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Cancer is a chronic degenerative disease considered one of the most important causes of death worldwide. In this context, a series of dual-protected amino acid derivatives was synthesized and evaluated as potential novel anticancer agents. The 40 derivatives were prepared in up to three reaction steps. The cytotoxic activities were screened in vitro against a panel of tumor and non-tumor cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Among the synthesized derivatives, three of them showed promising activity against cancer cells with half-maximal inhibitory concentration (IC50) ranging between 1.7-6.1 μM. The most promising derivative, bearing both a lipophilic N-alkyl diamine moiety and a protected amino acid scaffold showed a selectivity index of 3.4 towards tumor cells. The N-alkyl diamine moiety seems to play a crucial role in the enhancement of the anticancer activity. On the other hand, the incorporation of an amino acid scaffold resulted in increase in the selectivity towards cancer cell lines.

Tuberculosis is an infectious disease with high incidence and growing drug-resistant rates. In an attempt to develop new antitubercular agents, 35 compounds were synthesized, most of them bearing a carbamate and enantiopure amino acid moiety. These compounds had their activity evaluated toward a Mycobacterium tuberculosis strain (ATCC 27294) and cytotoxicity against fibroblast MRC-5 cells (ATCC CCL-171). Three of the prepared derivatives presented a good antimicrobial inhibition and two of them a moderate cytotoxicity. The lipophilicity seems to play a vital role in the cell growth activity, with best results for the derivatives with a higher logP.

B(OCH2CF3)3, prepared from readily available B2O3 and 2,2,2-trifluoroethanol, is as an effective reagent for the direct amidation of a variety of carboxylic acids with a broad range of amines. In most cases, the amide products can be purified by a simple filtration procedure using commercially available resins, with no need for aqueous workup or chromatography. The amidation of N-protected amino acids with both primary and secondary amines proceeds effectively, with very low levels of racemization. B(OCH2CF3)3 can also be used for the formylation of a range of amines in good to excellent yield, via transamidation of dimethylformamide.

Formation of carboxamides of a variety of carboxylic acids with the coupling reagent BBDI is described. This procedure permits a one pot and simple operation without the need of any bases and no base was?required for even use of amine hydrochlorides. In addition, an approach to BBDI-catalyzed carboxamidation is examined.

Simple, highly modular primary amino acid derivatives catalyze the direct enantioselective addition of ketones to nitro-olefins with high stereocontrol and furnish the corresponding aldol products in high yield with up to >38 : 1 dr and up to 99% ee. The

Isophthalic acid bis(L-prolyl-pyrrolidine) amide is a very potent prolyl oligopeptidase inhibitor, but it has a log P value of -0.2, which is very low for a compound targeted to the brain. Therefore, these types of compounds were further modified to improve the structure-activity relationships, with the focus on increasing the log P value. The inhibitory activity against prolyl oligopeptidase from pig brain was tested in vitro. The most promising compounds resulted from replacing the pyrrolidinyl group at the P5 site by cycloalkyl groups, such as cyclopentyl and cyclohexyl groups, and by a phenyl group. These compounds are slightly more potent, and they have a significantly higher log P value. The potency of these compounds was further increased by replacing the pyrrolidinyl group at the P1 site by 2(S)-cyanopyrrolidinyl and 2(S)-(hydroxyacetyl)pyrrolidinyl groups.

In this paper we report the systematic search for new, potent, and selective DPP II inhibitors. A study of the structure-activity relationship was conducted starting from aminoacyl pyrrolidides as lead compounds. Rational exploration of the P1

By synthesizing and testing a part-structure, N-[2-(3,4- dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine (3), derived from our previously reported high affinity σ receptor ligands (1S,2R)-(-)-N-[2- (3,4-dichlorophenyl)-ethyl]-N-methyl-2-(1-pyrrolidinyl)cyclohexylamine [(-)- 2] and (+)-2, we have identified a novel class of superpotent (subnanomolar affinity) σ ligands specific for the σ receptor labeled by [3H]-(+)-3-PPP. When 3 was tested for its capacity to displace [3H]-(+)-3-PPP from guinea pig brain membranes, it exhibited a K(i) of 0.34 nM, which is better than either of its parent compounds (-)-2 (K(i) = 1.3 nM) and (+)-2 (K(i) = 6.0 nM). Other compounds related to 3 such as N-[2-(3,4-dichlorophenyl)ethyl]-N- methyl-2-(1-homopiperidinyl)ethylamine (19) exhibited K(i) = 0.17 nM ([3H]- (+)-3-PPP). The determinants for high σ receptor affinity of 3 were examined by manipulation of this structure in a number of different ways. The high efficacy of these compounds for the σ receptor, their relative chemical simplicity and ease of synthesis, and their high degree of selectivity identifies N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1- pyrrolidinyl)ethylamine (3) and related compounds as a highly promising base for determination of the functional role of σ receptors as well as the development of novel therapeutic agents.