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Using DABSO as a substrate, different simple to complex structures can be constructed, such as sulfonyl fluorides, sulfonamides, sulfonohydrazides, sulfonic esters, and sulfones. In this review, we investigate the role of DABSO in organic synthesis.

An efficient strategy for the synthesis of functionalized 1-aminoisoquinoline derivatives has been developed through the reaction of o-alkynylbenzaldoximes with 2H-azirines using electrophiles.

A diastereoselective cascade annulation between allenoates and

We describe a novel and efficient synthetic strategy to construct the linear homoallylic quinolone structures through the intermolecular addition of 2-alkynylquinoline toiN/i-allenyl sulfonamides. We developed the regio- and diastereoselective transition metal-free hydroalkylation of 1,2-dienes by a structure containing a push-pull system. Moreover, the present work was carried out with a high atom economy, mild reaction conditions, and moderate to high yields.

In this project, a moderately efficient approach to multisubstituted N-(isoquinolin-1-yl)sulfonamide derivatives was illustrated, utilizing ortho-alkynylbenzaldoximes and zwitterionic ketenimine salts in a tandem reaction catalyzed by silver oxide. The oxophilicity of Ag2O, along with its nature as Lewis acid, pave the way for a smooth [3 + 2] cycloaddition between isoquinoline N-oxides and ketenimine species, which is a key step in this reaction. DFT calculation suggests that 1,3-dipolar cycloaddition of nitrone and ketenimine proceeds through a selective stepwise mechanism.

A novel copper-catalyzed cycloisomerization of unactivated allene-tethered O-propargyl oximes has been developed for the synthesis of hexahydropyrrolo[3,4-b]azepin-5(4H)-ones. This one-pot domino reaction proceeds via a [2,3]-sigmatropic rearrangement, a [3 + 2] cycloaddition, and another [3,3]-sigmatropic rearrangement. The methodology offers a practical and straightforward route for the rapid assembly of both ring components of the fused bicyclic motifs from acyclic precursors by simultaneously forming four new bonds (a C═O, a C═N, and two C-C bonds) in a single step.

β-secretase 1 (BACE1) plays a pivotal role in the pathology of Alzheimer׳s disease via accumulation beta amyloid in the brain. In this context, identifying new scaffolds that block BACE1 is of great importance despite all pharmacokinetic drawbacks that peptide-like structures have. Here, we report a new core structure based on novel unusual amino acids by substituting phenyl amide group in the P1 position and small alkyl groups in the P1′ site that results in the formation of new biological active peptides in micromolar level. Three different scaffolds were designed based on docking studies to efficiently interact with critical Asp32 residue in the active site of BACE1 and incorporated in peptides synthesis by Fmoc solid-phase peptide synthesis (SPPS) methodology to achieve desired compounds in good yield. The inhibitory activity of all synthesized peptides was examined by FRET-based enzymatic assay. The peptide 7 showed the best inhibitory activity with IC50 = 98.14 µM. Results of this investigation revealed that utilizing unusual amino acids as building blocks for the synthesis of peptidomimetics would be an option for the development and optimization of pharmaceutical structures. The inhibition of β-secretase 1 (BACE1) is potentially important approach to treatment of Alzheimer disease (AD). Novel series of peptides coupled to the new unusual amino acids scaffold were investigated as BACE1 inhibitors in this study. The design of these peptides was mostly affected by OM00-3. Based on observations, in good agreement between BACE-1 inhibition assessment and docking methodology, peptide 7 was the most potent compound between all and could be the basis of future studies.

A tandem reaction of 2-alkynylbenzaldoximes with propargylic alcohols has been developed for the synthesis of α-(4-bromo-isoquinolin-1-yl)-propenones. Employing 2-alkynylbenzaldoximes as a precursor in the presence of Br

The silver(I)-catalyzed reaction of ortho-alkynylbenzaldoximes with propargylic alcohols represents a new strategy for the divergent one-pot synthesis of 2-(isoquinolin-1-yl) prop-2-en-1-ones via tandem 6-endo-cyclization, 1,3-dipolar cycloaddition, and intramolecular dehydrative opening of the 2,3-dihydroisoxazole ring. This synthetic protocol tolerates a wide variety of ortho-alkynylbenzaldoximes and propargylic alcohols and affords the corresponding products in excellent yields.

Bis(imidazolium) chlorides based on 1,2-phenylenediamine were introduced as efficient ligand precursors in the Pd-catalyzed Mizoroki-Heck cross-coupling reactions of substituted aryl halides with activated alkenes to afford the corresponding functionalized alkenes. While high to excellent yields (78–96%) were obtained with aryl bromides, moderate yields (51–59%) were achieved for aryl chlorides in this protocol.

Arg-Gly-Asp (RGD) peptides represent the most outstanding recognition motif involved in cell adhesion that binds to the αv β3 integrin, which has been targeted for cancer therapy. Various RGD-containing peptides and peptidomimetics have been designed and synthesized to selectively inhibit this integrin. In this study, the synthesis of RGD-based peptides through the incorporation of the short bioactive peptide Phe-Ala-Lys-Leu-Phe (FAKLF) at the C and N termini of RGD has been achieved by using a solid-phase peptide synthesis approach. The peptides were purified by means of preparative RP-HPLC and their structures were confirmed through HRMS (ESI). The MTT assay revealed that the RGD and FAKLF peptides inhibited the proliferation of human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner, with IC50 values of 3000 and 500 ng mL-1 , respectively. Interestingly, a drastic improvement was observed in the antiproliferative activity of the combined structures of the FAKLFRGD and RGDFAKLF peptides, leading to IC50 values of 200 and 136.7 ng mL-1 , respectively. Meanwhile, based on apoptosis results, the potential of peptides to induce apoptosis, in accordance with their antiproliferative activity, indicated that the RGD and FAKLF peptides, and the peptides synthesized based on their combinations induced cell apoptosis in a dose-dependent manner followed by inhibition of the proliferation of endothelial cells. Moreover, the incorporation of d-leucine increased the induction of apoptosis by these peptides.

A highly efficient and stable novel class of allenic-Ugi products through a Crabbé homologation reaction is successfully demonstrated. Then, a regio- and chemo-selective cyclization of allenic-Ugi derivatives in a 5-exo-dig fashion to access 3-pyrroline skeletons is developed. Also, computational studies were performed and explained to provide insights into the reaction mechanism. This approach displays high bond-forming efficiency and atom economy with high yields.

Curcumin is a natural product with multiple biological activities and numerous potential therapeutic applications. In present study, the influence of curcumin and its degradation products (DPs) on the amyloid aggregation of Tau protein and the related PHF6 peptide were investigated. We provided experimental/theoretical evidence for suppressing effects of the compounds on the amyloid formation using far-UV CD as well as AFM, XRD and docking techniques and showed that the parent curcumin displayed stronger inhibition effect against Tau fibril aggregation. The obtained results suggest that the curcumin/DPs binding sites on the Tau molecule are likely to be the same, and provide a good structural basis to explain the efficient aggregation suppressing behavior of the curcumin, compared to the DPs. So, developing more stable curcumin nanoparticle formulations with improved curcumin bioavailability are of great importance. Curcumin's multi-functionality is also highly significant for the therapeutic application of this natural compound against various human diseases.

A novel and efficient metal-free C–H functionalization of enynals is developed to synthesize α-pyrone derivatives via the formation of two C–O bonds. In this project, K2S2O8 has been introduced as an efficient oxygen source and C–H functionalization agent in regioselective oxidative cyclization reaction with a relatively broad substrate scope.

A novel metal-free direct addition of molecular oxygen to the C-C triple bond toward benzannulated oxygen-bridged seven-membered ring systems and aza[3.1.0]bicycle skeletons under 3O2 atmosphere has been described. The reaction proceeds through at least three intramolecular C-O and C-C bond forming steps via green, simple, and unprecedented domino radical processes with high selectivity and good yields.

An efficient metal-free approach for the synthesis of N-coumaryl amino acids and the first one-step synthesis of 4-hydrazinocoumarin from 4-hydroxycoumarin was developed. The nucleophilic addition of amino acid methyl esters to 4-tosylcoumarins produced a series of 4-N-α-coumaryl amino acids in good to excellent yields without racemization. The antioxidant activities of the synthesized compounds were investigated using DPPH and FRAP methods. 4-Hydrazinocoumarin and N-coumaryl tyrosine had the best antioxidant activity. The antimicrobial activities of the compounds against Gram-positive was stronger than Gram-negative. 4-Hydrazinocoumarin showed the best antibacterial effect.

Background: Somatic ACE is a two-domain protein, C and N which are resulted from gene duplication. Presence of two active sites with particular properties, demonstrates functional significance of each domain. Increased levels of circulating N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), could be the result of ACE N-domain selective inhibition. Moreover, ACE C-domain specific inhibitors are able to inactivate bradykinin and inhibit the conversion of angiotensin I to angiotensin II in order to regulate blood pressure as well as reduced side effect profiles. Methods: The present study was designed to determine ACE domain specificity of the novel ACE inhibitor, onopordia which was recently isolated from Onopordon acanthium L. The ACE inhibition activity was determined using Abz-SDK (Dnp)P-OH and Abz-LFK(Dnp)-OH as ACE domain selective substrates. IC50 values of onopordia determined and compared with those of captopril as the standard. Results: IC50 values of onopordia for ACE N and C- domains were 180 µM and 244 µM respectively which demonstrated approximately similar affinity of the mentioned compound to ACE C and N-domains. A pharmacophore model was further generated based on onopordia interactions with the relevant ACE domain active sites. Conclusion: According to onopordia interactions in the ACE C and N-domain active sits, it is a potential to generate more potent and also specific inhibitor based on this new scaffold by doing accurate adjustments. Therefore, this study provides the molecular basis for further designing ACE inhibitors, which are new therapeutics in combating tissue fibrosis diseases.

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 efficient approach for the synthesis of pyranoquinolines through the indium-catalyzed activation of alkynes is reported. Intramolecular hydroamidation of alkynes can proceed through alkyne activation by indium(III) and then 6-exo-dig cyclization, leading to a fused pyran ring with high selectivity, high atom economy, and good to excellent yields. The cyclization was accomplished through the oxygen, not the nitrogen, of the amide functional group.

Context: Curcumin, a naturally occurring polyphenol, has been extensively studied for its broad-spectrum anticancer effects. The potential benefits are, however, limited due to its poor water solubility and rapid degradation which result in low bioavailability on administration. Objectives: This study encapsulates curcumin in nanoliposomes including an integrin-homing peptide combined with a C end R neuropilin-1 targeting motif for targeted delivery and receptor-mediated internalization, respectively. Materials and methods: The linear GHHNGR (Glycine–Histidine–Histidine–Asparagine–Glycine–Arginine) was synthesized through F-moc chemistry on 2-chlorotrityl chloride resin and conjugated to oleic acid. The lipoyl-peptide units were then co-assembled with lecithin and 0–75 mole % Tween-80 into liposomes. Curcumin was passively entrapped using a film hydration technique and its degradation profile was examined within seven consecutive days. The cytotoxic effects of the curcumin-loaded liposomes were studied on MCF-7 and MDA-MB-468, during 24 h exposure in MTT assay. Results: The maximum curcumin entrapment (15.5% W/W) and minimum degradation (

A diversity-oriented access to isoxazolino and isoxazolo benzazepines is elaborated via a post-Ugi heteroannulation involving intramolecular 1,3-dipolar cycloaddition reaction of nitrile oxides with alkenes and alkynes. This sequence offers an interesting multicomponent entry to a library of isoxazolino and isoxazolo benzazepines under mild reaction conditions in good to excellent yields.

The synthesis of modified RGD peptides and their conjugation to the pyrazine skeleton at their N-terminus are described. To modify and alter the RGD sequence, short bioactive peptides such as FALKF and NGRG were added to the RGD N-terminus. Moreover, the in vitro investigation of these modified peptides, by a cell adhesion assay using the melanoma cell lines M21 expressing alpha(v)beta(3) and M21L lacking alpha(v) expression, was made and interestingly peptide 4 containing the pyrazine moiety with the linear RGDFAKLF sequence gave the best IC50 value with M21 and all the peptides were unable to bind to M21L, demonstrating the selective recognition to alpha(v)beta(3). The results showed pyrazine plays an essential role in the activity of the peptides. From these results, we can suggest that these peptides can affect cancer cells by abrogation of cell adhesion (cell migration).

A stereoselective catalyst-free one-pot pseudo six-component reaction of isatoic anhydride, hydrazine hydrate, cyclic ketones, isocyanides and trimethylsilyl azide to yield a series of tetrazolo-spiroquinazolinone is described. The protocol offers the advantages of mild reaction conditions, one-pot operational simplicity, modest-good yields, easy work-up procedure, and environmental benignity.

Accumulation of human tau protein in the central nervous system is an outstanding feature of Alzheimer's Diseases and other tauopathies. Among the aggregate species, granular-shaped oligomers are recently reported as toxic species and associated with neuronal loss. Many interests have been focused on the reducing of these neurotoxic oligomers in tauopathies. It has been approved that peptides NAP (NAPVSIPQ) and SAL (SALLRSIPA), snipped from activity-dependent neurotrophic protein (ADNP) and activity-dependent neurotrophic factor (ADNF), protect brain against a wide range of toxins in neurodegenerative models. The neuroprotection mechanisms of NAP and SAL are under investigation. We report here that the aggregation pathway of human tau protein, in the presence of NAP or SAL, could be affected and moved toward the less granular-shaped species. Fluorophore binding assays, kinetic parameters and circular dichroism records, showed the presence of unusual aggregated species upon treatment with NAP or SAL, as well as hydrophobicity studies. Also, sizing and morphological investigation of aggregates, using dynamic scattered light and Atomic Force Microscopy, elucidated a significant reduction of granular-shaped oligomers under 50 nm. Furthermore, immunospecific detection of oligomers in SH-SY5Y cell line, using flow cytometric assessment supported our results. We conclude that one of the possible mechanisms of neuronal protection by NAP or SAL could be the attenuation of granular-shaped oligomeric tau under stress condition.

Mesoporous silica SBA-15 functionalized with 8-hydroxyquinoline-5-sulfonic acid (HQS-SBA-15) was used as a new recyclable nanocatalyst for the one-pot synthesis of 2-thiohydantoin derivatives under solvent-free conditions. The catalyst exhibited excellent recyclability at least for 3 times with a high catalytic activity.

We demonstrate in vitro cross-seeding of bovine serum albumin (BSA) in the presence of Aβ25-35 and their cytotoxic effects on microglial cells. To investigate the cross-seeding of BSA in the presence of Aβ25-35 fibrils, we examined how Aβ25-35 fibrils can function as seeds to trigger and accelerate BSA fibrillogenesis using ThT, intrinsic fluorescence, ANS fluorescence and transmission electron microscopy (TEM). Moreover, the effects of these fibrils on microglial viability were measured using MTT and Annexin V/propidium iodide (PI) staining. Although Aβ25-35 is toxic against microglia, it acted as seed and affected the aggregation pathway and accelerated the fibrillogenesis of BSA in vitro, resulted in an enhanced cytotoxic effect in comparison with Aβ25-35 or BSA alone. These observations thought to be helpful to understand the molecular mechanism of enhanced toxicity due to the coexistence of the aggregation prone proteins/peptides,. then cross-seeding effect on microglial cells that may involve in neurodegenerative diseases such as Alzheimer's disease (AD).

A simple and efficient synthesis of quinazolinone pseudo-peptide derivatives based on a new 3-amino-1,2,3,4-tetrahydro-4-oxoquinazoline-2-carboxylic acid via Ugi four-component reaction has been developed. This reaction was conducted under mild conditions with a broad scope of substrates.

A concise and efficient route for the diastereoselective synthesis of new and interesting α-hydrazino tetrazoles has been developed through a pseudo five-component domino reaction using the isocyanide-based one-pot multicomponent reaction. The products were obtained by a facile Ugi-azide pseudo five-component reaction of cyclic ketones, hydrazine hydrate, trimethylsilyl azide, and corresponding isocyanides without any catalyst in good yields and with high bond forming efficiency at room temperature.

A highly efficient domino Michael/cyclization reaction was developed for the synthesis of cyclopentanols and cyclopentenes with four and three stereogenic centers that were generated in one-pot reaction conditions with high diastereoselectivity. The reactions proceeded through a one-pot three-component reaction of β-nitrostyrenes, malononitrile and phenacyl bromide derivatives in basic media at room temperature.

New hydrazinyl pseudo-peptides have been obtained from Ugi four-component reaction (4CR). The 5-hydrazinyl-5-oxopentanoic acids used as starting materials were prepared by the reaction of hydrazides with anhydrides. Mild reaction conditions, high atom economy, bond-forming efficiency, and easy workup are advantages of this approach. The products have four amide bonds and high potential for H-bonding.

A sequential Ugi four-component reaction (4-CR)/CH activation using (diacetoxyiodo)benzene is reported. This process is a five-component reaction of aromatic aldehydes, aniline derivatives, isocyanides, phenylpropiolic acid (3-phenylprop-2-ynoic acid), and (diacetoxyiodo)benzene for the synthesis of 3-(diphenylmethylidene)-2,3-dihydro-1H-indol-2-ones. This procedure offers several advantages such as good yields, high bond-forming efficiency, selectivity, and short reaction times.

An efficient sequential four-component reaction of chromone carbaldehydes, Meldrum's acid, 4-hydroxyl coumarin or 6-methyl-4-hydroxyl-pyrone and primary alcohols is reported which leads to 5a-i in aqueous media. Replacing the primary alcohol with isopropyl alcohol and tert-butyl alcohol results in different products 10 and 11. The environmentally friendly features, good to high yields and easy work-up are advantages of this approach.

A novel and efficient method for the diastereoselective synthesis of α-hydrazine tetrazoles via an isocyanide-based multicomponent reaction is reported in good yields. The α-hydrazine tetrazoles were obtained by a facile azide Ugi four-component reaction (U-4CR) using cyclic ketones, trimethylsilyl azide, hydrazides, and corresponding isocyanide without any catalyst and with high bond forming efficiency at room temperature.

An efficient method for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from isothiocyanates and hydrazides through cyclodesulfurization in the presence of (O-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate) TBTU as an uronium coupling reagent has been developed. The present methodology offers several advantages, such as simple and easy work-up procedures, mild reaction conditions and it is environmentally benign.

We describe an efficient approach for the synthesis of N-substituted 2-alkenylamides in trifluoroethanol via an Ugi 4-component reaction in short reaction times. The use of a catalytic amount of sulfuric acid in trifluoroethanol gave the desired trifluoroethyl derivatives in good to high yields.

Water-soluble peptidocalix[4]arenes were synthesized by the introduction of arginine-rich narrow groove-binding residues at lower rims through solid-phase synthesis. The study of binding of these water-soluble bidentate ligands to well-matched and mismatched DNA duplexes by fluorescent titrations, ethidium bromide (EB) displacement assays, DNA-melting experiments, and circular dichroism (CD) analysis revealed a sequence-dependent groove-binding mechanism.

In our previous study on [Met5]-enkephalin analogues, [Met5]-enkephalin semicarbazide was found as a new enkephalin amide that produces antinociception even in ACE (Angiotensin Converting Enzyme) exposure in vivo. In the present work we examined the corresponding [Leu5]-enkephalin derivatives to confirm the influence of semicarbazide substitution. To prevent the enkephalins biodegradation animals were pretreated with a mixture of peptidase inhibitors. As assessed by tail-flick test no significant difference was detected between the produced antinociception by the [Leu5]-enkephalin derivatives. Based on our results both semicarbazide and ethylamide groups could preserve the provided analgesia after captopril (ACE inhibitor) omission from the peptidase inhibitors mixture. This work confirms that semicarbazide substitution on enkephalins yields ACE resistance antinociceptive peptides, nevertheless it may necessarily not enhance the peptides analgesic potencies.

Some new amidated fentanyl (=N-[1-(2-phenylethyl)piperidin-4-yl]-N-phenylpropanamide) analogs with a 4-(N-phenylamido)piperidine scaffold and additional amide bonds have been designed and synthesized through Ugi four-component reaction (Ugi-4CR). Good-to-high yields, diversity-oriented synthesis, and possible applications in drug discovery are advantages of this approach.

The metal nanoparticles (NPs) have been prepared using a water-in-oil microemulsion system of water/dioctyl sulfosuccinate sodium salt (aerosol-OT, AOT)/isooctane at 25 °C. Since the NPs produced in this system can endure forcing conditions (100 °C), this system has been used for the synthesis of nano-catalysts in the Heck reactions. FE-SEM, DLS, and UV/vis analyses have been used to characterize the surface morphology, size, and proof of the formation of all the prepared metal NPs, respectively. In addition, the effects of some reaction parameters (here, bases and solvents) were optimized. Differences in the catalytic properties of the synthesized NPs have also been investigated. Consequently, the Pd/Cu (4:1) bimetallic NP showed the highest activity in the C–C coupling reaction of the iodobenzene with the styrene, thus it is employed as the superior catalyst in this study. Therefore, the Pd/Cu (4:1) bimetallic NPs were further investigated using TEM and XRD analyses. This catalyst system is also reusable for six runs with very negligible reduction in the efficiency.

The vibrational wavenumbers and corresponding vibrational assignments of 2,2'-Ethylene bis(nitrilomethylidene) diphenol are examined theoretically using the Gaussian03 set of quantum chemistry codes. Comparison of the observed IR spectra with the calculated results by HartreeFock and B 3 lyp method is found in agreement with the experimental data. Theoretical infrared and Raman intensities are reported. The atomic orbital compositions of the frontier molecular orbital for SalenH 2 molecule is shown by the following figure.

diazabicyclo(2.2.2)octane (DABCO) was used as a catalyst for one-pot, three- component condensation reactions consisting of aromatic aldehydes, malononitrile and thiobarbituric acid in aqueous ethanol at room temperature. This method has the advantages of a simple operation,mild reaction conditions, high yields, by using a less toxic and low cost chemical as a catalyst.

The novel coumarin-3-carboxamides (¼ 2-oxo-2H-1-benzopyran-3-carboxamides) 5a - 5g containing lipophilic spacers were synthesized through the Ugi-four-component reaction (Scheme 1). The reactions of aromatic aldehydes 1, 4,4'-oxybis(benzenamine) or 4,4'-methylenebis(benzenamine) as diamine 2, coumarin-3-carboxylic acid (¼ 2-oxo-2H-benzopyran-3-carboxylic acid; 3), and alkyl isocyanides 4 lead to the desired substituted coumarin-3-carboxamides 5a - 5g at room temperature with high bond-forming efficiency. These novel coumarin derivatives exhibit brilliant fluorescence at 544 nm in CHCl3. Introduction. - Coumarins (¼ 2H-1-benzopyran-2-ones), and their analogs have attracted considerable attention in organic and medicinal chemistry (1). They have wide applications in food, pharmaceutical, and optical chemistry (2 - 4). Natural coumarins and their synthetic structural analogs show broad biological activities (5), such as antimicrobial (6), antitumor (7), and antiviral activities (8). Meanwhile, some coumarin derivatives could affect human immunodeficiency virus integrase inhibitors (9). Some coumarins have inhibitory activity against some serine proteases and matrix metalloproteases (MMPs) (10), and also act as a selective antiproliferative agent (11 - 14). It was shown that the existence of the amide group in coumarin-3-carboxamides (¼ 2-oxo-2H-1-benzopyran-3-carboxamides) improve the biological activity of these compounds (15 - 18). The presence of some nonpolar spacers could affect their ability to penetrate the bloodbrain barrier (19) (20). These compounds showed anti- Helicobacter pylori activity and also inhibition of breast cancer growth. Recently, some novel coumarin-3-carboxamides with effective anticoagulant activity (21) and also inhibitory activity against human monoamine oxidase (MAO) were synthesized (22). In continuation of our research work (23) to design novel one-pot reactions, we wish herein to report an approach to the synthesis of some new amidated coumarins which contain a lipophilic moiety and several amide bonds via the Ugi-four-component reaction (Ugi-4CR). Recently, Che, Yang and co-workers reported sequential Ugi-4CR

The CuI-catalyzed intramolecular oxa-DielsAlder reaction of 2-(prop-2-yn-1-yloxy)benzaldehydes as unactivated terminal alkynes with 4-hydroxy-6-methyl-2H-pyran-2-one is described. The reaction proceeds with remarkable chemoselectivity to yield pyranones 3 (Scheme 1). A theoretical investigation of the reaction in terms of HOMOLUMO interactions in the gas phase is also reported. The reaction could be regarded as an inverse-electron-demand DielsAlder cycloaddition. The theoretical results are in high agreement with the experimental evidences.

Dipeptidyl carboxypeptidase-I is an enzyme involved in the biological degradation of enkephalins. It has been suggested that C-terminal amidation of enkephalins enhances their resistance to dipeptidyl carboxypeptidase-I-mediated biodegradation. In this study, a novel [Met5]enkephalin amide (MEA) analogue [Met5]enkephalin (ME)-semicarbazide synthesized by another laboratory in our group was assessed for its antinociceptive effects compared with ME-ethylamide, MEA and ME, using tail flick test. To protect the administered drugs from biodegradation, rats were pretreated with peptidase inhibitors including amastatin, phosphoramidon and captopril. Then captopril (dipeptidyl carboxypeptidase-I inhibitor) was deleted from the peptidase inhibitors' combination for evaluating in vivo resistance of the synthetic drugs to dipeptidyl carboxypeptidase-I. According to the results, ME-semicarbazide and MEA were resistant enough to dipeptidyl carboxypeptidase-I to exert their strong antinociception following intrathecal administration even in the absence of captopril, whereas the antinociceptive effects produced by ME-ethylamide (10 nmol) were abolished in rats not pretreated with captopril, indicating that significant amounts of the ME-ethylamide were degraded by dipeptidyl carboxypeptidase-I. Replacement of the amide moiety of MEA with semicarbazide provides a new ME derivative, with high analgesic effects as well as more resistance to dipeptidyl carboxypeptidase-I-mediated biodegradation. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.

An efficient method for the stereoselective synthesis of 3-(diarylmethylene)-2-oxindoles and 3-(arylmethylene)-2-oxindoles via carbopalladation is described. In this approach, an Ugi-4-component reaction (4-CR) adduct was used as the starting material. A one-pot sequence involving intermolecular carbopalladation C–H activation/C–C bond formation efficiently afforded the oxindole derivatives.

An efficient strategy for the one-pot syntheses of indolo[1,2-a]quinoxalinones catalyzed by CuI have been developed. The procedures combine the Ugi four-component reaction of aldehydes, 2-iodoaniline, 2-indole carboxylic acid, and isocyanides followed by the copper-catalyzed intramolecular N-arylation of the Ugi product in one-pot procedure, which afford the desired products in good to very good yields.

The Michael-type addition of a 4-hydroxycoumarin (=4-hydroxy-2H-1-benzopyran-2-one) 1 to a β-nitrostyrene (=(2-nitroethenyl)benzene) 2 in the presence of AcONH4 leads to substituted (3E)-3-[amino(aryl)methylidene]chroman-2,4-diones (=(3E)-3-[amino(aryl)methylene]-2H-1-benzopyran-2,4(3H)-diones) 4 (Table 1). High yields, short reaction time, and easy workup are advantages of this novel one-pot three-component reaction.

The three-component reaction of primary amines, dialkyl acetylenedicarboxylates and β-nitrostyrene derivatives in the presence of Iron(III) chloride afforded 1,2,3,4-tetra-substituted pyrroles in high yields. These reactions could precede via domino Michael addition/cyclization process.