Aminoalkyl phenyl sulfones--a novel series of 5-HT7 receptor ligands

Three-Component Photochemical 1,2,5-Trifunctionalizations of Alkenes toward Densely Functionalized Lynchpins

Radical remote 1,n-difunctionalization reactions (n > 2) of alkenes are powerful tools to efficiently introduce functional groups with selected distances into target molecules. Among these reactions, 1,5-difunctionalizations are an important subclass, leading to sought-after scaffolds, but typically suffer from tailored starting materials and strict limitations for the formed functional group in 2-position. Seeking to address these issues and to make radical 1,5-difunctionalizations of alkenes more applicable, we report a novel three-component 1,2,5-trifunctionalization reaction between imine-based bifunctional reagents and two distinct alkenes, driven by visible light energy transfer-catalysis. Key to achieving this selective one-step installation of three different functional groups via the choreographed formation of four bonds was the utilization of a 1,2-boron shift and the rigorous capitalization of radical polarities and stabilities. Thorough mechanistic studies were carried out, and the synthetic utility of the obtained products was demonstrated by various downstream modifications. Notably, in addition to the functionalization of individual functional groups, their interplay gave rise to a unique array of cyclic products.

Development and challenges in the discovery of 5-HT1A and 5-HT7 receptor ligands

Serotonin (5-hydroxytryptamine) is a small molecule that acts both in the central and peripheral nervous system as a neurotransmitter and a hormone, respectively. Serotonin is synthesized via a multi-stage pathway beginning with l-tryptophan, which is converted by an enzyme called tryptophan hydroxylase into L-5-Hydroxytryptophan. It is well-known for its significance in the control of mood, anxiety, depression, and insomnia as well as in normal human functions such as sleep, sexual activity, and appetite. Thus, for medical chemists and pharmaceutical firms, serotonin is one of the most desirable targets. Among the seven different classes of serotonin receptors, the 5-HT_1A was one of the first discovered serotonin receptors, and the 5-HT₇ was the last addition to the serotonin receptor family. Both the classes were thoroughly examined. 5-HT_1A neurotransmission-related dysfunctions are linked to many psychological conditions such as anxiety, depression, and movement disorders. 5-HT₇ is a member of the cell surface receptor GPCR superfamily and is regulated by the serotonin neurotransmitter. It has been the focus of intensive research efforts since its discovery, which was prompted by its presence in functionally important regions of the brain. The thalamus and hypothalamus have the highest 5-HT₇ receptor densities. They are also found in the hippocampus and cortex at higher densities. Thermoregulation, circadian rhythm, learning and memory, and sleep are all associated with the 5-HT₇ receptor. It is also suspected that this receptor may be involved in the control of mood, indicating that it may be a beneficial target for depression treatment. Several differently structured molecules such as aminotetralins, ergolines, arylpiperazines, indolylalkylamines, aporphines, and aryloxyalkyl-amines are known to bind to 5-HT_1A and 5-HT₇ receptor sites. In brain serotonin receptors 5-HT_1A and 5-HT₇ are strongly co-expressed in regions involved in depression. However, their functional interaction has not been identified. An overview of the 5-HT_1A and 5-HT₇ receptor ligands belonging to different chemical groups is mentioned in this review.

Multifunctional Arylsulfone and Arylsulfonamide-Based Ligands with Prominent Mood-Modulating Activity and Benign Safety Profile, Targeting Neuropsychiatric Symptoms of Dementia

The current pharmaceutical market lacks therapeutic agents designed to modulate behavioral disturbances associated with dementia. To address this unmet medical need, we designed multifunctional ligands characterized by a nanomolar affinity for clinically relevant targets that are associated with the disease pathology, namely, the 5-HT_2A/6/7 and D₂ receptors. Compounds that exhibited favorable functional efficacy, water solubility, and metabolic stability were selected for more detailed study. Pharmacological profiling revealed that compound 11 exerted pronounced antidepressant activity (MED 0.1 mg/kg), outperforming commonly available antidepressant drugs, while compound 16 elicited a robust anxiolytic activity (MED 1 mg/kg), exceeding comparator anxiolytics. In contrast to the existing psychotropic agents tested, the novel chemotypes did not negatively impact cognition. At a chronic dose regimen (25 days), 11 did not induce significant metabolic or adverse blood pressure disturbances. These promising therapeutic-like activities and benign safety profiles make the novel chemotypes potential treatment options for dementia patients.

N-Alkylated arylsulfonamides of (aryloxy)ethyl piperidines: 5-HT(7) receptor selectivity versus multireceptor profile

The N-alkylation of the sulfonamide moiety, in a group of arylsulfonamide derivatives of (aryloxy)ethyl piperidines, may be considered as a strategy for the design of selective 5-HT7 receptor ligands or multifunctional agents to extend a polypharmacological approach to the treatment of complex diseases. The study allowed for the identification of 31 (1-methyl-N-{1-[2-(2-(t-butyl)phenoxy)ethyl]piperidin-4-yl}-N-cyclopropylmethyl-1H-pyrazole-4-sulfonamide), a potent and selective 5-HT7 receptor antagonist and 33 (1-methyl-N-{1-[2-(biphenyl-2-yloxy)ethyl]piperidin-4-yl}-N-cyclopropylmethyl-1H-pyrazole-4-sulfonamide), as multimodal 5-HT/dopamine receptor ligand, as 5-HT2A/5-HT7/D2 receptor antagonists. Both selected compounds were evaluated in vivo in a forced swim test (FST) in mice and in a novel object recognition (NOR) task in rats, demonstrating distinct antidepressant-like and pro-cognitive properties (MED=1.25 mg/kg and 1 mg/kg, ip, respectively). These findings warrant further studies to explore the therapeutic potential of N-alkylated arylsulfonamides for the treatment of CNS disorders.

Arylsulfonamide derivatives of (aryloxy)ethylpiperidines as selective 5-HT7 receptor antagonists and their psychotropic properties

A novel series of potent 5-HT₇ receptor antagonist and their antidepressant, anxiolytic and pro-cognitive properties is described.

Serotonin 5-HT7 receptor agents: Structure-activity relationships and potential therapeutic applications in central nervous system disorders

Since its discovery in the 1940s in serum, the mammalian intestinal mucosa, and in the central nervous system, serotonin (5-HT) has been shown to be involved in virtually all cognitive and behavioral human functions, and alterations in its neurochemistry have been implicated in the etiology of a plethora of neuropsychiatric disorders. The cloning of 5-HT receptor subtypes has been of importance in enabling them to be classified as specific protein molecules encoded by specific genes. The 5-HT(7) receptor is the most recently classified member of the serotonin receptor family. Since its identification, it has been the subject of intense research efforts driven by its presence in functionally relevant regions of the brain. The availability of some selective antagonists and agonists, in combination with genetically modified mice lacking the 5-HT(7) receptor, has allowed for a better understanding of the pathophysiological role of this receptor. This paper reviews data on localization and pharmacological properties of the 5-HT(7) receptor, and summarizes the results of structure-activity relationship studies aimed at the discovery of selective 5-HT(7) receptor ligands. Additionally, an overview of the potential therapeutic applications of 5-HT(7) receptor agonists and antagonists in central nervous system disorders is presented.

5-HT(7) receptor modulators: a medicinal chemistry survey of recent patent literature (2004 - 2009)

IMPORTANCE OF THE FIELD

The 5-HT(7) receptors are discretely localized within the CNS (thalamus, hypothalamus, limbic and cortical regions). The 5-HT(7) receptors are also present in smooth muscle cells from blood vessels and have been reported in gastrointestinal tract as well as in rat lumbar dorsal root and sympathetic ganglia. The 5-HT(7) receptors have been implicated in depression, disorders related to circadian rhythms, pain and migraine. Thus, there is a great interest in developing potent and selective 5-HT(7) receptor modulators.

AREAS COVERED IN THIS REVIEW

This review article highlights the research advances published in the patent literature between January 2004 and December 2009, giving emphasis to the medicinal chemist's standpoint.

WHAT THE READER WILL GAIN

Readers will rapidly gain an overview of the various 5-HT(7) receptor modulators reported in the patent literature in the past 6 years. Furthermore, the readers will learn which structure type can interact with 5-HT(7) receptor and also the different companies that are the main players in the field.

TAKE HOME MESSAGE

Although no 5-HT(7) modulator has entered clinical trials, the development and future use of different agonists and antagonists suitable for use in vivo seem very promising.

Sulfonamides with the N-alkyl-N'-dialkylguanidine moiety as 5-HT7 receptor ligands

A series of arylsulfonamides containing guanidine incorporated in the structure of secondary amines (piperidine, piperazine) was synthesized on SynPhase Lanterns and evaluated for 5-HT(1A), 5-HT(2A), and 5-HT(7) receptors. The results demonstrated that N-alkyl-N'-dialkylguanidines displayed good 5-HT(7)/5-HT(1A) selectivity and may be regarded as promising structural core for development of 5-HT(7) ligands.

(Phenylpiperazinyl-butyl)oxindoles as selective 5-HT7 receptor antagonists

A series of potent 5-hydroxytryptamine 7 (5-HT 7) ligands has been synthesized that contain a 1,3-dihydro-2 H-indol-2-one (oxindole) skeleton. The binding of these compounds to the 5-HT 7 and 5-HT 1A receptors was measured. Despite the structural similarity of these two serotonin receptor subtypes, several derivatives exhibited a high selectivity to the 5-HT 7 receptor. According to the structure-activity relationship observations, compounds unsubstituted at the oxindole nitrogen atom and containing a tetramethylene spacer between the oxindole skeleton and the basic nitrogen atom are the most potent ligands. Concerning the basic group, besides the moieties of the 4-phenylpiperazine type, halophenyl-1,2,3,6-tetrahydropyridines also proved to be 5-HT 7 receptor-ligands. Because of halogen substitution on the aromatic rings, good metabolic stability could be achieved. A representative of the family, 3-{4-[4-(4-chlorophenyl)-piperazin-1-yl]-butyl}-3-ethyl-6-fluoro-1,3-dihydro-2 H-indol-2-one ( 9e') exhibited selective 5-HT 7 antagonist activity ( K i = 0.79 nM). The in vivo pharmacological potencies of these 5-HT 7 receptor-ligands were estimated by the conflict drinking (Vogel) and the light-dark anxiolytic tests.

Novel aminoethylbiphenyls as 5-HT7 receptor ligands

The synthesis of a series of aminoethylbiphenyls as novel 5-HT(7) receptor ligands is described. The novel derivatives exhibit high affinity for the 5-HT(7) receptor with selectivity toward 5-HT(1A) receptor.