Aspartic protease inhibitors: expedient synthesis of 2-substituted statines

Micromonosporamide A with Glutamine-Dependent Cytotoxicity from Micromonospora sp. MM609M-173N6: Isolation, Stereochemical Determination, and Synthesis

An acyldipeptide, micromonosporamide A, was isolated from the fermentation broth of Micromonospora sp. MM609M-173N6 by bioassay-guided fractionation using a glutamine compensation assay. The planar structure was elucidated on the basis of comprehensive one- and two-dimensional nuclear magnetic resonance and high-resolution mass spectrometry. The relative and absolute configuration of the entire molecule were determined using a combined approach, involving chromatographic analysis by liquid chromatography-mass spectrometry, advanced Marfey's method, and total synthesis. Micromonosporamide A exhibited glutamine-dependent antiproliferative activity.

General Inverse Solid-Phase Synthesis Method for C-Terminally Modified Peptide Mimetics

Peptide mimetics are of considerable interest as bioactive agents and drugs. C-terminally modified peptide mimetics are of particular interest given the synthetic versatility of the carboxyl group and its derivatives. A general approach to C-terminally modified peptide mimetics, based on a urethane attachment strategy and amino acid t-butyl ester-based N-to-C peptide synthesis, is described. This approach is compatible with the reaction conditions generally employed for solution-phase peptide mimetic synthesis. To develop and demonstrate this approach, it was employed for the solid-phase synthesis of peptide trifluoromethyl ketones, peptide boronic acids, and peptide hydroxamic acids. The development of a versatile general approach to C-terminally modified peptides using readily available starting materials provides a basis for the combinatorial and parallel solid-phase synthesis of these peptide mimetic classes for bioactive agent screening and also provides a basis for the further development of solid-phase C-terminal functional group elaboration strategies.

Solid-phase synthesis of HTLV-1 protease inhibitors containing hydroxyethylamine dipeptide isostere

An efficient method has been developed for the first solid-phase synthesis of HTLV-1 protease inhibitors that contain hydroxyethylamine isostere as a transition-state mimetic. The synthetic procedure was designed to allow the evaluation of stereostructure-activity relationships at the scissile site. All the possible configurations at the hydroxy- and side chain-bearing asymmetric centers of the isostere were constructed by an ester-derived asymmetric aldol reaction. Each inhibitor containing the isostere backbone was synthesized on solid support by using the newly developed succinate ester linker. The configuration at the hydroxy- and side chain-bearing asymmetric center showed remarkable effects on the inhibitory activity; the K(i) value changed with approximately 2 orders of magnitude. The described approach enables an efficient preparation of the inhibitors containing secondary alcohol as a transition-state mimetic.

Diastereoselective synthesis of new psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type alkene dipeptide isosteres by organocopper reagents and application to conformationally restricted cyclic RGD peptidomimetics

Diastereoselective synthesis of new psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type alkene dipeptide isosteres corresponding to dipeptides having one N-methylamino acid, and application to bioactive peptides, are described. In a key reaction introducing the chiral alpha-alkyl group of the isosteres, organocopper-mediated alkylation of syn-beta-methylated gamma-mesyloxy-alpha,beta-enoate 26a afforded E- and Z-isomers of anti-S(N)2' products in a solvent-dependent manner. The resulting two isosteres, D-Phe-psi[(E)-CH=CMe]-L-Val 27a and D-Phe-psi[(Z)-CH=CMe]-L-Val 28b, which corresponded to trans- and cis-conformers of D-Phe-L-MeVal, respectively, were utilized in a structure-activity relationship study on cyclic RGD peptides 1 and 2, in company with a psi[(E)-CH=CH]-type alkene dipeptide isostere, D-Phe-psi[(E)-CH=CH]-L-Val. The cyclic isostere-containing pseudopeptides 3, 4, and 40 were synthesized and biological activity against integrin alpha(V)beta(3) and alpha(IIb)beta(3) receptors were also evaluated.