Seppo Kaltia

Hydroperoxide formation during autoxidation of conjugated linoleic acid methyl ester

The aim of this study was to investigate whether hydroperoxides are formed in the autoxidation of conjugated linoleic acid (CLA) methyl ester both in the presence and absence of α-tocopherol. The existence of hydroperoxide protons was confirmed by D2O exchange and by chemoselective reduction of the hydroperoxide groups into hydroxyl groups using NaBH4. These experiments were followed by nuclear magnetic resonance (NMR) spectroscopy. The 13C and 1HNMR spectra of a mixture of 9-hydroper-oxy-10-trans,12-cis-octadecadienoic acid methyl ester (9-OOH) and 13-hydroperoxy-9-cis, 11-trans-octadecadienoic acid methyl ester (13-OOH), which are formed during the autoxidation of methyl linoleate, were studied in detail to allow the comparison between the two linoleate hydroperoxides and the CLA methyl ester hydroperoxides. The 13CNMR spectra of samples enriched with one of the two linoleate hydroperoxide isomers were assigned using 2D NMR techniques, namely Correlated Spectroscopy (COSY), gradient Heteronuclear Multiple Bond Correlation (gHMBC), and gradient Heteronuclear Single Quantum Correlation (gHSQC). The 13C and 1H NMR experiments performed in this study show that hydroperoxides are formed during the autoxidation of CLA methyl ester both in the presence and absence of α-tocopherol and that the major isomers of CLA methyl ester hydroperoxides have a conjugated monohydroperoxydiene structure similar to that in linoleate hydroperoxides.

The phase transfer catalysed synthesis of isoflavone-O-glucosides

Daidzin 1, genistin 2, ononin 3 and sissotrin 4 are the major products of the phase transfer catalysed reaction between the isoflavone aglycones daidzein, genistein, formononetin and biochanin A, respectively, and 1-bromo-2,3,4,6-tetra-O-acetyl-α-glucopyranose. Complete proton and carbon NMR assignments are presented for compounds 1–4.

α,β-Dibenzyl-γ-butyrolactone lignan alcohols: total synthesis of (±)-7′-hydroxyenterolactone, (±)-7′-hydroxymatairesinol and (±)-8-hydroxyenterolactone

Abstract Two trans-α,β-dibenzyl-γ-butyrolactone lignans carrying a hydroxyl group at the β-benzylic carbon atom and a α-hydroxy α,β-dibenzyl-γ-butyrolactone lignan were synthesized in racemic form using the tandem conjugate addition reaction to construct the basic lignan skeleton. Subsequent reaction steps involved either a catalytic reduction of the regenerated keto group to the alcohol, or a hydrogenolysis to benzylic methylene followed by lactone enolate formation and oxidation to give the α-hydroxybutyrolactones. These procedures were applied for the synthesis of 7′-hydroxyenterolactones and 7′-hydroxymatairesinols, and 8-hydroxyenterolactones, respectively. The diastereomeric mixtures of these compounds were separated either by HPLC techniques or column chromatography and the structures were elucidated using NMR spectroscopy.

A study of 1,5-hydrogen shift and cyclization reactions of an alkali isomerized methyl linolenoate

Abstract Heating a mixture formed by alkali isomerization of methyl linolenoate ( 1 ) produces a complex mixture with the bicyclic hexahydroindenoic esters 4β-(7-methoxycarbonylheptyl)-5α-methyl-2,3,3aα,4,5,7aαhexahydroindene (CL5) and 4β-ethyl-5α-(6-methoxycarbonylhexyl)-2,3,3aα,4,5,7aα-hexahydroindene (CL6) as main components. Similar isomerization reactions of three synthetic model compounds, methyl 9 Z ,13 E ,15 Z -octadecatrienoate ( 2 ), 9 Z ,14 E ,16 E -octadecatrienoate ( 4 ) and 9 Z ,11 E ,15 Z -octadecatrienoate ( 5 ) corroborated the results obtained with alkali isomerized methyl linolenoate.

1,5-Hydrogen shift and other isomerization reactions of certain ethyl octadecatrienoates

Abstract Four new octadecatrienoic acid ethyl esters (4–7) were synthesized. On heating these undergo cyclization, via an intramolecular Diels-Alder (IMDA) reaction, mainly to stereoisomers of ethyl 4-(5-pentyl-1,2,3,3a,4,5,7a-hexahydroindenyl)-butanoate (CP-1, CP-2, CP-3, CP-4 and CP-5) and 3-(6-pentyl-1,2,3,4,4a,5,6,8a-octahydronaphthyl)propanoate. 1,5-Sigmatropic hydrogen shift reactions of the trienoic esters 4–7, all possessing a conjugated Z,E structure, precede the IMDA reactions. The 1,5-hydrogen shift reaction occurs in Z,E dienoic structures at a lower temperature than the Z,E to E,E isomerization.

Photochemical decomposition of midazolam. III — Isolation and identification of products in aqueous solutions

Midazolam, 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5- a][1,4]benzodiazepine, decomposes photochemically in aqueous solution both under irradiation from a high-pressure mercury lamp and in normal daylight. The main decomposition product under the artificial radiation was 6-(8-chloro-1-methyl-4,5-dihydro-2,5,10b-triaza-benzo[e]-azulen -6-ylidene)- cyclohexa-2,4-dienone, which was not present in the solution exposed to daylight. 6-Chloro-2-methyl-4-(2-fluorophenyl)quinazoline was formed in both irradiation experiments and was the main decomposition product in normal daylight. Several minor products were formed in both solutions, the amounts depending on the pH of the solution. Only one decomposition product was formed in acidic solutions (pH < 2) irradiated with the high-pressure mercury lamp but numerous products were formed at higher pH.

Cyclopinolenic acids: Synthesis, derivatives and thermal properties

The two isomeric cyclopinolenic acids (CP-1 and CP-2), components of distilled tall oil, have been synthesized by means of an intramolecular Diels-Alder reaction of isomers of 5,10,12-octadecatrienoic esters, themselves synthesized in a stereocontrolled manner. The 5cis,10-trans,12trans isomer cyclizes at 200°C to a 1:3 mixture of esters of CP-1 and CP-2. At 200°C, the 5cis,10trans,12cis isomer is unreactive, but at 240°C it gives the same CP-1 + CP-2 ester mixture, presumably by way of prior isomerization to the 5cis,10trans,12trans isomer. A subambient thermal study of CP-1 and CP-2 and their derivatives shows that the compounds, excluding CP-1, lack crystalline structures or melting points, and display glass transitions only, below −80°C for esters and below −50°C for the carboxylic acids.

SYNTHESIS OF ISOPULO'UPONE

Abstract Two routes are reported for the synthesis of the title marine metabolite 1. The routes converge at the trienoic aldehyde 4, and are completed by chain extension to the tetraenoic ketone 5 and intramolecular Diels-Alder cyclization. - Daylight lamp irradiation offers a convenient means for converting a cis/trans mixture from a Wittig reaction into the pure trans isomer.

Intramolecular Diels-Alder reaction of 5,10,12-(5E,10E,12E)-octadecatrienoic and 2,7,9-(2E,7E,9E)-pentadecatrienoic esters

Abstract In stereochemical outcome of intramolecular Diels-Alder reactions, the non-activated 5,10,12-octadecatrienoate system is intermediate between the activated 2,7,9-isomer and the parent hydrocarbon 1,6,8-nonatriene

Separation and purification of pinolenic acid by the iodolactonization method

The separation of pinolenic acid from distilled tall oil fatty acid by the iodolactonization method was studied. The significance of prefractionation of tall oils and details of the iodolactonization procedure for the pinolenic acid purity achieved is discussed.