Search

In the course of aging, the steroidogenic function of the testes weakens and their gonadotropin sensitivity decreases. However, the underlying mechanisms are poorly understood. The goal of this work was to study the stimulating effects of human chorionic gonadotropin (hCG) and TP03, a low molecular weight agonist of luteinizing hormone (LH)/hCG receptor, on testosterone production and the expression of steroidogenic proteins in young (3-month-old) and aging (15-month-old) male rats and to investigate the activity of the adenylyl cyclase system in the membranes isolated from the rat testes. Treatment with hCG (100 IU/rat/day) and TP03 (15 mg/kg/day) was carried out for 3 days. In the testes of aging rats, adenylyl cyclase stimulation by gonadotropin and guanine nucleotide was decreased, indicating a weakening of the coupling of LH/hCG receptor and Gs protein, the main components of the adenylyl cyclase system regulating the steroidogenesis. In elderly rats, the blood testosterone levels and the expression of the Star, Cyp11a1, and Cyp17a1 genes, which encode the StAR protein and the steroidogenic enzymes cytochromes P450scc and P450-17α in the testes, were decreased. The stimulating effect of both hCG and TP03 on testosterone production diminished with age, although their effects on LH/hCG receptor are mediated by different mechanisms. In both young and aging rats, hCG treatment upregulated the expression of the genes encoding StAR, P450scc and dehydrogenase 3β-HSD; at the same time, Hsd17B expression in aging rats increased, and the expression of the genes encoding P450-17α and 17β-HSD decreased in young rats. In young rats, TP03 treatment upregulated Star and Cyp17a1 expression, and it increased Star and Hsd17B expression in aging rats. Thus, in the testes of aging rats, the coupling between the LH/hCG receptor and Gs protein and LH/hCG receptor sensitivity to agonists were weakened, which led to a decrease in hCG- and TP03-induced testosterone production and altered the basal and LH/hCG receptor agonist–stimulated expression levels of some steroidogenic protein genes.

For the preparation of compound libraries of Michael acceptors with tunable reactivity toward nuclophilic selenocysteine residue of thioredoxin reductase, a range of 3-arylglutaconic acids were required. The existing methods at the time had limited scope or involved several steps. A hitherto undescribed protocol for direct palladium(II) acetate-catalyzed arylation of glutaconic acid dimethyl ester at position 3 has been developed with a diverse set of arenediazonium tosylates followed by hydrolysis. This generally good-yielding two-step sequence displayed a propensity to deliver E-configured coupling products while compounds mostly featured in the literature were predominantly Z-configured. The possibility for preparing a library of 4-arylpyridine-2,6(1H,3H)-diones has been exemplified.

Attempted use of 3-arylglutaconic acids in the three-component version of the Castagnoli-Cushman reaction with amines and aromatic aldehydes resulted in an unexpected formation of 4,6-diaryl 1,6-dihydropyridine-2(3 H)-ones. These are of interest as representatives of a rare heterocyclic chemotype for de novo biological investigation. Alternatively, these compounds can be oxidized into their 2-pyridone counterparts, stereoselectively reduced to give cis-configured 4,6-diaryl 2-piperidones, or isomerized to 5,6-dihydropyridin-2(1 H)-ones. All the three scaffolds are well represented in the bioactive compound domain.

Human thioredoxin reductase 1 (TrxR1) is a selenocysteine-containing enzyme which plays a crucial role in regulating numerous redox signalling pathways within the cell. While its functioning is important in all cells, levels of TrxR1 expression are higher in cancer cells, possibly as an adaptation to much higher levels of reactive oxygen species and the need for more extensive DNA synthesis. This makes TrxR1 an attractive target for cancer therapy development. Inspired by the structure of disulphide compounds which have advanced through various stages of clinical development, we designed a series of dithiodiglycolic acid derivatives. These were prepared from respective thiol synthons using an iodine- or benzotriazolyl chloride-promoted oxidative disulphide bond formation. Inhibition of TrxR present in cell lysates from human neuroblastoma cells (SH-SY5Y) and rat liver cells indicated several compounds with a potential for TrxR inhibition. Some of these compounds were also tested for growth inhibition against two human cancer cell lines and normal human keratinocytes., Graphical Abstract

It was shown that the thienopyrimidine derivative TP03, a low-molecular-weight agonist of the luteinizing hormone receptor (LHR), during the treatment of male rats for 7 days steadily increased the production of testosterone (T), whose elevated level was retained for 7 days, and increased the expression of the gene for LHR, which indicates the maintenance of the sensitivity of Leydig cells to gonadotropins. At the same time, the steroidogenic effect of human chorionic gonadotropin (hCG), which significantly increased the T level on the first day of administration, was further weakened, which was accompanied by a decrease in the expression of the gene for LHR in the testes, indicating the development of resistance of Leydig cells to hCG. Along with this, in the case of hCG administration, a compensatory increase in the expression of genes of the steroidogenic enzymes, such as cytochrome P450scc and dehydrogenase 3β-HSD, was shown in the testes, while in the case of TP03 administration this effect was absent.

A novel chemotype topologically similar to known influenza virus PA endonuclease inhibitors has been designed. It was aimed to reproduce the extended topology of the known metal-chelating ligands with a p-phenylidene-linked bis-imidazoline scaffold. It was envisioned that aromatic groups introduced to this scaffolds via metal-catalyzed N-arylation (Buchwald-Hartwig or Chan-Evans-Lam) would contribute to lipophilic binding to the target and one of the imidazoline nitrogen atoms would ensure non-chelating coordination to the prosthetic divalent metal ion. The compounds displayed appreciable anti-influenza activity in vitro and substantial concentration window from the general cytotoxicity range. Docking analysis of low-energy poses of the most active compound (as well as their comparison to the binding of an inactive compound) revealed that these compounds reproduced similar binding components to a known PA endonuclease inhibitor and displayed similar binding pose and desired monodentate metal coordination, as was initially envisioned. These findings warrant further investigation of the mechanism of action of the newly discovered series.

The luteinizing hormone (LH) and human chorionic gonadotropin (hCG) stimulate the testosterone (T) production in Leydig cells via specifical binding to the LH/hCG receptor extracellular domain. The LH/hCG receptor can also be activated by low-molecular-weight (LMW) agonists that bind to the allosteric site located inside the transmembrane receptor channel. Since the allosteric sites in the LH/hCG and thyroid-stimulating hormone (TSH) receptors share a similar structure, LMW agonists of the LH/hCG receptor can affect activity of the TSH receptor and the synthesis of thyroid hormones which depend on this receptor. When designing selective activators of steroidogenesis, it is necessary to rule out this possibility. The aim of this study was to explore the effect of the seven previously synthesized thienopyrimidines (TPs), LMW agonists of the LH/hCG receptor, on the basal and hCG- and TSH-stimulated adenylyl cyclase (AC) activity in plasma membranes isolated from the rat testes and thyroid as well as on the basal and luliberin- and thyroliberin-stimulated levels of T and thyroid hormones following intraperitoneal (i.p.) TP administration to male rats. All seven TPs (10−4 M) increased the AC basal activity in rat testicular membranes, and in the case of combined action of TPs and hCG their stimulatory effects were additive. TPs did not affect the basal and TSH-stimulated AC activity in thyroid membranes. When administered to male rats, TPs (i.p., 25 mg/kg) increased the T level. The effect of TP03, a most active LH/hCG receptor LMW agonist, persisted under luliberin-induced activation of the gonadal axis. The nicotinamide moiety of TP21, in contrast to the structurally similar TP03, contains an additional methoxy group which alters receptor specificity of this compound. Thus, with the exception of TP21, all TPs sharing LH/hCG receptor agonistic activity, both under in vitro and in vivo conditions, do not affect the TSH receptor, indicative of their selectivity toward the gonadal axis.

Gold(I)-catalyzed hetero-tetradehydro-Diels-Alder cycloaddition of enynamides and cyanamides comprises an efficient route to diversely substituted 2,6-diaminopyridines (28 examples; yields up to 99%). The reaction proceeds under very mild conditions (DCM, rt) with high functional group tolerance. The obtained 2,6-diaminopyridines represent a useful synthetic platform with an easily modulated substitution pattern for subsequent functionalizations of both the pyridine core and the N-substituents.

A series of medicinally important dihydropyridin-2(1H)-ones have been prepared via a novel [4 + 2]-formal cycloaddition reaction of chalcone imines and homophthalic anhydrides, which is a rare example of lactam construction from an imine acting as a four-atom building block. In contrast to previous studies on the reactivity of homophthalic anhydrides towards similar substrates, N-tosyl chalcone imines, we found the possibility of switching chemoselectivity by changing substituents at the nitrogen atom, which leads to the formation of heterocycles instead of the expected carbocycles. This reaction is very similar in appearance to the classic 1,2-addition of cyclic anhydrides to imines, often referred to as the Castagnoli-Cushman reaction, but differs in mechanistic details (representing a 1,4-reaction of imine). The developed atom-economical, stereoselective and catalyst- and chromatography-free protocol provided facile access to 28 structurally diverse heterocyclic products (in up to 88% yield) including synthetically challenging annelated tricyclic and previously unreported pentaaryl-substituted dihydropyridin-2(1H)-ones.

Herein we report the synthesis of a set of seventeen 3-sulfonamide substituted coumarin derivatives. Prepared compounds were tested in vitro for inhibition of four physiologically relevant isoforms of the metalloenzyme human carbonic anhydrase (hCA, EC 4.2.1.1). Several coumarin sulfonamides displayed low nanomolar KI values against therapeutically relevant hCA II, IX, and XII, whereas they did not potently inhibit hCA I. Some of these compounds exerted a concentration-dependent antiproliferative action toward RT4 human bladder cancer and especially A431 human epidermoid carcinoma cell lines. In the meantime, the viability of non-tumorigenic hTERT immortalized human foreskin fibroblast cell line Bj-5ta was not significantly affected by the obtained derivatives. Interestingly, compound 10q (2-oxo-2H-benzo [h]chromene-3-sulfonamide) showed a profound and selective dose-dependent inhibition of A431 cell growth with low nanomolar IC50 values. We demonstrated that 10q possessed a concentration-dependent apoptosis induction activity associated with caspase 3/7 activation in cancer cells. As carbonic anhydrase isoforms in question were not potently inhibited by this compound, its antiproliferative effects likely involve other mechanisms, such as DNA intercalation. Compound 10q clearly represents a viable lead for further development of new-generation anticancer agents.

Diversity-oriented synthesis (DOS) is a rich source for novel lead structures in Medicinal Chemistry. In this study, we present a DOS-compatible method for synthesis of compounds bearing a free thiol moiety. The procedure relies on Rh(II)-catalyzed coupling of dithiols to diazo building blocks. The synthetized library was probed against metallo-β-lactamases (MBLs) NDM-1 and VIM-1. Biochemical and biological evaluation led to identification of novel potent MBL inhibitors with antibiotic adjuvant activity.

Diazocarbonyl compounds have found numerous applications in many areas of chemistry. Among the most developed fields of diazo chemistry is the preparation of azoles from diazo compounds. This approach represents a useful alternative to more conventional methods of the synthesis of azoles. A comprehensive review on the preparation of various azoles (oxazoles, thiazoles, imidazoles, pyrazoles, triazoles, and tetrazoles) from diazocarbonyl and related compounds is presented for the first time along with discussion of advantages and disadvantages of «diazo» approaches to azoles.

α-Diazo homophotalimides were reacted with various propiolic acids on Rh

Spirocyclic scaffolds are incorporated in various approved drugs and drug candidates. The increasing interest in less planar bioactive compounds has given rise to the development of synthetic methodologies for the preparation of spirocyclic scaffolds. In this Perspective, we summarize the diverse synthetic routes to obtain spirocyclic systems. The impact of spirocycles on potency and selectivity, including the aspect of stereochemistry, is discussed. Furthermore, we examine the changes in physicochemical properties as well as in in vitro and in vivo ADME using selected studies that compare spirocyclic compounds to their nonspirocyclic counterparts. In conclusion, the value of spirocyclic scaffolds in medicinal chemistry is discussed.

A novel 3,4-dihydroisoquinol-1-one-4-carboxamide scaffold was designed as the basis for the development of novel inhibitors of poly(ADP-ribose) polymerase (PARP). Synthesis of 3,4-dihydroisoquinol-1-one-4-carboxylic acids was achieved using the previously developed protocol based on the modified Castagnoli-Cushman reaction of homophthalic anhydrides and 1,3,5-triazinanes as formaldimine synthetic equivalents. Employment of 2,4-dimethoxy groups on the nitrogen atom of the latter allowed preparation of 2,3-unsubatituted 3,4-dihydroquinolone core building blocks. Iterative synthesis and in vitro biological testing of the amides resulting from the amidation of these carboxylic acids allowed not only drawing important structure-activity generalisations (corroborated by in silico docking simulation) but also the identification of the lead compound, 4-([1,4'-bipiperidine]-1'-carbonyl)-7-fluoro-3,4-dihydroisoquinolin-1(2H)-one, as the candidate for further preclinical development. The lead compound as well as its des-fluoro analog were compared to the approved PARP1 inhibitor, anticancer drug Olaparib, in terms of their molecular characteristics defining druglikeness as well as experimentally determined ADME parameters. The newly developed series demonstrated clear advantages over Olaparib in terms of molecular weight, hydrophilicity, human liver microsomal and plasma stability as well as plasma protein binding. Further preclinical investigation of the lead compound is highly warranted.

We report on gold(I)-catalyzed oxidative annulation involving ynamides, nitriles, and 2,3-dichloropyridine N-oxide. The application of 2,3-dichloropyridine N-oxide as an oxygen atom transfer reagent reverses the regioselectivity to give 5-amino-1,3-oxazoles, in comparison with the previously reported syntheses of aminooxazoles based on gold-catalyzed nitrene transfers to ynamides to furnish 4-amino-1,3-oxazoles. The developed oxygen atom transfer approach allows the generation of 1,3-oxazoles containing a variety of sulfonyl-protected alkylamino groups in the fifth position of the oxazole ring (29 examples; up to 88% yields). In addition, the use of N-substituted nitriles, namely cyanamides, leads to the facile generation of difficult-to-obtain 2,5-diaminooxazoles. The process is feasible for wide ranges of ynamides or nitriles, and it can be conducted in gram scale.

Currently, available glioblastoma (GBM) treatment remains ineffective, with relapse after initial response and low survival rate of GBM patients. The reasons behind limited capacities for GBM treatment are high tumor heterogeneity, invasiveness, and occurrence of drug resistance. Therefore, developing novel therapeutic strategies is of utmost importance. Thioredoxin reductase (TrxR) is a novel, promising target due to its overexpression in many cancer types and important role in cancer progression. Previous research on Ugi-type Michael acceptors-inhibitors of TrxR showed desirable anticancer properties, with significant selectivity toward cancer cells. Herein, two TrxR inhibitors, 5 and 6, underwent in-depth study on multidrug-resistant (MDR) glioma cell lines. Besides the antioxidative effects, 5 and 6 induced cell death, decreased cell proliferation, and suppressed invasion and migration of glioma cells. Both compounds showed a synergistic effect in combination with temozolomide (TMZ), a first-line chemotherapeutic for GBM treatment. Moreover, 5 and 6 affected activity of P-glycoprotein extrusion pump that could be found in cancer cells and in the blood-brain barrier (BBB), thus showing potential for suppressing MDR phenotype in cancer cells and evading BBB. In conclusion, investigated TrxR inhibitors are effective anticancer compounds, acting through inhibition of the thioredoxin system and perturbation of antioxidative defense systems of glioma cells. They are suitable for combining with other chemotherapeutics, able to surpass the BBB and overcome MDR. Thus, our findings suggest further exploration of Ugi-type Michael acceptors-TrxR inhibitors' potential as an adjuvant therapy for GBM treatment.

Low-molecular-weight agonists of luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptor (LHCGR), which interact with LHCGR transmembrane allosteric site and, in comparison with gonadotropins, more selectively activate intracellular effectors, are currently being developed. Meanwhile, their effects on testicular steroidogenesis have not been studied. The purpose of this work is to perform a comparative study of the effects of 5-amino-N-tert-butyl-4-(3-(1-methylpyrazole-4-carboxamido)phenyl)-2-(methylthio)thieno[2,3-d] pyrimidine-6-carboxamide (TP4/2), a LHCGR allosteric agonist developed by us, and hCG on adenylyl cyclase activity in rat testicular membranes, testosterone levels, testicular steroidogenesis and spermatogenesis in young (four-month-old), aging (18-month-old) and diabetic male Wistar rats. Type 1 diabetes was caused by a single streptozotocin (50 mg/kg) injection. TP4/2 (20 mg/kg/day) and hCG (20 IU/rat/day) were administered for 5 days. TP4/2 was less effective in adenylyl cyclase stimulation and ability to activate steroidogenesis when administered once into rats. On the 3rd&ndash, 5th day, TP4/2 and hCG steroidogenic effects in young adult, aging and diabetic rats were comparable. Unlike hCG, TP4/2 did not inhibit LHCGR gene expression and did not hyperstimulate the testicular steroidogenesis system, moderately increasing steroidogenic proteins gene expression and testosterone production. In aging and diabetic testes, TP4/2 improved spermatogenesis. Thus, during five-day administration, TP4/2 steadily stimulates testicular steroidogenesis, and can be used to prevent androgen deficiency in aging and diabetes.

A wide range of α-diazo-β-ketosulfones have been applied to thermally promoted tandem Wolff rearrangement – Staudinger [2+2] cycloaddition with imines to give polysubstituted β-lactam sulfones. Dia­stereomerically pure syn-diastereomers were obtained in good yields and the relative stereochemistry was confirmed by single-crystal X-ray crystallography. These findings significantly expand the scope of this transformation, in contrast to substantial limitations reported previously. Moreover, this methodology enables flexible exploration of new substitution patterns around the privileged β-lactam core for drug design and optimization.

The earlier reported three-component Castagnoli-Cushman-type synthesis of 1,4,6-trisubstituted 1,6-dihydropyridin-2-(3

Indole-fused cyclic anhydrides earlier deemed unreactive in the Castagnoli-Cushman reaction with imines have been rendered valid participant in this process. The new reaction format involves the use of respective indole-based dicarboxylic acids and in situ cyclodehydration of the latter by acetic anhydride. This finding validates a fundamentally new approach to synthesizing compounds based on the privileged 1,2,3,4-tetrahydropyrazino[1,2-a]indole core characterized by hitherto undescribed substitution pattern.

2,3-Dichloropyridine N-oxide, a novel oxygen transfer reagent, allows the conductance of the gold(I)-catalyzed oxidation of alkynes to 1,2-dicarbonyls in the absence of any acid additives and under mild conditions to furnish the target species, including those derivatized by highly acid-sensitive groups. The developed strategy is effective for a wide range of alkyne substrates such as terminal- and internal alkynes, ynamides, alkynyl ethers/thioethers, and even unsubstituted acetylene (40 examples; yields up to 99%). The oxidation was successfully integrated into the trapping of reactive dicarbonyls by one-pot heterocyclization and into the synthesis of six-membered azaheterocycles. This synthetic acid-free route was also successfully applied for the total synthesis of a natural 1,2-diketone.

A method to convert tertiary N-propargylamides into 1,2,4-trisubstituted imidazoles using ammonium chloride and zinc triflate as the catalyst is reported. The method is convenient, practical and employs conventional heating. It is also applicable to N-propargyl lactams and tends to populate the so-called ‘lead-like’ chemistry space.

The first example of the Castagnoli-Cushman reaction of homophthalic acid with an amine and an aldehyde conducted in a three-component format is reported. This new protocol employs no dehydrating agents and, unlike the traditional Castagnoli-Cushman reaction of homophthalic anhydride, allows simultaneous mixing of all three reagents and provides good to excellent yields of trans-configured tetrahydroisoquinolonic acids.

Five lactam chemotypes amenable by the Castagnoli-Cushman reaction of imines and cyclic anhydrides have been investigated for their ability to activate p53 tumor suppressing transcription factor thus induce apoptosis in p53+ cancer cells. A virtual library of 1.07 million chemically diverse compounds based on these scaffolds was subjected to in silico screening first. The compounds displaying high docking score were visually prioritized to identify the best-fitting compounds, i. e. the ones which adequately mimic the interactions of clinical candidate inhibitor Nutlin-3a. These 38 compounds were synthesized and tested for apoptosis induction in p53+ H116 cancer cells to identify 9 potent apoptosis-inducers (two of them exceeding the activity of Nutlin-3a) which belonged to four different chemotypes. The activation of p53 involved in the proapoptotic activity observed was supported by effective induction of EGFP expression in human osteocarcinoma U2OS-pLV reporter cell line. Moreover, the two most potent apoptosis inducers displayed antiproliferative profile identical to several known advanced p53 activators: they inhibited the growth of p53+/+ HCT116 cells in much lower concentration range compared to p53-/- HCT116 cells.

Pyrazole-fused cyclic anhydrides have been employed for the first time as the Castagnoli–Cushman reaction partners to produce hitherto unknown 4-oxo-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine-7-carboxylates in remarkably convenient and speedy fashion. Attempts to realize the same chemistry with indole and benzimidazole analogues failed.

Hitherto undescribed 3-unsubstituted tetrahydroisoquinolonic acids (isolated as their respective methyl esters) were accessed for the first time by the uncatalyzed, thermally promoted Castagnoli–Cushman reaction (CCR) of homophthalic anhydride (HPA) and a series of 1,3,5-triazinanes. The moderate yields observed in some cases are most likely associated with a persistent impurity also formed in these reactions. The new scaffold is expected to find novel medicinal utility (compared to the traditional CCR adducts) because it lacks a substituent at the 3-position.

The first example of employing a mixed carboxylic-sulfonic anhydride in reaction with imines is reported. Unlike its well-studied isostere homophthalic anhydride, benzo[c][1,2]oxathiin-3(4H)-one 1,1-dioxide gave no product of a formal [4 + 2] cycloaddition and only followed an alternative reaction pathway toward β-lactams, presumably, via a formal [2 + 2] cycloaddition (a Staudinger-type reaction). Optimized reaction conditions involve the use of triethylamine as a base promoter, which also allows isolating the product β-lactam benzene sulfonic acids as respective triethylammonium salts by conventional column chromatography. The reaction shows some preference to trans-isomer formation; pure diastereomers can be isolated in some cases.

The first example of the Buchner-Curtius-Schlotterbeck reaction of cyclic ketones with a stabilized cyclic diazo compound partner is described. The approach towards spirocyclic scaffolds has been exemplified with readily available ∝-diazo-γ-butyrolactone. The reaction proved to be viable with BF3∙OEt2 as the preferred catalyst and displayed substantial sensitivity to the size of the cyclic ketone.

The versatile conversion of propargylic amides to the respective 2-substituted 5-methyloxazoles was efficiently catalyzed by Zn(OTf)2 (5 mol%) under microwave irradiation in toluene. The method was applicable to a wide range of aliphatic, aromatic and heteroaromatic propargylic amides and thus represents a useful method which is complementary to the existing metal-catalyzed protocols, considering the ready availability of Zn(OTf)2.

Scaffold-generating transformations of the Groebke-Blackburn-Bienayme (GBB) reaction products are reviewed. The literature cases were grouped according to the reactions employed as the post-condensational event as follows: lactamization, intramolecular arylation, intramolecular Michael addition, cyclizations involving an alkyne moiety and miscellaneous. Although synthetic strategic based on the post-GBB modifications have been exploited to a lesser extent compared to post-Ugi modifications, the interest of researchers to the GBB reaction as the platform for designing new polycyclic scaffolds has been on the rise in the past decade.

An unusual reactivity of Rh(II) carbenes generated from (E)-3-(2-pyridylmethylene)-4-diazopyrrolidine-2,5-diones was discovered which led to a novel type of fluorescent annelated indolizines (X-ray confirmed structure). The reaction was found to be insensitive to substitution pattern at pyrrolidine nitrogen atom and delivered a series of nine novel indolizines in 74–94% yields. Photophysical properties of obtained indolizines were investigated, which proved them to be blue or green luminophores with absolute quantum yields up to 13.8%. The latter strongly depended on substitution pattern at pyrrolidine nitrogen atom.

This review summarizes recent developments in multicomponent reactions of diazo compounds. The role of diazo reagent and the type of interaction between components was analyzed to structure the discussion. In contrast to previous reviews on related topics mostly focused on metal catalyzed transformations, a substantial amount of organocatalytic or catalyst-free methodologies is covered in this work.

A short and practically convenient, modular approach to hitherto unknown dehydromorpholine sulfones and sulfonamides from α-acyl-α-diazomethyl sulfones and sulfonamides, respectively, has been developed. It involves Rh(II) carbene insertion into the O H bond of 2-bromoethanol followed by thermally promoted tandem SN2 displacement of the bromine atom by a primary amine and cyclodehydration.

Herein we report the synthesis of a set of thirty-four primary sulfonamides generated via formal N–H-insertion of metal carbenes into anilinic amino group of sulfanilamide and its meta-substituted analog. Obtained compounds were tested in vitro as inhibitors of four physiologically significant isoforms of the metalloenzyme human carbonic anhydrase (hCA, EC 4.2.1.1). Many of the synthesized sulfonamides displayed low nanomolar Ki values against therapeutically relevant hCA II, IX, and XII, whereas they did not potently inhibit hCA I. Provided the promising activity profiles of the substances towards tumor-associated hCA IX and XII isozymes, single-concentration MTT test was performed for the entire set. Disappointingly, most of the discovered hCA inhibitors did not significantly suppress the growth of cancer cells either in normoxia or CoCl2 induced hypoxic conditions. The only two compounds exerting profound antiproliferative effect turned out to be modest hCA inhibitors. Their out of the range activity in cells is likely attributive to the presence of Michael acceptor substructure which can potentially act either through the inhibition of Thioredoxin reductases (TrxRs, EC 1.8.1.9) or nonspecific covalent binding to cell proteins.

Luteinizing hormone (LH) and its homologue, human chorionic gonadotropin (hCG), are very important regulators of the reproductive system. These hormones stimulate various types of G proteins—primarily, Gs and Gq proteins—by binding to the specific LH-hCG receptor, which leads to the activation of adenylate cyclase (AC) and phospholipase C, respectively. It has been suggested that many side effects of LH and hCG are associated with low selectivity of their effect on G proteins. Low-molecular agonists of LH-hCG receptor developed on the basis of thienopyrimidine derivatives do not cause these side effects, and differences in the interaction with G proteins may be ones of the cause for this. To test this, a comparative study of the effect of hCG and synthesized by us thienopyrimidine derivative, 5-amino-N-tert-butyl-2-(methylsulfanyl)-4-(3-(nicotinamido)phenyl)thieno[2,3-d]pyrimidine-6-carboxamide (TP03) on the AC activity and GTP binding of G proteins in plasma membranes isolated from the rat ovaries and testes was performed. Cholera toxin (CT) and pertussis toxin (PT) were used to selectively switch off the signal transduction via Gs and Gi/o proteins, the peptide corresponding to the C-terminal segment 349–359 of the Gαq subunit was used to suppress Gq-dependent cascades. It was shown that treatment of ovarian and testicular membranes with CT resulted in suppression of TP03 and hCG stimulatory effects on the AC activity, but in different ways influenced the GTP binding stimulation: it completely blocked the effect of 10–6 M TP03 and reduced by 45–46% the effect of hCG (10–8 M). Preincubation of membranes with the peptide 349–359 reduced the hCG stimulatory effect on GTP binding by 34 (ovaries) and 45% (testes), but did not affect the corresponding effect of 10–6 M TP03. Preincubation with the peptide 349–359 also reduced the GTP stimulatory effect of 10–4 M TP03, but to a small extent. The obtained data indicate that, in contrast to hCG, the targets of which in the ovaries and testes are Gs and Gq proteins, the action of TP03 is realized mainly via Gs proteins. Only at a concentration that exceeds EC50 by two orders TP03 is capable to relatively weakly activate Gq proteins. The PT treatment of the membranes did not affect the effects of TP03 and hCG, which indicates the lack of their effective interaction with Gi/o proteins. Thus, the selectivity of activation of Gs-dependent cascades responsible for the synthesis and production of steroid hormones is a significant advantage of low-molecular agonists of LH-hCG receptor over gonadotropins.

A new format for the Castagnoli–Cushman reaction of structurally diverse dicarboxylic acids, amines, and aldehydes in the presence of acetic anhydride as dehydrating agent is described. The reaction is distinctly amenable to parallel format: the combinatorial array of 180 reactions delivered 157 products of >85% purity without chromatographic purification (of this number, 143 compounds had >94% purity). The new method offers a convenient preparation of the skeletally and peripherally diverse, lead- and druglike γ- and δ-lactam carboxylic acids with high diastereoselectivity in combinatorial fashion.

Attempted reaction of indolenines (which represent rather sterically hindered cyclic imines) with a series of dicarboxylic acid anhydrides yielded no expected product, the Castagnoli-Cushman lactam. Instead, products presumably formed via N-acyliminium species trapping by a carboxylate anion. Among them, hydrolytically labile 2:2 adducts of an indolenine and a cyclic anhydride, containing a 16-membered cyclic core, are particularly intriguing. This result contradicts the recently reported successful Castagnoli-Cushman reaction of indolenines with homophthalic anhydride suggesting a mechanistic switch in the course of the reaction.

Literature examples illustrating the use of oxalyl chloride to prepare dicarboxylic acid anhydrides are surprisingly limited. At the same time, we have discovered a method involving the use of this readily available reagent which allowed the preparation of novel cyclic anhydrides where other, more conventional, methods had failed. Herein, we demonstrate that the method is applicable to a wide diversity of substrates, delivers good to excellent yields of cyclic anhydrides without chromatographic purification and can be considered a synthetic tool of choice whenever dicarboxylic acid cyclodehydration is required.

A series of 15 benzene-fused hexahydropyrrolo[1,2-b]isoquinolonic acids with substantial degree of steric encumbrance has been prepared via a novel variant of the Castagnoli–Cushman reaction of homophthalic anhydride (HPA) and various indolenines. The employment of a special kind of a cyclic imine component reaction allowed, for the first time, isolating a Mannich-type adduct between HPA and an imine component which has been postulated but never obtained in similar reactions.

Castagnoli–Cushman reaction of imines derived from 2-chloropyridine-3-carboxaldehyde with a cyclic anhydride (4-(methylsulfonyl)-morpholine-2,6-dione) conducted at 110°C in DMF over 1 h, as expected, led to a mixture of trans- and cis-configured carboxylic acids. However, the latter underwent a spontaneous intramolecular reaction of the carboxylic functionality onto the labile nearby 2-chloropyridine moiety to give the respective tricyclic lactones in 17–23% yield, along with 41–68% yield of the uncyclized trans-configured products (isolated as methyl esters).