SAR studies of 6-(arylamino)-4,4-disubstituted-1-methyl-1,4-dihydro-benzo[d][1,3]oxazin-2-ones as progesterone receptor antagonists

We previously disclosed that 6-aryl benzoxazin-2-ones were PR modulators. In a continuation of this work we examined the SAR of new 6-arylamino benzoxazinones and found the targets 1-25, with an extra amino linker between the pendent 6-aryl groups and benzoxazinone or benzoxazine-2-thione core, were PR antagonists. A series of compounds with substituents at the 1- and 4-positions as well as different 6-aryl groups were prepared and tested in the T47D cell alkaline phosphatase assay. Interestingly, the SAR unveiled from the 6-arylamino benzoxazinones was quite different from those of their parent compounds. For example, in contrast to the 6-aryl benzoxazinones, methyl substitution at the 1-position significantly increased the potency of 6-arylamino benzoxazinones. Several 6-arylamino benzoxazinones (e.g., 12, IC(50)=5.0 nM) had low nanomolar in vitro potency as PR antagonists in the T47D cell alkaline phosphatase assay.     

2-Benzenesulfonyl-8a-benzyl-hexahydro-2H-isoquinolin-6-ones as selective glucocorticoid receptor antagonists

The 2-azadecalin ring system was evaluated as a scaffold for the preparation of glucocorticoid receptor (GR) antagonists. High affinity, selective GR antagonists were discovered based on a hypothetical binding mode related to the steroidal GR antagonist RU-43044. 2-Benzenesulfonyl substituted 8a-benzyl-hexahydro-2H-isoquinolin-6-ones exemplified by (R)-37 had low nanomolar affinity for GR with moderate functional activity (200 nM) in a reporter gene assay. These compounds were devoid of affinity for other steroidal receptors (ER, AR, MR, and PR). Analogues based on an alternative putative binding mode (CP-like) were found to be inactive.     

SAR studies of novel 5-substituted 2-arylindoles as nonpeptidyl GnRH receptor antagonists

The discovery of the potency-enhancing effect of 5-substitutions on the novel 2-arylindoles as nonpeptidyl GnRH receptor antagonists led to the identification of several analogues with high affinities on the GnRH receptor. The syntheses and SARs of these 5-substituted-2-arylindole analogues are reported.     

Array synthesis of progesterone receptor antagonists: 3-aryl-1,2-diazepines

New non-steroidal chemotypes are required for the development of drugs targeting the steroid hormone receptors. The parallel array synthesis of 3-aryl-1,2-diazepines employing solid-supported reagents is described. The resulting compounds demonstrated high affinity binding to the progesterone receptor.     

Synthesis and SAR study of novel pseudo-steroids as potent and selective progesterone receptor antagonists

Synthesis of novel 7-pseudo-steroids 1c has been achieved from trenbolone 3 via an efficient 14 step sequence with overall yields of 10–15%. Various substitutions were incorporated at both the aromatic side chain as well as the D ring. The orientation of aromatic side chain at C10 plays a crucial role for progesterone receptor (PR) activity. Compound 2a (T47D = 1 nM) with –NMe₂ para to the aromatic group along with spirofurane groups in the D ring was the optimal substitution. All compounds were also evaluated for glucocorticoid receptor (GR) antagonist activities in vivo in a rat and found efficacious in uterine complement C3 assay via the oral route of administrations.     

Selective alpha1a adrenergic receptor antagonists based on 4-aryl-3,4-dihydropyridine-2-ones

A series of alpha1a receptor antagonists derived from a 4-aryl-3,4-dihydropyridine-2-one heterocycle is disclosed. Potency in the low nanomolar to picomolar range along with high selectivity was obtained. In vivo efficacy in a prostate contraction model in rats was observed with a few derivatives.     

Parallel synthesis and SAR study of novel oxa-steroids as potent and selective progesterone receptor antagonists

Efficient parallel synthesis of novel 7-oxa-steroids 4 has been achieved from the key intermediate 3 via a one-pot four-step sequence. oxa-Steroids 4 with various ortho-, meta-, and para-monosubstituents on the phenyl ring, as well as disubstituted phenyl and heterocycles, were evaluated for progesterone receptor (PR) and glucocorticoid receptor (GR) antagonist activities. SAR study demonstrated that the para-fluorinated substituents on the phenyl ring not only increased the potency for PR in a T47D cell functional assay, but also improved the selectivity over GR in an A549 cell functional assay. The para-fluorophenyl oxa-steroid 4l and the para-trifluoromethylphenyl oxa-steroid 4p were found to be remarkably more potent and more selective PR antagonists than mifepristone, with subnanomolar potency and about 140-fold selectivity over GR. Molecular modeling of the oxa-steroid bound to PR provided meaningful insight for the SAR study. oxa-Steroids 4a and 4b were found to be more efficacious than mifepristone in vivo in a rat uterine complement C3 assay via the oral route, although they were less than or equally potent to mifepristone in the T47D assay.     

Novel 5-aryl-1,3-dihydro-indole-2-thiones. potent,orally active progesterone receptor agonists

During the course of our studies on 3,3-disubstituted-5-aryloxindoles derived progesterone receptor (PR) antagonists we discovered that changing the amide funtionality to a thio-amide resulted in compounds displaying potent PR agonist activity. In this communication, the synthesis, structure activity relationships (SAR) and in vivo activity of various 5-arylthio-oxindoles will be discussed.     

7-aryl 1,5-dihydro-benzo[e][1,4]oxazepin-2-ones and analogs as non-steroidal progesterone receptor antagonists

Novel 7-aryl benzo[1,4]oxazepin-2-ones were synthesized and evaluated as non-steroidal progesterone receptor (PR) modulators. The structure activity relationship of 7-aryl benzo[1,4]oxazepinones was examined using the T47D cell alkaline phosphatase assay. A number of 7-aryl benzo[1,4]oxazepinones such as 10j and 10v demonstrated good in vitro potency (IC(50) of 10-30 nM) and selectivity (over 100-fold) at PR over other steroidal receptors such as glucocorticoid and androgen receptors (GR and AR). Several 7-aryl benzo[1,4]oxazepinones were active in the rat uterine decidualization model. In this in vivo model, compounds 10j and 10u were active at 3 mg/kg when dosed orally.     

8-alkylthio-6-thio-substituted theophylline analogues as selective noncompetitive progesterone receptor antagonists

The progesterone receptor (PR) plays a key role in reproduction and is important in cancers of the reproductive tract. Current PR antagonists usually compete for progestin binding in the PR ligand-binding pocket and often exhibit cross-binding with other members of the steroid receptor family. Using stably transfected cells expressing reporter genes, a set of ～150 theophylline analogues were screened for their ability to inhibit progesterone, estrogen, glucocorticoid and androgen signaling. The structure-activity studies presented here identify branched 8-alkylthio-6-thio-substitutions of theophylline as selective PR inhibitors. 6-Thio-8-(2-ethylbutyl)thiotheophylline (51), the most extensively studied derivative, does not act by competing with progestins for binding in the ligand-binding pocket of PR. It demonstrated the ability to inhibit the mouse mammary tumor virus (MMTV)-luciferase reporter and endogenous PR-regulated alkaline phosphatase activity in T47D breast cancer cells. Compound 51 is the lead member of a novel class of PR inhibitors that act outside the PR ligand-binding pocket, thus serving as a novel probe to investigate PR action and a lead for further development.     

Nonsteroidal progesterone receptor antagonists based on 6-thiophenehydroquinolines

Synthesis and biological evaluation of 6-thiophene 1,2-dihydro or 1,2,3,4-tetrahydroquinoline derivatives resulted in a number of potent nonsteroidal antiprogestins.     

SAR studies of 1,5-diarylpyrazole-based CCK1 receptor antagonists

A high throughput screening campaign revealed compound 1 as a potent antagonist of the human CCK(1) receptor. Here, we report the syntheses and SAR studies of 1,5-diarylpyrazole analogs with various structural modifications of the alkane side chain of the molecule. The difference in affinity between the two enantiomers for the CCK(1) receptor and the flexible nature of the linker led to the design of constrained analogs with increased potency.     

Synthesis and SAR studies of novel 2-(6-aminomethylaryl-2-aryl-4-oxo-quinazolin-3(4H)-yl)acetamide vasopressin V1b receptor antagonists

Synthesis and structure-activity relationships (SAR) of a novel series of vasopressin V_1b antagonists are described. 2-(6-Aminomethylaryl-2-aryl-4-oxo-quinazolin-3(4H)-yl)acetamide have been identified with low nanomolar affinity for the V_1b receptor and good selectivity with respect to related receptors V_1a, V₂ and OT. Optimised compound 16 shows a good pharmacokinetic profile and activity in a mechanistic model of HPA dysfunction.     

Synthesis and SAR studies of trisubstituted purinones as potent and selective adenosine A2A receptor antagonists

A series of trisubstituted purinones was synthesized and evaluated as A_2A receptor antagonists. The A_2A structure–activity relationships at the three substituted positions were studied and selectivity against the A₁ receptor was investigated. One antagonist 12o exhibits a K_i of 9 nM in an A_2A binding assay, a K_b of 18 nM in an A_2A cAMP functional assay, and is 220-fold selective over the A₁ receptor.     

Synthesis and SAR of 1,3-disubstituted cyclohexylmethyl urea and amide derivatives as non-peptidic motilin receptor antagonists

A series of 1,3-disubstituted cyclohexylmethyl urea and amide derivatives were synthesized as motilin receptor antagonists. Starting from known motilin antagonists, 1a and 1b, the cyclopentene scaffold was replaced and the four recognition elements optimized to arrive at a potent novel series.     

Synthesis and SAR studies of chiral non-racemic dexoxadrol analogues as uncompetitive NMDA receptor antagonists

A series of chiral non-racemic dexoxadrol analogues with various substituents in position 4 of the piperidine ring was synthesized and pharmacologically evaluated. Only the enantiomers having (S)-configuration at the 2-position of the piperidine ring and 4-position of the dioxolane ring were considered. Key steps in the synthesis were an imino-Diels-Alder reaction of enantiomerically pure imine (S)-13, which had been obtained from d-mannitol, with Danishefsky's Diene 14 and the replacement of the p-methoxybenzyl protective group with a Cbz-group. It was shown that (S,S)-configuration of the ring junction (position 2 of the piperidine ring and position 4 of the dioxolane ring) and axial orientation of the C-4-substituent ((4S)-configuration) are crucial for high NMDA receptor affinity. 2-(2,2-Diphenyl-1,3-dioxolan-4-yl)piperidines with a hydroxy moiety ((S,S,S)-5, K(i)=28nM), a fluorine atom ((S,S,S)-6, WMS-2539, K(i)=7nM) and two fluorine atoms ((S,S)-7, K(i)=48nM) in position 4 represent the most potent NMDA antagonists with high selectivity against σ(1) and σ(2) receptors and the polyamine binding site of the NMDA receptor. The NMDA receptor affinities of the new ligands were correlated with their electrostatic potentials, calculated gas phase proton affinities (negative enthalpies of deprotonation) and dipole moments. According to these calculations decreasing proton affinity and increasing dipole moment are correlated with decreasing NMDA receptor affinity.     

Discovery and expanded SAR of 4,4-disubstituted quinazolin-2-ones as potent T-type calcium channel antagonists

The discovery and synthesis of 4,4-disubstituted quinazolinones as T-type calcium channel antagonists is reported. Based on lead compounds 2 and 3, a focused SAR campaign driven by the optimization of potency, metabolic stability, and pharmacokinetic profile identified 45 as a potent T-type Ca²⁺ channel antagonist with minimized PXR activation. In vivo, 45 suppressed seizure frequency in a rat model of absence epilepsy and showed significant alterations of sleep architecture after oral dosing to rats as measured by EEG.     

Synthesis and SAR of 1,2,3,4-tetrahydroisoquinolin-1-ones as novel G-protein-coupled receptor 40 (GPR40) antagonists

The development of a series of novel 1,2,3,4-tetrahydroisoquinolin-1-ones as antagonists of G protein-coupled receptor 40 (GPR40) is described. The synthesis, in vitro inhibitory values for GPR40, in vitro microsomal clearance and rat in vivo clearance data are discussed. Initial hits displayed high rat in vivo clearances that were higher than liver blood flow. Optimization of rat in vivo clearance was achieved and led to the identification of 15i, whose rat oral pharmacokinetic data is reported.     

Isoquinoline derivatives as potent CRTH2 receptor antagonists: synthesis and SAR

Synthesis and structure-activity relationship of a novel series of isoquinoline CRTH2 receptor antagonists are described. One of the most potent compounds, TASP0376377 (6m), showed not only potent binding affinity (IC(50)=19 nM) but also excellent functional antagonist activity (IC(50)=13 nM). TASP0376377 was tested for its ability of a chemotaxis assay to show the effectiveness (IC(50)=23 nM), which was in good agreement with the CRTH2 antagonist potency. Furthermore, TASP0376377 showed sufficient selectivity for binding to CRTH2 over the DP1 prostanoid receptor (IC(50)>1 μM) and COX-1 and COX-2 enzymes (IC(50)>10 μM).     

Chain-branched 1,3-dibenzylthioureas as vanilloid receptor 1 antagonists

A series of chain-branched 1,3-dibenzylthiourea derivatives were synthesized, and tested their antagonist activity against vanilloid receptor 1. Chain-branching led to a significant change in the mode of action and the potency. (R)-Methyl or ethyl-branched 1,3-dibenzylthiourea derivatives showed the most potent antagonist activity up to the IC(50) value of 0.05 microM which is 10-fold more potent than capsazepine.