Studies towards the Taming of the ‘Carbocation’ in the Regioselective Ring Opening of Epoxides to Allylic Alcohols
作者:William Motherwell、Helen Chapman、Karim Herbal
DOI:10.1055/s-0029-1219373
日期:2010.3
Regioselective isomerisation of epoxides to allylic alcohols can be achieved using p-toluenesulfonic acid in the presence of 1,3-dimethylimidazolidin-2-one.
more photoresistant sensitizer for singlet-oxygen oxygenation of olefins than in the absence of the amines. This is ascribed to the facts that ZnTPP forms a 1 : 1 complex with DABCO, and that DABCO coodinated to ZnTPP has no ability to quench singlet oxygen, as revealed by detection of singlet oxygen phosphorescence and product distributions in oxygenation of d-limonene, 1,2-dimethylcyclohexene, and 1-phenylcyclobutene
Active Oxygen Species and Structure Specificity of Antipsoriatic Anthrones
作者:Klaus Müller
DOI:10.1002/ardp.19883210703
日期:——
Twenty‐one analogues of the antipsoriatic compound dithranol were tested for their capability to produce 1O2 and O2.‐. A correlation was found between the production of activeoxygenspecies and the minimum structure for the antipsoriatic activity of anthrone derivatives. The ability of the anthrones to sensitize the formation of 1O2 is a function of the deprotonated hydroxyl group at C‐1 associated
Synthetic Chemistry with Fullerenes. Photooxygenation of Olefins
作者:Hidetoshi Tokuyama、Eiichi Nakamura
DOI:10.1021/jo00084a036
日期:1994.3
Under irradiation with visible or UV (>290 nm) light in the presence of molecular oxygen and a minute amount of fullerenes, olefins and dienes undergo ene and Diels-Alder reactions with singlet oxygen to give photooxygenation products. The regio- and stereoselectivities of the photooxygenation of beta-myrcene, (+)-pulegone, 4-methylpent-3-en-2-ol, and (+)-limonene were very similar to those observed in known singlet oxygen reactions, indicating that the fullerene-sensitized reaction generates free singlet oxygen. The efficiency of fullerenes and conventional sensitizers was qualitatively examined by using the Diels-Alder reaction between O-1(2) and furan-2-carboxylic acid as a probe. Among those examined, C-70 was found to be the most effective. The reaction was the fastest and completed with as little as 0.0001 equiv of C-70. C-60 and hematoporphyrin were found to be of similar efficiency. The methanofullerene 13, which lacks one olefinic conjugation in the C-60 core, was as good as C60 itself, but the aminofullerene 14, lacking six double bonds, was quite inferior. The fullerene carboxylic acid 15, which was previously shown to show considerable biochemical activity, was found to be capable of generating singlet oxygen in aqueous DMSO.