N-methyl amino adds

The very strong cytotoxidly of these derivatives would come from the presence of N-methyl amino adds. It has been shown that some of them were synthesized through the ribosomal pathway (Subtelny, Hartman, and Szostak, 2008). Coibamide A, isolated from the Panamanian (Coiba National Park) filamentous cyanobaderium Leptolyr bya sp., is cytotoxic in the nanomolar range without any action on the cytoskeleton its mechanism of action remains tmdetermined (Medina et al., 2008). 

Although containing no N-methylated amino adds, hectochlorin is a potent stimulator of actin assembly it was isolated in Guam, Palau, Jamaica and Panama (Luesch et al., 2002a, 2002b Marquez et al., 2002). 

D, L-N-trifluoro acetyl -a-methyl amino add L-amino acid D-N-trifluoro acetyl-a-methy amino add... 

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). 

Laplante, C. Hall, D. G. Direct mono-N-methylation of solid-supported amino adds a useful application of the Matteson rearrangement of a-aminoalkylboronic esters. Org. Lett. 2001, 3, 1487-1490. 

Breukel AIM, Besselsen E, da Silva FHL, Ghijsen WEJM (1998) A presynaptic N methyl d aspartate autoreceptor in rat hippocampus modulating amino add release from a cytoplasmic pool. 

Furthermore, the incorporation of d-amino acids or other unusual (often hydroxylated) amino adds, the N-methylation of amide functionalities or the usage of cyclic peptides and depsipeptides limits these problems to a certain extent. 

Casimir, J.R., Guichard, G., and Briand, J.-P. (2002) Methyl-2-(sucdnimidyl-N-oxycarbonyljbenzoate (MBS). A new, efficient reagent for N-phthaloylation of amino add and peptide derivatives. Journal of Organic Chemistry, 67, 3764—3768. 

An important application of oxidation of a C-H bond adjacent to a nitrogen atom is the selective oxidation of amides. This reaction proceeds in the presence of ferf-BuOOH as the oxidant and Ru(II) salts. Thus in the example of Eq. (36), the a-tert-butylperoxy amide of the isoquinoline was obtained, which is an important synthetic intermediate for natural products [138]. This product can be conveniently reacted with a nucleophile in the presence of a Lewis add. Direct trapping of the iminium ion complex by a nudeophile was achieved in the presence of trimethylsilyl cyanide, giving a-cyanated amines as shown in Eq. (37) [45]. This ruthenium/peracid oxidation reaction provides an alternative to the Strecker reaction for the synthesis of a-amino acid derivatives since they involve the same a-cyano amine intermediates. In this way N-methyl-N-(p-methoxyphenyl) glycine could be prepared from N,N-dimethyl-p-methoxyaniline in 82% yield. 

The formation of the polymer complex was observed between poly-VAd and natural RNA. In order to get better information about the specific interaction between poly-VAd and RNA, further studies on the interaction of N-methyl and N,N-dimethyl derivatives of poly-VAd with RNA were carried out. It was found that mono- or dimethylation of the 6-amino group of poly-VAd depresses the specific polymer-polymer interaction, and no polymer complex was formed between the N,N-dimethyl derivative of poly-VAd and RNA. This fact suggests that the interaction between poly-VAd and RNA was caused by hydrogen bonding between the complementary nucleic add bases. 

Connnonly used peptide coupling agents may also be used for the conversion of activated carboxylic adds into esters. Treatment of N-protected amino acids or peptides with ethyl 2-ethoxy-l,2-dihydroquinoline-l-carboxylate (EEDQ) results in mixed anhydride intermediates that produce methyl esters in the presence of excess MeOH (solvent) at room temperature. The methyl esters are conveniently isolated by aqueous acid washing of the crude residue to remove the quinoline. 

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