Design, synthesis and biological evaluation of renin inhibitors guided by simulated annealing of chemical potential simulations.

We have applied simulated annealing of chemical potential (SACP) to a diverse set of ∼150 very small molecules to provide insights into new interactions in the binding pocket of human renin, a historically difficult target for which to find low molecular weight (MW) inhibitors with good bioavailability. In one of its many uses in drug discovery, SACP provides an efficient, thermodynamically principled method of ranking chemotype replacements for scaffold hopping and manipulating physicochemical characteristics for drug development. We introduce the use of Constrained Fragment Analysis (CFA) to construct and analyze ligands composed of linking those fragments with predicted high affinity. This technique addresses the issue of effectively linking fragments together and provides a predictive mechanism to rank order prospective inhibitors for synthesis. The application of these techniques to the identification of novel inhibitors of human renin is described. Synthesis of a limited set of designed compounds provided potent, low MW analogs (IC50s<100nM) with good oral bioavailability (F>20-58%).

Discovery of novel aminoquinazolin-7-yl 6,7-dihydro-indol-4-ones as potent, selective inhibitors of heat shock protein 90.

A novel class of Hsp90 inhibitors, structurally distinct from previously reported scaffolds, was developed from rational design and optimization of a compound library screen hit. These aminoquinazoline derivatives, represented by compound 15 (SNX-6833) or 1-(2-amino-4-methylquinazolin-7-yl)-3,6,6-trimethyl-6,7-dihydro-1H-indol-4(5H)-one, selectively bind to Hsp90 and inhibit its cellular activities at concentrations as low as single digit nanomolar.

Application of chemoproteomics to drug discovery: identification of a clinical candidate targeting hsp90.

A chemoproteomics-based drug discovery strategy is presented that utilizes a highly parallel screening platform, encompassing more than 1000 targets, with a focused chemical library prior to target selection. This chemoproteomics-based process enables a data-driven selection of both the biological target and chemical hit after the screen is complete. The methodology has been exemplified for the purine binding proteome (proteins utilizing ATP, NAD, FAD). Screening of an 8000 member library yielded over 1500 unique protein-ligand interactions, which included novel hits for the oncology target Hsp90. The approach, which also provides broad target selectivity information, was used to drive the identification of a potent and orally active Hsp90 inhibitor, SNX-5422, which is currently in phase 1 clinical studies.

Discovery of novel 2-aminobenzamide inhibitors of heat shock protein 90 as potent, selective and orally active antitumor agents.

A novel class of heat shock protein 90 (Hsp90) inhibitors was developed from an unbiased screen to identify protein targets for a diverse compound library. These indol-4-one and indazol-4-one derived 2-aminobenzamides showed strong binding affinity to Hsp90, and optimized analogues exhibited nanomolar antiproliferative activity across multiple cancer cell lines. Heat shock protein 70 (Hsp70) induction and specific client protein degradation in cells on treatment with the inhibitors supported Hsp90 inhibition as the mechanism of action. Computational chemistry and X-ray crystallographic analysis of selected member compounds clearly defined the protein-inhibitor interaction and assisted the design of analogues. 4-[6,6-Dimethyl-4-oxo-3-(trifluoromethyl)-4,5,6,7-tetrahydro-1H-indazol-1-yl]-2-[(trans-4-hydroxycyclohexyl)amino]benzamide (SNX-2112, 9) was identified as highly selective and potent (IC(50) Her2 = 11 nM, HT-29 = 3 nM); its prodrug amino-acetic acid 4-[2-carbamoyl-5-(6,6-dimethyl-4-oxo-3-trifluoromethyl-4,5,6,7-tetrahydro-indazol-1-yl)-phenylamino]-cyclohexyl ester methanesulfonate (SNX-5422, 10) was orally bioavailable and efficacious in a broad range of xenograft tumor models (e.g. 67% growth delay in a HT-29 model) and is now in multiple phase I clinical trials.

A new synthesis of the ORL-1 antagonist 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidinyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J-113397) and activity in a calcium mobilization assay.

A new chiral synthesis of the ORL-1 antagonist 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidinyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (2, J-113397) was developed. J-113397 has a K(e)=0.85nM in an ORL-1 calcium mobilization assay and is 89-, 887-, and 227-fold selective for the ORL-1 receptor relative to the mu, delta, and kappa opioid receptors.

Synthesis of nicotine derivatives via reductive disilylation of (S)-nicotine.

[reaction: see text] A variety of novel nicotine derivatives were prepared via reductive disilylation of (S)-nicotine. Treatment of nicotine with lithium powder and chlorotrimethylsilane afforded 1,4-bis(trimethylsilyl)-1,4-dihydronicotine in high yield. Addition of various carbonyl electrophiles and a catalytic amount of TBAF provided either C-5 substituted nicotines or 1,4-dihydronicotine derivatives.

Regioselective C-2 and C-6 substitution of (S)-nicotine and nicotine derivatives.

[reaction: see text] Regioselective deprotonations of (S)-nicotine and derivatives at the C-2 and C-6 positions of the pyridine ring were performed in good to excellent yields. These methodologies allow the direct introduction of a plethora of functional groups onto the pyridine ring of nicotine.

Synthesis of C-4 substituted nicotine derivatives via an N-acylpyridinium salt of (S)-nicotine.

[reaction: see text] A variety of novel nicotine derivatives were prepared from (S)-nicotine via a two-step sequence. Addition of a cuprate reagent to an N-acylpyridinium salt of nicotine, followed by aromatization with elemental sulfur, afforded C-4 substituted nicotines in moderate to high yield. Using this method, 4-(dimethylphenylsilyl)nicotine was prepared and oxidized to afford (S)-4-hydroxynicotine.