Microphotochemistry: 4,4'-Dimethoxybenzophenone mediated photodecarboxylation reactions involving phthalimides

• Oksana Shvydkiv,
• Kieran Nolan and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2011, 7, 1055–1063, doi:10.3762/bjoc.7.121

• application of LEDs [37]. We have therefore investigated the usage of 4,4’-dimethoxybenzophenone (DMBP) as a photocatalyst that absorbs readily in the UVA region. In this publication we present preliminary results of five DMBP mediated model transformations (Scheme 1). All reactions were previously studied

Synthesis of rigidified flavin–guanidinium ion conjugates and investigation of their photocatalytic properties

• Harald Schmaderer,
• Mouchumi Bhuyan and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 26, doi:10.3762/bjoc.5.26

• larger (Table 1, entries 1+2) in comparison to the ammonium salt 8 (entry 3). In water, however, the accelerating effect is not observed (entries 5–8). The presence of the photocatalyst is essential in all cases, as the non-catalyzed hydrolysis is slow under the reaction conditions (<5% conversion). In

• with blue light the yield after 8 h reaction time increased further (entry 2) and was significantly higher as in the absence of a photocatalyst (entry 5). However, a comparison with tetraacetyl riboflavin (3) under identical reaction conditions showed an even more pronounced acceleration of the

Green oxidations: Titanium dioxide induced tandem oxidation coupling reactions

• Vineet Jeena and
• Ross S. Robinson

Beilstein J. Org. Chem. 2009, 5, No. 24, doi:10.3762/bjoc.5.24

• photocatalyst with a band gap of 3.2 eV corresponding to a wavelength of 387 nm [14]. Thus, we attempted to evaluate titanium dioxide as a potential TOP type catalyst based on the excellent work of Taylor and co-workers [15][16] by examining its behaviour under various energy sources (Table 1). Titanium dioxide

Photosonochemical catalytic ring opening of α-epoxyketones

• Hamid R. Memarian and
• Ali Saffar-Teluri

Beilstein J. Org. Chem. 2007, 3, No. 2, doi:10.1186/1860-5397-3-2

• -2,4,6-triphenylpyridinium tetrafluoroborate (NBTPT) as photocatalyst in methanol. Sonication of these compounds in the presence of NBTPT did not result in the opening of epoxide ring, but the use of ultrasound increased the rate of photoreaction. Background The advantages of ultrasound-assisted

• the corresponding γ-lactone. [19] In our recent study, we have used 1-benzyl-2,4,6-triphenylpyridinium tetrafluoroborate (NBTPT) as photocatalyst in a highly diastereoselective ring opening of α-epoxyketones in acetone solution with the formation of 1.3-dioxolanes. [20] Ring opening of epoxides and α

• carbonyl compounds [43][44][45][46][47][48][49][50] or by nucleophilic attack of appropriate reagents. [36][39][51] Recently, we have reported on the photocatalytic ring opening of α-epoxyketones 1a-f and 2,4,6-triphenylpyrilium tetrafluoroborate (TPT) as photocatalyst in methanol, [37] cyclohexanone, [38