Two distinct classes of novel pyrazolinecarboxamides as potent cannabinoid CB1 receptor agonists.

The synthesis and SAR of 3-alkyl-4-aryl-4,5-dihydropyrazole-1-carboxamides 1-23 and 1-alkyl-5-aryl-4,5-dihydropyrazole-3-carboxamides 24-27 as two novel cannabinoid CB(1) receptor agonist classes were described. The target compounds elicited high affinities to the CB(1) as well as the CB(2) receptor and were found to act as CB(1) receptor agonists. The key compound 19 elicited potent CB(1) agonistic and CB(2) inverse agonistic properties in vitro and showed in vivo activity in a rodent model for multiple sclerosis after oral administration.

Synthesis, SAR and intramolecular hydrogen bonding pattern of 1,3,5-trisubstituted 4,5-dihydropyrazoles as potent cannabinoid CB(1) receptor antagonists.

The synthesis, structure-activity relationship (SAR) studies and intramolecular hydrogen bonding pattern of 1,3,5-trisubstituted 4,5-dihydropyrazoles are described. The target compounds 6-18 represent a novel class of potent and selective CB(1) receptor antagonists. Based on X-ray diffraction data, the orally active 17 is shown to elicit a different intramolecular H-bonding mode as compared to ibipinabant (3) and SLV330 (4).

Synthesis and SAR of novel imidazoles as potent and selective cannabinoid CB2 receptor antagonists with high binding efficiencies.

The synthesis and structure-activity relationship studies of imidazoles are described. The target compounds 6-20 represent a novel chemotype of potent and CB(2)/CB(1) selective cannabinoid CB(2) receptor antagonists/inverse agonists with very high binding efficiencies in combination with favourable logP and calculated polar surface area values. Compound 12 exhibited the highest CB(2) receptor affinity (K(i)=1.03 nM) in this series, as well as the highest CB(2)/CB(1) subtype selectivity (>9708-fold).

Novel 3,4-diarylpyrazolines as potent cannabinoid CB1 receptor antagonists with lower lipophilicity.

Novel 3,4-diarylpyrazolines 1 as potent CB1 receptor antagonists with lipophilicity lower than that of SLV319 are described. The key change is the replacement of the arylsulfonyl group in the original series by a dialkylaminosulfonyl moiety. The absolute configuration (4S) of eutomer 24 was established by X-ray diffraction analysis and 24 showed a close molecular fit with rimonabant in a CB1 receptor-based model. Compound 17 exhibited the highest CB1 receptor affinity (Ki = 24 nM) in this series, as well as very potent CB1 antagonistic activity (pA2 = 8.8) and a high CB1/CB2 subtype selectivity (approximately 147-fold).

Bioisosteric replacements of the pyrazole moiety of rimonabant: synthesis, biological properties, and molecular modeling investigations of thiazoles, triazoles, and imidazoles as potent and selective CB1 cannabinoid receptor antagonists.

Series of thiazoles, triazoles, and imidazoles were designed as bioisosteres, based on the 1,5-diarylpyrazole motif that is present in the potent CB(1) receptor antagonist rimonabant (SR141716A, 1). A number of target compounds was synthesized and evaluated in cannabinoid (hCB(1) and hCB(2)) receptor assays. The thiazoles, triazoles, and imidazoles elicited in vitro( )()CB(1) antagonistic activities and in general exhibited considerable CB(1) vs CB(2) receptor subtype selectivities, thereby demonstrating to be cannabinoid bioisosteres of the original diarylpyrazole class. Some key representatives in the imidazole series showed potent pharmacological in vivo activities after oral administration in both a CB agonist-induced hypotension model and a CB agonist-induced hypothermia model. Molecular modeling studies showed a close three-dimensional structural overlap between the key compound 62 and rimonabant. A structure-activity relationship (SAR) study revealed a close correlation between the biological results in the imidazole and pyrazole series.

Synthesis, biological properties, and molecular modeling investigations of novel 3,4-diarylpyrazolines as potent and selective CB(1) cannabinoid receptor antagonists.

A series of novel 3,4-diarylpyrazolines was synthesized and evaluated in cannabinoid (hCB(1) and hCB(2)) receptor assays. The 3,4-diarylpyrazolines elicited potent in vitro CB(1) antagonistic activities and in general exhibited high CB(1) vs CB(2) receptor subtype selectivities. Some key representatives showed potent pharmacological in vivo activities after oral dosing in both a CB agonist-induced blood pressure model and a CB agonist-induced hypothermia model. Chiral separation of racemic 67, followed by crystallization and an X-ray diffraction study, elucidated the absolute configuration of the eutomer 80 (SLV319) at its C(4) position as 4S. Bioanalytical studies revealed a high CNS-plasma ratio for the development candidate 80. Molecular modeling studies showed a relatively close three-dimensional structural overlap between 80 and the known CB(1) receptor antagonist rimonabant (SR141716A). Further analysis of the X-ray diffraction data of 80 revealed the presence of an intramolecular hydrogen bond that was confirmed by computational methods. Computational models and X-ray diffraction data indicated a different intramolecular hydrogen bonding pattern in the in vivo inactive compound 6. In addition, X-ray diffraction studies of 6 revealed a tighter intermolecular packing than 80, which also may contribute to its poorer absorption in vivo. Replacement of the amidine -NH(2) moiety with a -NHCH(3) group proved to be the key change for gaining oral biovailability in this series of compounds leading to the identification of 80.