Imidazo-thiazine, -diazinone and -diazepinone derivatives. Synthesis, structure and benzodiazepine receptor binding

Recent Developments in the Synthesis of Bicyclic Condensed Pyrimidinones

Abstract:

Functionalized bicyclic pyrimidinones and their derivatives are significant heterocyclic scaffolds being their all-around prevalence in biologically potent compounds. In several attempts to explore the different synthetic methodologies for the construction of bicyclic condensed pyrimidinones, different researchers from all across the globe have reported numerous substantial methods. In the present review, considerable work has been critically compiled on the synthesis of substituted and functionalized bicyclic pyrimidinones from 2000 onwards.

Synthesis of Novel Derivatives of (Benz)Imidazo[2,1-b]Pyrimido[4,5-d][1,3]Thiazine

Several derivatives of the novel heterocyclic systems 2-substituted-imidazo- and benzimidazo-[2,1- b]pyrimido[4,5- d][1,3]thiazine have been synthesised through the one-pot cyclocondensation of 2,4-dichloro-5-(chloromethyl)-6-methylpyrimidine with imidazolidine-2-thione and 1 H-benzimidazole-2(3 H)-thione and subsequently substituted by various secondary amines in moderately good yields.

Bicyclic imidazole-4-one derivatives: a new class of antagonists for the orphan G protein-coupled receptors GPR18 and GPR55

GPR18 and GPR55 are orphan G protein-coupled receptors (GPCRs) that interact with certain cannabinoid (CB) receptor ligands.

(S)-5-Benzyl- and 5-benzylidene-imidazo-4-one derivatives synthesized and studied for an understanding of their thermal reactivity

Static and flash vacuum pyrolysis were used to get insight into the mechanisms of decomposition of 3-(2-chloroethyl)imidazolidine-2,4-dione and 2,3-dihydroimidazo[2,1-b]thiazol-5(6H)-one derivatives.

The copper(i)-catalyzed tandem reaction of o-alkynylphenyl isothiocyanates with isocyanides: a rapid synthesis of 5H-benzo[d]imidazo[5,1-b][1,3]thiazines

An efficient route to 5H-benzo[d]imidazo[5,1-b][1,3]thiazines has been developed using the copper(i)-catalyzed tandem reaction of o-alkynylphenyl isothiocyanates with isocyanides in THF with Cs₂CO₃ as base.

Synthesis and activity of novel acylthiourea with hydantoin

The 41 novel acylthiourea derivatives with hydantoin were synthesized in moderate to excellent yields by using 5-(4-aminophenyl)- and 5-(4-aminobenzyl)- hydantoin or 5-(4-aminobenzyl)-thiohydantoin as raw materials and characterized by IR, ¹H NMR spectra and elementary analysis. The preliminary bioassay showed that these compounds exhibit certain selectively herbicidal activities with the 91%, 94% and 87% inhibition rates of 7l, 8o and 8p against B. campestris, 100%, 100% and 95% efficacy against B. campestris in a greenhouse test, respectively. 7a, 7b, 7c and 7d exhibited 74%, 79%, 79% and 71% inhibition rates against F. oxysporum, respectively.

Facile synthesis of 5-arylidene thiohydantoin by sequential sulfonylation/desulfination reaction

The sequential sulfonylation/desulfination reactions of 5-benzylthiohydantoin with excess arylsulfonyl chlorides in the presence of triethylamine have been developed to afford a wide range of 5-arylidene thiohydantoin derivatives in moderate to excellent yields. A plausible sulfonylation/desulfination mechanism was proposed. The bioassay showed that these compounds exhibit certain fungicidal activities with the 71.9% inhibition rate of 2K against B. cinerea, and 57.6% inhibition rate of 2m against A. solani, respectively.

Imidazo[2,1-b]thiazepines: synthesis, structure and evaluation of benzodiazepine receptor binding

As a continuation of our search for new ligands acting on benzodiazepine receptors among the fused 2-thiohydantoin derivatives, a series of 5-substituted imidazo[2,1-b]thiazepines was synthesized and investigated in radioligand binding studies at the benzodiazepine binding site of GABA(A) receptors in rat brain cortical membranes. Among ortho-substituted 5-arylidene-imidazo[2,1-b]thiazepines compounds could be identified which exhibit affinity for the benzodiazepine binding site at low micromolar concentrations. X-ray structure analyses for two compounds (6ae and 6ag) have been performed. In order to analyze the structure-activity relationships, 3D models of all compounds have been completed (using X-ray data). Physicochemical properties calculated (log P and log D) as well as experimental thin layer chromatography data were examined.

From thiourea to bicyclic structures: an original route to imidazo[2,1-b]thiazoles, 5H-thiazolo[3,2-a]pyrimidines, 7H-imidazo[2,1-b][1,3]thiazines, and 2H,6H-pyrimido[2,1-b][1,3]thiazines

We report an example of an efficient regioselective synthesis of biheterocyclic compounds using thiourea as starting material. In fact, N,N'-bis(dimethylaminomethylene)thiourea (1), easily prepared by double condensation of N,N-dimethylformamide dimethyl acetal with thiourea, can be reacted with haloketones or acrylic dienophiles to give thiazolic (2) and thiazinic (3) diazadienes, respectively, themselves undergoing cyclization reactions to yield imidazo[2,1-b]thiazoles, 5H-thiazolo[3,2-a]pyrimidines, 7H-imidazo[2,1-b][1,3]thiazines, and 2H,6H-pyrimido[2,1-b][1,3]thiazines without any regioisomeric ambiguity. This straightforward route represents an original and unambiguously regioselective pathway to these valuable heterocycles.

Antimycobacterial activity of 5-arylidene derivatives of hydantoin

The synthesis of various 5-arylidene-2-thiohydantoins and results of the primary assay in vitro for their antimycobacterial activity is reported. Eight of those compounds exhibited > 90% inhibition of Mycobacterium tuberculosis growth and for them the minimum inhibitory concentrations, cytotoxicity (IC50) and the selectivity index values were determined. The most active structure, (5Z)-5-(1,1'-biphenyl-4-ylmethylene)-2-thioxoimidazolidin-4-one, showed MIC = 0.78 microg/ml. For all compounds log P and log D (pH 6.5) values were calculated.