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We have identified the N(1)-benzyl-N(2)-methylethane-1,2-diamine unit as a substitute for the (S)-alanine benzylamide moiety for the design of co-activator associated arginine methyltransferase 1 (CARM1) inhibitors. The potency of these inhibitors is in the same order of magnitude as their predecessors and their clearance, volume of distribution, and half lives were greatly improved.

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We have recently reported on a novel class of histone deacetylase (HDAC) inhibitors bearing a sulfamide group as the zinc-binding unit. Herein, we report on the synthesis of sulfamide based inhibitors designed around a lysine scaffold and their structure-activity relationships against HDAC1 and HDAC6 isotypes as well as 293T cells. Our efforts led us to an improvement of the originally disclosed lysine-based sulfamide, 2a to compound 12h which has equal potency in enzyme and cell-based assays as well as enhanced metabolic stability and PK profile.

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A series of N-benzyl-1-heteroaryl-3-(trifluoromethyl)-1H-pyrazole-5-carboxamides targeting co-activator associated arginine methyltransferase 1 (CARM1) have been designed and synthesized. The potency of these inhibitors was influenced by the nature of the heteroaryl fragment with the thiophene analogues being superior to thiazole, pyridine, isoindoline and benzofuran based inhibitors.

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In an effort to identify HDAC isoform selective inhibitors, we designed and synthesized novel, chiral 3,4-dihydroquinoxalin-2(1H)-one and piperazine-2,5-dione aryl hydroxamates showing selectivity (up to 40-fold) for human HDAC6 over other class I/IIa HDACs. The observed selectivity and potency (IC(50) values 10-200 nM against HDAC6) is markedly dependent on the absolute configuration of the chiral moiety, and suggests new possibilities for use of chiral compounds in selective HDAC isoform inhibition.

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The sulfamide moiety has been utilized to design novel HDAC inhibitors. The potency and selectivity of these inhibitors were influenced both by the nature of the scaffold, and the capping group. Linear long-chain-based analogs were primarily HDAC6-selective, while analogs based on the lysine scaffold resulted in potent HDAC1 and HDAC6 inhibitors.

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The biological activity of natural polyamines is due in large part to their ability to form ion-pairing interactions with polyanionic biomolecules, such as proteins, oligonucleotides, and sulfated oligosaccharides. Unfortunately, the diversity of biogenic polyamines is compromised by their limitation to only just a few internitrogen spacers. As a proof-of-principle study, a synthetic split-pool library of linear triamines was screened in an on-bead assay against a selection of model trisulfonated azo dyes (1, 2, and 3) and a short glutamate-rich nonameric peptide (4) to demonstrate its use in the discovery of selective ligands via multivalent ion pairing. From screening a 196-membered split-pool library against the dyes in aqueous organic solutions, with or without spermidine as competing ligand, it was found that the most frequent residues possessed internitrogen distances that were very similar to the sulfonate distances on the dyes. The results from these screening assays were used in the design of two polyamine sequences (8, 8Aoc(R)-8Aoc(R), and 12, 2Acc(R)-epsilonAhx(R)) for follow-up studies in solution phase. These triamines demonstrated the same selectively toward dyes 2 and 3 as observed by the solid-phase approach. In addition, resin-supported triamines, synthesized as discrete compounds, were able to selectively extract either dye 2 or 3 from a mixture of the two, further verifying the observations made from the library screening efforts. With peptide 4, containing three glutamate residues, a preference was found for rather long residues (12 and 8 carbons long), which is suggestive of a linear peptide, rather than a helical motif under the conditions of the screening.

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Simple HPLC experiments were used to identify a redundant tagging scheme wherein six different amino acids were tagged with only four fluorous tags. The tagged amino acids were converted to regiosiomeric mixtures of tricyclic hydantoins. Despite the lack of selectivity, the mixtures were demixed and detagged to give 11 individual pure products in just 25 steps.

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Fluorous mixture synthesis was used to prepare a library of 4-alkylidene cyclopentenones starting from a mixture of four alpha-amino acid derivatives tagged with different fluorous benzyl carbamates ((F)CBz) of varying fluorine content. The amino acids were converted to the corresponding propargyl esters and then subjected to an ester-enolate Claisen rearrangement to give a mixture of allenic amino esters. The allenes were then split four ways and propargylated with different propargyl bromides to give four mixtures of alkynyl allenes. The 4-alkylidene cyclopentenones were formed by a formal [2+2+1] cycloaddition of the alkynyl allenes using catalytic [Rh(CO)2Cl]2 under CO atmosphere. Demixing by fluorous preparative HPLC, removal of the fluorous benzyl carbamates, and then exposure to HCl/ether gave the hydrochloride salts of 16 compounds as diastereomeric mixtures in 69-99% purity. Thus, after just 26 chemical steps, a library of 16 cyclopentenones was prepared by using fluorous mixture synthesis. By comparison, the same library would have required 112 steps if each compound were made individually by parallel synthesis.

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This article describes the design and optimization of the first entirely modular, parallel solid-phase synthetic approach for the generation of well-defined polyamine oligoboronic acid receptors and fluorescence sensors for complex oligosaccharides. The synthetic approach allows an effective building of the receptor polyamine backbone, followed by the controlled diversification of the amine benzylic side chains. This approach enabled the testing, in a modular fashion, of the effect of different arylboronic acid units substituted with unencumbering para electron-withdrawing or electron-donating groups. The feasibility of this approach toward automated synthesis was also investigated with the assembly of a sublibrary of receptors by means of the Irori MiniKan technology. Several sublibraries of anthracene-capped sensors containing two or three arylboronic acids were synthesized, and their binding to a series of model disaccharides was examined in neutral aqueous media. The calculation of association constants by fluorescence titrations confirmed that subtle changes in the structures of the interamine spacers in the polyamine backbone can have a significant effect on the stability of the resulting complexes. Most importantly, this study led to the determination of the preferred electronic characteristics for the arylboronate units, and suggests that a new generation of receptors containing very electron-poor arylboronic acids could lead to a significant improvement of binding affinities.

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Natural polyamines are ubiquitous biomolecules present in all living cells. These cationic compounds play essential roles in both cell growth and differentiation and are known to interact in complex ways with polyanionic biomolecules. Consequently, there is significant interest in expanding nature's polyamine diversity using combinatorial synthesis and screening strategies. This article describes an efficient split-pool solid-phase synthetic strategy toward the generation of encoded libraries of polyamines via the exhaustive borane-promoted reduction of trityl-linked, resin-bound polyamides. Model structural libraries of tetra- and pentaamines were designed from a set of geometrically diverse amino acid building blocks. To encode the libraries, a partial termination synthesis approach was employed at the polyamide stage, allowing each library to be analyzed from single beads by HPLC/ESMS under two sets of conditions featuring both pH extremes. Determination of the sequence of polyamine residues was simply achieved by the mass differences observed between the full oligomers and the terminated ones. Both polystyrene- and TentaGel-supported libraries, including a library of 4913 pentaamines, were prepared and successfully decoded. For the TentaGel-supported libraries, suitable for on-bead aqueous screening of biomolecules, a novel trityl-derivatized resin was prepared in which the trityl group is anchored to the poly(ethylene glycol) chains via a methylene group. The resulting resin is much more resistant than other commercially available polystyrene-poly(ethylene glycol) trityl resins to the harsh borane reduction conditions required. Two workup conditions for the cleavage of the resultant borane-amine adducts were evaluated on the TentaGel bound polyamide 14. Although the two methods showed a comparable efficiency when using the polystyrene support, with 14 it was found that the piperidine-exchange method afforded polyamines of higher purity than the iodine-based oxidative method previously developed in our laboratory.

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[structure: see text] Screening of a bead-supported encoded library of unnatural polyamines against model polyanionic targets (1 and 2) demonstrated that a combinatorial approach can highlight structural selectivity in multivalent ion pairing in aqueous solutions. This approach even provided -NH-2Acc(R)-6Ahx(R)-Et, a highly target-selective triamine sequence that can discriminate between two trisulfonated dyes displaying subtle structural differences.

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