Dye-sensitized Photooxygenation Research Articles

Isolation and reactions of 7a-hydroperoxy-1,2,3,4,5,6,7,7a,12b-octahydroindolo[2,3-a]quinolizine

Dye-sensitized photo-oxygenation of the octahydroindoloquinolizine (1) provided the title compound (2) which was converted into the corresponding spiro-oxindole N-oxide (3), the hydroxyindolenine (4), into (5), which is the N-5-oxide of (4), the oxo-amide (6), the quinolone (7) and the 1,4-oxazine derivative (8) under various conditions, whereas the 2-acylindole (11) was obtained from the chloride (10).

Structures of the artabsinolides; photo-oxygenation studies on artabsin

The structure and stereochemistry of four new guaianolides from Artemisia absinthium, named artabsinolides A, B, C, and D, have been established. They were synthesized via rearrangement or reduction of the endo-peroxides resulting from dye-sensitized photo-oxygenation of the main constituent of the plant, artabsin (1).

Dye-sensitized photo-oxygenation of the Aspidosperma alkaloids vincadifformine and tabersonine. A new, convenient approach to vincamine

The dye-sensitized photo-oxygenation of (–)-vincadifformine (1) and (–)-tabersonine (3) is described. Reaction takes place through the intermediate formation of 16-hydroperoxyindolenines, which decompose to give 2,16-seco-products or which can be efficently trapped by reductants to give a new stereoselective synthesis of the 16-hydroxy-[3H]indoles (10) and (14). These compounds are the key precursors to the eburnane alkaloids vincamine (4) and Δ14-vincamine (6). Suitable experimental conditions give compounds (4) and (6) in good yields directly from their Aspidosperma precursor.

Dye-sensitized photooxygenation of 4,6-di-tert-butyl-2-diazo-1,2-benzoquinone

Dye-sensitized photooxygenation of 4,6-di-tert-butyl-2-diazo-1,2-benzoquinone

Chemistry of singlet oxygen. 34. Unexpected solvent deuterium isotope effects on the lifetime of singlet molecular oxygen (1.DELTA.g)

Effects of solvent (acetone, acetonitrile, benzene, chloroform) deuteration on dye-sensitized photooxygenation were studied. A direct correlation was not found between solvent isotope effects on the lifetime of singlet oxygen and the optical densities of the solvent in regions that correspond to /sup 1/..delta../sub g/(V=O) ..-->.. 3..sigma../sub g//sup -/ transitions where oxygen is left in its ground electronic state with varying amounts of vibrational quanta. (DLC)

Dye-sensitized photooxygenation of tyrptophan: 3a-Hydroperoxypyrroloindole as a labile precursor of formylkynurenine.

The isolation, structure determination, and reactivity of the tricyclic labile hydroperoxides 10 and 2 obtained by dye-sensitized photooxygenation of L-, D-, and DL-tryptophan and Nb-methoxycarbonyltryptophan ester are reported. The tricyclic hydroperoxide 10, under appropriate conditions, was easily convertible to formylkynurenine. Plausible mechanisms for these transformations are discussed.

Dye-sensitized photo-oxygenation of tryptophan to give N′-formylkynurenine

Exclusive conversion of the tricyclic hydroperoxide (1) into N′-formylkynurenine (2) has been found to occur in Na2CO3–AcOH (pH 7) and the methylene blue-sensitized photo-oxygenation of tryptophan in the same system has given N′-formylkynurenine as the sole product, in contrast with the reaction in water, which gave compound (1).

Photosensitized oxygenation of phenylpyruvic acid derivatives as a model for p-hydroxyphenylpyruvate dioxygenase

Dye-sensitized photooxygenation of enol ethers of methyl phenylpyruvates ( 3 ) produced diendoperoxides 4 in aprotic solvents, whereas in methanol hydroxylated product 6 was obtained. The reaction scheme is discussed in comparison uith that for the enzymic transformation.

Ene-reaction en serie organometallique. Actione de l'oxygene singulet sur les dimethyl-1,1 sila (ou germa) cyclopentenes-3

Zusammenfassung The dye-sensitized photooxygenation of the title compounds leads by an “ene-reaction” mechanism to hydroperoxides with a shifted double bond which, treated by NaBH4, give 1,1-dimethyl-1-silacyclopent-4-ene-3-ol and 1,1-dimethyl-1-germacyclopent-4-ene-3-ol, respectively.

The Transformation of Jervine into 18-Functional C-Nor-D-homosteroids

Abstract N,O-Diacetyldeoxojervine, obtained by the Wolff-Kishner reduction of jervine followed by acetylation, has been catalytically hydrogenated to (22S,25S)-N,3-O-diacetyl-5α-veratranine-3β,3β-diol. Irradiation in benzene containing mercury(II) oxide and iodine afforded 20-formyl-17β-ethyl-12α-etiojervan-3β-ol 3-acetate which was converted into 17β-ethyl-3β-hydroxy-12α-etiojervan-20-one 3-acetate by dye-sensitized photo-oxygenation of the corresponding morpholine enamine. Reduction to 17β-ethyl-12α-etiojervane-3β,20β-diol 3-acetate with sodium borohydride followed by irradiation in benzene in the presence of mercury(II) oxide and iodine afforded an 18-functional C-nor-D-homosteroid, (20R)-18,20-epoxy-17β-ethyl-12α-etiojervane-3β,20β-diol. The configuration of the methyl group on the tetrahydrofuran ring has been shown to be α on the basis of the NMR spectrum, confirming a previous assignment.

Reaction of protoberberine-type alkaloids. Part 13. Biogenetic conversion of protoberberine alkaloids into phthalideisoquinoline alkaloids

A new convenient and biogenetic-type conversion of the protoberberine alkaloids into the phthalideisoquinoline alkaloids is described. The phthalideisoquinoline 5,6-dimethoxy-3-(6,7-dimethoxyisoquinolin-1-yl)isobenzofuran-1(3H)-one (4) was derived from 8-norcoralyne chloride (1)via 13-oxidonorcoralyne (3) in a one-pot reaction consisting of dye-sensitized photo-oxygenation followed by treatment with sodium borohydride. The conversion of berberine chloride into (±)-β-hydrastine (21) was performed by a reaction sequence involving conversion of 8,13a-epidioxy-9,10-dimethoxy-2,3-methylenedioxy-13-oxo-5,6,13,13a-tetrahydro-8H-dibenzo[a,g]quinolizine (9) into 1-(2-carboxy-3,4-dimethoxybenzoyl)-3,4-dihydro-6,7-(methylenedioxy)isoquinoline (11) using pyridinium chloride, followed by methylation and reductive cyclization.

Chemistry of singlet oxygen. 31. Low-temperature nuclear magnetic resonance studies of dye-sensitized photooxygenation of imidazoles: direct observation of unstable 2,5-endoperoxide intermediates

Chemistry of singlet oxygen. 31. Low-temperature nuclear magnetic resonance studies of dye-sensitized photooxygenation of imidazoles: direct observation of unstable 2,5-endoperoxide intermediates

ChemInform Abstract: PREFERENCE FOR SYN ENE ADDITIONS OF 1O2 TO TRISUBSTITUTED, ACYCLIC OLEFINS

AbstractDie farbstoffsensibilisierte Photooxidation der E‐ (I) und Z‐Olefine (V) wird hinsichtlich der Isomerenverteilung der gebildeten En‐Additionsprodukte (II)+(III)+(IV) (nachfolgende Reduktion zu denAlkoholen (VI) + (VII) + (VIII)) untersucht.

The question of the role of singlet oxygen in the dye-sensitised photo-oxygenation of α-oxo-carboxylic acids

The dye-sensitised photo-decarboxylation of α-oxo-carboxylic acids in the presence of oxygen has been studied by laser flash photolysis and by utilising solvent isotope effects and the results show, contrary to previous claims, that singlet oxygen does not play a significant role.

Photo-oxygenation of diphenyldiazomethane in the presence of phenyl trimethylsilyl ketone. Oxygen transfer from carbonyl oxide to the silyl ketone

Dye-sensitized photo-oxygenation of diphenyldiazomethane in the presence of phenyl trimethylsilyl ketone produced trimethylsilyl benzoate by reaction of a carbonyl oxide with the silyl ketone accompanied by 1,2-rearrangement of the trimethylsilyl group, together with benzophenone.

Intramolecular reaction of carbonyl oxide. Formation of a silyl ester in the photosensitized oxygenation of a silyl diazo compound

Dye-sensitized photo-oxygenation of trimethylsilylphenyldiazomethane produced phenyl trimethylsilyl ketone and trimethylsilyl benzoate; the latter may be formed from the silyl substituted carbonyl oxide via intramolecular reaction.

ChemInform Abstract: DYE‐SENSITIZED PHOTOOXYGENATION OF AZIRIDINES

Chemischer InformationsdienstVolume 9, Issue 6 Preparative Organic Chemistry ChemInform Abstract: DYE-SENSITIZED PHOTOOXYGENATION OF AZIRIDINES V. BHAT, Search for more papers by this authorM. V. GEORGE, Search for more papers by this author V. BHAT, Search for more papers by this authorM. V. GEORGE, Search for more papers by this author First published: February 7, 1978 https://doi.org/10.1002/chin.197806097Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume9, Issue6February 7, 1978 RelatedInformation

SINGLET-OXYGEN REACTIONS OF 1,4-CYCLOHEXADIENE. A SYNTHETIC APPROACH TO THE BENZENE-1,4-ENDOPEROXIDE

Abstract Dye-sensitized photooxygenation of 1,4-diphenyl-1,4-cyclohexadiene (1) at 0 °C followed by reduction with sodium bisulfite gave 1,4-diphenyl-7-hydroxy-5,6-dioxabicyclo[2.2.2]oct-2-ene (2). Mesylation of 2 followed by treatment with potassium t-butoxide yielded p-terphenyl, accompanied with the generation of singlet oxygen.

Oxidative dimerization of N b-methoxycarbonyltryptamines by dye-sensitized photooxygenation in formic acid. Synthesis of (±)-folicanthine and (±)-chimonanthine

Oxidative dimerization of N b-methoxycarbonyltryptamines by dye-sensitized photooxygenation in formic acid. Synthesis of (±)-folicanthine and (±)-chimonanthine

The photosensitized oxygenation of olefins with reactors of different types

A comparative kinetic investigation of the homogeneous and heterogeneous dye-sensitized photooxygenation of 2,3-dimethyl-2-butene and 2-methyl-2-butene in two photochemical reactors. namely in the anular reactor and in a cylindrical reactor of original design inside an elliptical mirror, is reported. The merits of these two laboratory photochemical reactors are discussed, with particular emphasis on their mass transfer performances in this gas—liquid and gas—liqui—solid reaction. Two types of régimes exist. dynamic and chemical, in which the reaction takes place, according to the experimental conditions. In the anular reactor the presence of a wide dynamic régime is a severe hindrance for an adequate chemical kinetic analysis. The cylindrical reactor with special features for speeding up the mass transfer rate is a considerable improvement, as shown by a higher precision of the kinetic constants calculated through a statistical approach. This cylindrical reactor was also used as a slurry phase reactor with methylene blue supported on silica gel as a photosensitizer. The singlet oxygen production and quenching rates on the heterogeneous photosensitizer were then computed.