily undergo Diels-Alder additions and add to activated alkynes at room temperature. The resulting azanorbornadienes extrude N-aminonitrenes and this forms the basis of an unusual synthesis of benzene derivatives (81S753,81TL3347). It has been found that ethyl/3-phenylsulfonylpropiolate (135) is a superior dienophile to DMAD (Scheme 50). 

The synthesis of amino acids in which a nonfunctionalized alkyl group is covalently connected to the a-nitrogen has been discussed vide supra). In this section the synthesis of N-substituted amino acids in which the alkyl chain bears a protected functional group is discussed. The resulting amino acids have the general formula /Va-(m-functionalized alkyl) amino acids 28 (Scheme 17). These amino acids were developed for the solid-phase synthesis of backbone cyclic peptides 70 (see also Vol. E 22b, Section 6.8.3.2.4) [in this case they were called building units (BU)], for the synthesis of PNA 71 and for the synthesis of peptoids. 72 (In this case they were called monomers.)... 

As a substituent, the —NH2 group is called amino. N-Substituted amino groups are named accordingly ... 

The N-substituted amino acid (5 mmol) was added to an ice-cold stirred soln of Na2CO3T0H2O (16.0 mmol, 3.2-fold excess) in HjO (50 mL) and dioxane (30-50 mL) added to complete soln. A soln of Fmoc-Cl (10.2 mmol, 2.1-fold excess) in dioxane (10 mL) was then added over 1 h. An aliquot (5mL) of the mixture was withdrawn and was washed with Et20 (2 x 10 mL). The basic aqueous layer was acidified with 5M HC1 to pH 4, and washed with CHC13 (2 x 10 mL). The combined CHC13 layers were dried (Na2S04) and concentrated under reduced pressure to give the crude mono-Fmoc derivative. The remainder of the mixture was left to stir for a further 1-2 h after Fmoc-Cl addition, the originally clear... 

A series of 3-amino (or 3-N-substituted amino)-l,2,4-oxadiazoles 108 can be obtained in moderate to high yields by the photoinduced rearrangement of 3-acylamino-l,2,5-oxadiazoles (furazans) 106 irradiated in the presence of an excess of ammonia or aliphatic amines [64—66]. The reaction follows a fragmentation-cycloaddition route, with the initial formation of a nitrile and a nitrile-oxide the latter is attacked by a nitrogen nucleophilic reagent (ZH in Scheme 12.29), and the open-chain interme-... 

Reactions of A/-amino compounds with electrophiles. Af-Aminopyridinium cations can be acylated or sulfonylated (with acid halides) and nitrated (H2SO4-HNO3) to give the corresponding N-(substituted amino)pyridines, often isolated as the imides (1014 R = COR, S02R, or N02). 

S-Deazaflavins. A new synthesis of 5-deazaflavins (2), in which N5 of a flavin is replaced by CH, involves oxidative cyclization of 5-benzylidene-6-(N-substituted amino)uracils (1) with DAD at 150°. 

In synthesis of peptides containing adjacent sterically hindered or N-substituted amino acids, complete chain propagation may not be obtainable. More accessible sites on the resin may continue to grow well, whereas more hindered sites may fail, but couple in a later step with a less hindered amino acid, e.g. glycine. In these cases, dehberate termination by acetylation can prevent contanoination of the product by omission sequences which may be more difficult to remove during purification than a shorter acetylated peptide. Both acetylimidazole and acetic anhydride have been used successfully for such acetylation acetylimidazole is the more reactive of these two reagents. 

Analytical chromatographic separation of enantio-merie acids and N-substituted amino acids has been effeeted using immobilized a-chymotrypsin supported on aetivated siliea. Similarly, cellulase immobilized on silica gel ean bring about chromatographic... 

Ishikawa, R, Saegusa, J., Inamura, K., Sakuma, K., Ashida, S.-I. Cyclic guanidines. 17. Novel (N-substituted amino)imidazo[2,l-h] quinazolin-2-ones water-soluble platelet aggregation inhibitors. J. Med. Chem. 1985, 28, 1387-1393. 

Polymer-bound isonitrile (423), obtained from TentaGel-NH2 through treatment of the resin with formic acid and acetic anhydride, followed by dehydration of the resulting formamide with tosyl chloride and pyridine, has been employed in the preparation of N-substituted amino add ester [349]. Thus, Ugi MCR, performed in the presence of an alcohol instead of the carboxylic component, gave rise to an imino-ether spedes (426). Several Lewis acids were tested in searching for optimal reaction conditions. Boron trifluoride etherate displayed the better yields in term of desired product of the Ugi-type reaction. Amino acid methyl esters (427) were thus obtained when using methanol as the alcohol component, after deavage from the resin of the intermediate imino-ethers by an acetone/water mixture (Scheme 87). 

Another report describes syntheses of 6 -N-substituted amino acid derivatives of neamine with alanine, phenylalanine, and lysine. These neamine analogs were... 

Low-pressure hydrogenation of a-aminonitriles occurs without hydrogenolysis over platinum oxide in acetic anhydride (to the a,j8-diacetamido compound) or in alcohol-HCl (to the a,jS-diamine) . This procedure is not applicable to N-substituted amino-nitriles that are efficiently reduced using rhodium-on-alumina in alcoholic ammonia [equation (h)] the catalytic system also reduces )8-, y-, 5-aminonitriles to diamines. 

Acylation of /3,/3-dichloro-a-aminoacrylonitrile (126, an enamine, obtained by the base-catalyzed addition of hydrogen cyanide to dichloro-acetonitrile) followed by treatment with amines (primary or secondary) or hydrazines provides a new method of synthesis of 4-cyano-5-(N-substituted amino)-oxazoles (127) in almost quantitative yields.185... 

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