Wieslaw Z. Antkowiak

Synthesis of 2-(2′-hydroxyphenyl)pyridine-N-oxide and its thermal decomposition as a model reaction of orellanine deoxidation

Abstract 2-Methoxyphenylmagnesium bromide was reacted with 2-nitropyridine-N-oxide and demethylated to give 2-(2′-hydroxyphenyl)pyridine-N-oxide (II) which was found to undergo a thermal deoxidation to the free base (VI); the process is interpreted as a [1.5] oxygen shift followed by decomposition of the hydroperoxide intermediate.

Solvent effect on the reactivity of 1,10-phenanthroline-5,6-dione towards diazomethane

Abstract In an aprotic medium, such as THF, Et 2 O or CH 2 Cl 2 , the reaction of 1,10-phenanthroline-5,6-dione with diazomethane gave 5,6-methylenedioxy-1,10-phenanthroline as the only product. In contrast, in a protic solvent, such as 2-propanol or ethanol, the nucleophilic attack of CH 2 N 2 occurred on carbonyl carbons, resulting in the formation of dispiro[5,6-dihydro-1,10-phenanthroline-5,6-dioxirane] as the main product. When the reaction with CH 2 N 2 was carried out in methanol, the only product which could be isolated from the reaction mixture, dimethyl 2,2′-bipyridine-3,3′-dicarboxylate, resulted from a break of the C(5)–C(6) bridge.

Structure studies of the metabolites of Paxillus involutus

The chemical components of Paxillus involutus were isolated from the freshly collected fruit bodies. Mainly on the basis of the NMR and ESI-MS data, the structures of the unknown pigments were determined as 4-(3,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-2-(2-pyrrolidon-5-yl)-4-cyclopentene-1,3-dione and (4Z)-5-hydroxy-2-(3,4-dihydroxyphenyl)-5-(4-hydroxyphenyl)-2,4-pentadien-4-olide, respectively.

Crystal structure of orellanine hydrate

Orellanine hydrate crystallizes in the monoclinic space groupC2/c with unit cell parametersa=11.516(1) Å,b=8.573(1) Å,c=11.167(2) Å,β=110.92(1)°. The finalR andRw equal 0.041 and 0.046, respectively. The water molecule in the hydrate binds bothN-oxide oxygens of the orellanine molecule by hydrogen bonds, thus fixing the conformation. The hydrate so formed occupies a special position on a twofold axis which passes through the midpoint of the C2-C2′ bond distance and the OW atom. Both of the hydroxy-groups participate also in intermolecular hydrogen bonds. As a consequence of the rigid hydrogen bonded network, the dihedral angle between these two pyridil rings of the orellanine molecule is equal to 90.20(5)°.

A Comparison of the Enamino Carbonyl Conjugation Efficiency for Hydrogen Bonding Formation in Pyridone and Dihydropyridone Systems

The crystal structures of two compounds containing enaminone heterodiene systems and forming intermolecular hydrogen bonds N-H·O are reported: 1) 3-ethoxycarbonyl-2-methyl-4-pyridone (hereafter ETPY) and 2) 3-ethoxycarbonyl-2-phenyl-6-methoxycarbonyl-5,6-di-hydro-4-pyridone (hereafter EPPY). The crystal packing is controlled by intermolecular hydro gen bonds N-H·O = C connecting the heteroconjugated enaminone groups in infinite chains. In ETPY crystals the intermolecular hydrogen bond involves the heterodienic pathway with the highest π-delocalization that is effective for a very short N·O distance of 2.701(9) Å (average from two molecules in the asymmetric unit). Probably due to the steric hindrance, the hydrogen bond in EPPY is formed following the heterodienic pathway that involves the ester C = O group, although π-delocalization along this pathway is less than that along the pyridone-part pathway resulting in a longer N·O distance of 2.886(3) Å

Is the formation of 1,10-phenanthroline di-N-oxide possible?

Abstract 5,6-Dichloro-5,6-dihydro-1,10-phenanthroline (2) was found as an additional product of the hypochlorous acid action on 1,10-phenanthroline. When treated with MCPBA the product of the chlorine addition yielded a corresponding di-N-oxide 3, which readily lost hydrogen chloride under the influence of sodium isopropoxide. The resulting monchloro di-N-oxide 5 molecules (assumed to be flat) revealed a satisfactory stability unless the neutral or basic solution was made acidic.

X-ray and spectroscopic investigation of 2-(2-hydroxyphenyl)pyridine-1-oxide

A strong intramolecular hydrogen bond O-H⋯O, found by spectroscopic methods and proved by X-ray analysis, keeps the two planar fragments of the molecule twisted. The angle between the least-squares planes of these fragments is 38.2(1)°. The influence of the conformational rigidity of the molecule on the spectroscopic properties of the title compound is discussed in comparison with its methyl ether and free base.

Synthesis of 2,3-disubstituted 4-pyridone from a β-aminocarboxylate derivative and acetoacetate

Abstract The reaction of diethyl aminomethylenemalonate with ethyl acetoacetate proceeded, when catalyzed by anhydrous hydrogen chloride, toward a respectively substituted α‐ instead of γ‐pyridone derivative formation, contrary to the literature report. Additionally, it was found that the amine used as a starting component in this reaction showed a great tendency to autocondensation under the influence of anhydrous hydrogen chloride to yield 5‐ethoxycarbonyl‐2‐pyridone. The most convenient method to prepare 4‐pyridone 2,3‐disubstituted derivative appeared to be a three‐step synthesis, starting from a chain enamine formation, which was subjected to cyclization, followed by oxidation of the last intermediate. The usefulness of the stepwise synthesis was demonstrated on the 3‐ethoxycarbonyl‐2‐methyl‐4‐pyridone preparation as an example.

Chapter 2 Alkaloids from Mushroomsroza

Publisher Summary This chapter discusses that the usage of the word mushroom varies considerably. Usually the word is restricted to edible macrofungi with a cap borne on a stem, whereas large fungi with poisonous fruiting bodies are designated as toadstools. In this chapter the word mushroom is used as referring to that part of fungi whose size is sufficient for them to be recognized without help of lens. Mushrooms found to be source of alkaloids occupy only a small taxonomic range. The species for which a particular alkaloid structure is characteristic are closely related and is comprised within the next higher taxon, genus, or family. The fungi world is a rich but only partly explored source of nitrogen-containing metabolities of various structures. However, apart from those which are essential for all forms of life, many secondary metabolites have been identified in the lower fungi. The alkaloids are discussed according to their structural features; however, the intention is also to locate the alkaloid source of fungi in the chapter.

The Effect of Different Hydrogen Bonding Schemes on Melting Points of Two Isomeric 2-Hydroxy-bornane-3-carboxylic Acids

Abstract The crystal structures of two isomeric compounds, 2-endo-hydroxybornane-3-endo-carboxylic acid and 2 -exo -hydroxybomane-3 -endo-carboxylic acid, have been determined by X-ray single crystal analysis. The only difference between these two compounds is the disposition of the 2-hydroxy group with respect to the bomane skeleton. Both compounds show quite different hydrogen bonding schemes. In the endo-hydroxy-endo-carboxy isomer there is one intramolecular and one intermolecular hydrogen bond, which connects molecules into infinite chains, while in the exo-hydroxy-endo-carboxy isomer there are two intermolecular hydrogen bonds that form a more stable architecture of two kinds of chains which interconnect to close rings comprising four molecules. Due to these differences the melting point of 2 is ca. 30° higher than for 1 .