Synthesis of resin 20 for preparation of library C The loading procedure described above for the preparation of libraries A and B was used without any significant modifications. cells overexpressing 17-HSD1 of the estradiol derivatives carrying different oligoamide-type chains at C-16 first revealed that three levels of molecular diversity (a spacer of two amino acids) were necessary to interact with the adenosine part of the cofactor binding site. Second, the best inhibition was obtained when hydrophobic residues (phenylalanine) were used as building blocks. (Scheme 2) EIF4G1 For library C members, capping with an amine functional group was chosen to interact with the cofactor (adenosine) binding site. For this purpose, aniline derivatives were chosen. In order to obtain optimal interactions with the cofactor-binding site of the enzyme, carboxylic acid with several alkyl spacer KIN-1148 lengths (n = 0 to 3 methylenes) was chosen. Aniline derivatives 9C10 with a spacer of two methylenes were not commercially available, but were prepared easily in one step from 4-aminocinnamic acid or 3-nitrocinnamic acid, respectively, as previously reported . In order to avoid polymerisation during the capping coupling step on solid-phase organic synthesis, free anilines 7C11 were protected as Fmoc using FmocOSu and NaHCO3 in a mixture THF/H2O (5:1) to provide 14C18 in good yields (51C93%). It is noteworthy to mention that Fmoc-aniline derivatives 12C13 were commercially available. 2.3. Solid-phase synthesis of libraries A, B and C (Scheme 3) A library of 30 sulfamoylated E2 derivatives (A), a library of 30 E2 derivatives (B), and a library of 63 E2 derivatives (C) were prepared by parallel solid-phase synthesis using the multidetachable linker sulfamate. Precursor 6a was first loaded on trityl chloride resin. For this reaction, trityl chloride resin was swelled in dry DCM and treated with 6a and diisopropylethylamine (DIPEA) in a peptide flask. After 16 h of shaking, the reaction mixture was filtered and washed with DCM and MeOH to obtain resin 19. The loading yield of 19 was calculated by the KIN-1148 increase of the resin weight. This yield was 70% for libraries A and B and 42% for library C. A lower loading yield was obtained for library C because 1 equivalent of 6a was used for 2 equivalents of trityl chloride resin instead of 1 equivalent of resin used in the preparation of libraries A and B. On a model library with a loading of 75%, completion of the coupling reaction was very difficult for the introduction of the third level of molecular diversity. It was hypothesized that steric KIN-1148 hindrance could be responsible for the lower reactivity of the amine on the steroid. Therefore, less precursor 6a was loaded on resin when more than two levels of molecular diversity needed to be introduced on the steroid. In the next step, resin 19 was treated for 1 h with a freshly prepared solution of 20% piperidine in DCM to remove the Fmoc protective group and to free the amine for the next step. It is noteworthy to mention that after each solid-phase organic step, the resin was washed with the appropriate solvent and dried under a vacuum. Furthermore, the solid-phase reactions were monitored by a mini-cleavage test of a random sampling of resin with 5% TFA in DCM. The resin 20 was next split into 30 equal portions for libraries A and B and 63 equal portions for library C. The resins were then placed in bottom fritted reaction vessels of a 96 solid-phase reaction block of an ACT-Labtech semi-automated synthesizer..
Synthesis of resin 20 for preparation of library C The loading procedure described above for the preparation of libraries A and B was used without any significant modifications
- by globalhealth