In this study, we examined the oxidation of (E)-2-hydroxy-1-naphthaldehyde oxime with lead tetraacetate in tetrahydrofuran that produced novel (E)-7a,8,9,10-tetrahydro-12H-naphtho[1,2-e]pyrrolo[2,1-b][1,3]oxazin-12-one oxime and 1-(pyrrolidin-1-yl)naphtho[1,2-d]isoxazole and known 7a,8,9,10-tetrahydro-12H-naphtho[1,2-e]pyrrolo-[2,1-b][1,3]oxazin-12-one in 15, 18, and 10% yields, respectively. The oxime is partially hydrolyzed to its corresponding ketone. Modifying the oxidants and reaction conditions did not improve the product yields. Based on previous studies in our laboratory, we proposed that the reactions proceed via the formation of an o-naphthoquinone nitrosomethide intermediate; 1D and 2D NMR, HRMS, IR, and UV-VIS spectra provided information that supported the structure of the products.

A series of new N,N '-diarylureas is reported as potential cannabinoid-1 (CB-1) receptor inhibitors. The synthesis of the new N,N '-diarylureas is achieved from the reaction of two substituted anilines with the aid of triphosgene. One aniline carries a pyrazol-1-yl or 1H-1,2,3-triazolyl or 2H-1,2,3-triazolyl propan-2-one group at position-3, while the other aniline is substituted by fluoro, bromo, methoxy, cyano, morpholino, or 4-methyl-2-nitro groups. All new compounds are investigated through density functional theory calculations, molecular docking, and molecular dynamics simulations, showing a strong ability to bind to the orthosteric pocket of the CB-1 receptor and to the allosteric position when CB1 is in complex with agonist AM841. The binding is comparable to that of the well-known CB-1 inhibitor PSNBAM-1. Especially, 1-{3-[2-(1H-pyrazol-1-yl)acetyl]phenyl}-3-(4-methyl-3-nitrophenyl)urea presents better theoretical results than PSNBAM-1.

[1,1′‐Binaphthalene]‐2,2′‐diol (BINOL) analog, [1,1′‐binaphthalene]‐4,4′‐diol, obtained by direct oxidative coupling of 1‐naphthol, is acylated to [1,1′‐binaphthalene]‐4,4′‐diyl diacetate and then rearranged by the Fries reaction to 1,1'‐{4,4'‐dihydroxy‐[1,1'‐binaphthalene]‐3,3'‐diyl}bis(ethan‐1‐one). Incorporation of aldehyde groups at the 3,3' positions of [1,1′‐binaphthalene]‐4,4′‐diol required oxidative coupling of 1‐methoxynaphthalene to 4,4′‐dimethoxy‐1,1′‐binaphthalene, bromination, formylation, and demethylation. Incorporation of benzoyl groups at the 3,3' positions of [1,1′‐binaphthalene]‐4,4′‐diol required subjecting either 1‐(4‐bromo‐1‐hydroxy‐2‐naphthyl)(phenyl)methanone to the Ullmann reaction conditions or 4,4′‐dimethoxy‐1,1′‐binaphthalene to the Friedel–Crafts reaction with benzoyl chloride. The 1,1′‐(4,4′‐dihydroxy‐1,1′‐binaphthalene‐3,3′‐diyl)dicarbonyls are converted to the corresponding dioximes, which then underwent cyclodehydration to the respective novel 5,5'‐binaphtho[2,1‐d]isoxazoles.

In this study, we examined the oxidation of (E)-2-hydroxy-1-naphthaldehyde oxime with lead tetraacetate in tetrahydrofuran that produced novel (E)-7a,8,9,10-tetrahydro-12H-naphtho[1,2-e]pyrrolo[2,1-b][1,3]oxazin-12-one oxime and 1-(pyrrolidin-1-yl)naphtho[1,2-d]isoxazole, and, known 7a,8,9,10-tetrahydro-12H-naphtho[1,2-e]pyrrolo-[2,1-b][1,3]oxazin-12-one, in 15, 18 and 10% yields, respectively. The oxime is readily hydrolysed to its corresponding ketone. Modifying the oxidants and reaction conditions did not improve the product yields. Based on previous studies in our laboratory, we proposed that the reactions proceed via the formation of an o-naphthoquinone nitrosomethide intermediate. 1H and 13C NMR, HRMS, IR, and UV-VIS spectra provided information that supported the structure of the products.

For the synthesis of 1-(2-(1H-pyrrole-2-carbonyl)phenyl)-3-(4-methoxyphenyl)urea, the final product, two different methods were used, in one or two steps, from (2-aminophenyl)(1H-pyrrol-2-yl)methanone. The one-step synthesis entailed a carbonylation reaction with 1/3 equivalent of triphosgene in the presence of two equivalents of trimethylamine, followed by the addition of 4-methoxyaniline to the in situ generated aryl isocyanate. The two-step synthesis required first the preparation of phenyl(2-(1H-pyrrole-2-carbonyl)phenyl)carbamate and then a substitution reaction by 4-methoxyaniline. The first method produced the final product in 72% yield, which was the best yield. The structure of the final product was confirmed by FTIR, UV-VIS, 1H and 13C NMR spectroscopy and high resolution mass spectrometry.

Naphtho[1,8-de][1,2]oxazin-4-ol and its acyl or benzyl derivatives ring open to various 2,8-dihydroxy-1-naphthonitriles, which, through (de)protection protocols and reduction, afford the target (E)-2-hydroxy-8-methoxy-1-naphthaldehyde. This was converted to its corresponding oxime, which was oxidatively o-cyclized with phenyliodine(III) diacetate (PIDA) to 9-methoxynaphtho[1,2-d]isoxazole 2-oxide. The latter, in deuterated DMSO at room temperature, was rearranged to its isomer 2-hydroxy-8-methoxy(naphthalen-1-yl)nitrile oxide. The isomerization was detected by time-course plot 1H NMR spectroscopy and further identified from its 13C NMR and HRMS spectra. The nitrile oxide was stable in (non)deuterated DMSO for at least 18 h. A 3,4-bis(2-hydroxy-8-methoxynaphthalen-1-yl)-1,2,5-oxadiazole 2-oxide, as a dimerization product or an isocyanate as a rearrangement isomer, was ruled out, the former by its HRMS spectrum and the latter by its 1,3-dipolar cycloaddition reactions to substituted isoxazoles.

Naphtho[1,8-de][1,2]oxazin-4-ol and its acyl or benzyl derivatives ring open to various 2,8-dihydroxy-1-naphthonitriles, that undergo methylation, reduction, demethylation and debenzylation reactions, to afford the target compound (E)-2-hydroxy-8-methoxy-1-naphthaldehyde. The best overall yield of the latter was 28.7%. This compound was converted to its corresponding (E)-2-hydroxy-8-methoxy-1-naphthaldehyde ox-ime, which was oxidatively o-cyclized with phenyliodine(III) diacetate (PIDA) to 9-methoxynaphtho[1,2-d]isoxazole 2-oxide. The latter in deuterated DMSO, at room temperature, rearranged to its isomer to 2-hydroxy-8-methoxy(naphthalen-1-yl)nitrile oxide. The isomeriza-tion was detected by a time-course plot 1H NMR spectroscopy and further identified from its13C NMR and HRMS spectra. The nitrile oxide was stable in (non)deuterated DMSO for at least 18 hours. A 3,4-bis(2-hydroxy-8-methoxynaphthalen-1-yl)-1,2,5-oxadiazole 2-oxide as a dimeriza-tion product or an isocyanate as a rearrangement isomer were both ruled out, the former by the absence of the relevant molecular ion in its HRMS spectrum while the latter by 1,3-dipolar cy-cloaddition reactions with various dipolarophiles that gave substituted isoxazoles, thus con-firming the nitrile oxide structure.

2-Hydroxy-1-naphthaldehyde oxime was oxidized by AgO (or Ag2O), in presence of N-methyl morpholine N-oxide (NMMO), to the title spiro adduct-dimer (±)-Spiro{naphthalene-1(2H),4'-(naphtho[2',1':2,3]pyrano[4,5-c]furazan)}-2-one-11'-oxide by a Diels-Alder(D-A) type self-cycloaddition, through the agency of an o-naphthoquinone nitrosomethide (o-NQM). Moreover, 2-hydroxy-8-methoxy-1-naphthaldehyde oxime was prepared and subjected to the same oxidation conditions. Its sterically guided result, 9-methoxynaphtho[1,2-d]isoxazole, was isolated, instead of the expected spiro adduct. The peri intramolecular H bonding in the oxime is considered to have a key contribution to the outcome. Geometry and energy features of the oxidant- and stereo-guided selectivity of both oxidation outcomes have been explored by DFT, perturbation theory and coupled cluster calculations. The reaction free energy of the D-A intermolecular cycloaddition is calculated at -82.0 kcal/mol, indicating its predominance over the intramolecular cyclization of ca. -37.6 kcal/mol. The cycloaddition is facilitated by NMMO through dipolar interactions and hydrogen bonding with both metal complexes and o-NQM. The 8(peri)-OMe substitution of the reactant oxime sterically impedes formation of the spiro adduct, instead it undergoes a more facile cyclodehydration to the isoxazole structure by ca. 4.9 kcal/mol.

In this study, we considered the reaction of (E)-1-[(2-phenylhydrazono)methyl]naphthalen-2-ol with iodobenzene diacetate in dichloromethane-produced novel 3-phenyl-3H-naphtho[1,2-e][1,2,3]oxadiazine in 11% yield. By analogy to previously published work, we suggested that the reaction proceeds via the intermediacy of an o-naphthoquinone azomethide that undergoes conjugated 6π-electrocylization to produce the product. 1D, 2D NMR, HRMS, IR, and UV-VIS spectra provided information that supported the structure of the product.

The synthesis of novel pyrrolo[1,2-c][1,3]benzodiazepine and pyrrolo[3,2-c]- [1]benzazepine ring systems from (2-aminophenyl)(1H-pyrrol-2-yl)methanone and 2-[(1H-pyrrol-2-yl)methyl]aniline is presented, utilizing triphosgene as carbonylation-cyclization reagent for the formation of the 7-membered heterocycle. A study of the reaction shows that small changes in the reaction conditions affect dramatically the course of the reaction. Acidity as well as aqueous workup play significant roles in the reaction outcome, directing product formation and revealing important aspects of triphosgene mediated cyclizations.

Neurotensin (NT) (pGlu-Leu-Tyr-Glu-Asn-Lys-Pro-Arg-Arg-Pro-Tyr-Ile-Leu) exerts a dual function as a neurotransmitter/neuromodulator in the central nervous system and as a hormone/cellular mediator in periphery. This dual function of NT establishes a connection between brain and peripheral tissues that renders this peptide a central player in energy homeostasis. Many biological actions of NT are mediated through its interaction with three types of NT receptors (NTS receptors). Despite its role in energy homeostasis, NT has a short half-life that hampers further determination of the biological actions of this peptide and its receptors in brain and periphery. The short half-life of NT is due to the proteolytic degradation of its C-terminal side by several endopeptidases. Therefore, it is important to synthesize NT analogues with resistant bonds against metabolic deactivation. Based on these findings, we herein report the synthesis of ten linear, two cyclic and two dimeric analogues of NT with modifications in its structure that improve their metabolic stability, while retaining the ability to bind to NTS receptors. Modifications at position 11 (introduction of D-Tyrosine (OEthyl) [D-Tyr(Et)] or D-1-naphtylalanine [D-1-Nal] were combined with introduction of a L-Lysine or a D-Arginine at positions 8 or 9, and 1-[2-(aminophenyl)-2-oxoethyl]-1H-pyrrole-2-carboxylic acid (AOPC) at positions 7 or 8, resulting in compounds NT4-NT21. AOPC is an unnatural amino acid with promise in applications as a building block for the synthesis of peptidomimetic compounds. To biologically evaluate these analogues, we determined their plasma stability and their binding affinities to type 1 NT receptor (NTS1), endogenously expressed in HT-29 cells, Among the fourteen NT analogues, compounds, NT5, NT6, and NT8, which have D-Tyr(Et) at position 11, bound to NTS1 in a dose-response manner and with relatively high affinity but still lower than that of the natural peptide. Despite their lower binding affinities compared to NT, the NT5, NT6, and NT8 exhibited a remarkably higher stability, as a result of their chemistry, which provides protection from enzymatic activity. These results will set the basis for the rational design of novel NT molecules with improved pharmacological properties and enhanced enzymatic stability.

The review deals with the metal-catalyzed synthetic methods used for the construction of 5-membered nitrogen-containing aromatic and nonaromatic heterocycles with one to three nitrogen atoms, published in the years 2008–2017. The methodology is based on the metalcatalyzed activation of the alkyl C(sp3)–H, alkenyl C(sp2)–H, and terminal alkyne C(sp)–H bonds of appropriate precursors in order to perform intermolecular and intramolecular reactions. These bond forming reactions include C(sp3)–C(sp2), C(sp2)–C(sp2), and C(sp2)–C(sp) coupling, hydroamination at C(sp2)–H and C(sp)–H bonds, and oxidative amination of alkyl C(sp3)–H, alkenyl and arene C(sp2)–H, and terminal alkyne C(sp)–H bonds. Two further bond forming methods are intramolecular nitrenoid–arene C(sp2) coupling and cycloaddition reactions. Transition metals are systematically used in these synthetic methods, and only in a few cases Lewis acids are used as catalysts. In general, the metal-catalyzed cyclizations leading to five-membered heterocycles are very efficient and particularly useful in the synthesis of natural and unnatural biologically active products.

Mental disorders are neuropsychiatric conditions that are marked by unusual or irregular thinking, feelings, or behavior, and lead to distress and/or impaired functions. Major psychiatric conditions are depression, anxiety, and psychoses of various types. Their etiopathogeneses, of a primary or secondary origin, are associated with genetic and environmental factors. They are commonly treated with psychoactive drugs (also known as psychotropics), which target serotonin, dopamine, norepinephrine, glutamate, and nuclear receptors (NRs), including retinoic acid receptor-related orphan receptors (RORs) and other receptors in the central nervous system (CNS). Herein we present a diverse array of isoxazole derivatives, among which are some prominent marketed drugs. Some of the derivatives and forms, including N-oxides, are under either (pre)clinical evaluation or patent protection as new generation of psychotropics, and a few have effective blood-brain barrier (BBB) permeability. Various drug-like isoxazol(in)es and their structural features and efficiency, modified through scaffold hopping, are described and discussed in the context of treating neuropsychiatric conditions.

A novel nitration and oxidation reaction sequence of 2-acetyl-1-naphthol benzoylhydrazones with CAN is presented. There is strong indication that nitration precedes an oxidative rearrangement to 1,2-diacyl-4-nitronaphthalenes or oxidative electrocyclisation to 3-methyl-5-nitronaphtho[2,1-d ]isoxazole. Condensation of 1,2-diacyl-4-nitronaphthalenes with hydrazine hydrate yields 1,4-disubstituted benzo[ f ]phthalazines.

Pyrrolo[1,4]benzodiazepines are tricyclic compounds that are considered "privileged structures" since they possess a wide range of biological activities. The first encounter with these molecules was the isolation of anthramycin from cultures of Streptomyces, followed by determination of the X-ray crystal structure of the molecule and a study of its interaction with DNA. This opened up an intensive synthetic and biological study of the pyrrolo[2,1-c][1,4]benzodiazepines that has culminated in the development of the dimer SJG-136, at present in Phase II clinical trials. The synthetic efforts have brought to light some new synthetic methodology, while the contemporary work is focused on building trimeric pyrrolo[2,1-c][1,4]benzodiazepines linked together by various heterocyclic and aliphatic chains. It is the broad spectrum of biological activities of pyrrolo[1,2-a][1,4]benzodiazepines that has maintained the interest of researchers to date whereas several derivatives of the even less studied pyrrolo[1,2-d][1,4]benzodiazepines were found to be potent non-nucleoside HIV-1 reverse transcriptase inhibitors. The present review is an update on the synthesis of pyrrolo[2,1-c][1,4]benzodiazepines since the last major review of 2011, while the overview of the synthesis of the other two tricyclic isomers is comprehensive.

A simple and efficient one-pot cascade reaction for the regioselective synthesis oftransorcis/trans-2,3-disubstituted 2,3-dihydrobenzofurans, is described.

AbstractThe yields using propanoate (IV) as starting material are much higher than the corresponding yields using propanoate (I) (for example synthesis of compound (III)).

A new method is presented for the regioselective one-pot synthesis of 3-substituted 2,3-dihydrobenzofurans from 2-bromo-1-{2-[(triisopropylsilyl)oxy]phenyl}ethyl nitrate by fluoride-induced desilylation leading to o-quinone methide generation, Michael addition of different C, N, O, and S nucleophiles, and intramolecular 5-exo-tet elimination of a bromide anion. The method has potential synthetic applications in drug discovery.