Photodecarboxylation of unmodified carboxylic acids with use of aza aromatic compounds
作者:Keiji Okada、Katsura Okubo、Masaji Oda
DOI:10.1016/s0040-4039(00)70663-0
日期:——
A very simple procedure for photodecarboxylation of intact carboxylicacids leading to alkanes is developed with use of aza aromatic compounds as light absorbers and t-BuSH as a hydrogen donor.
crystals of aralkyl carboxylicacids such as 3-indolepropionic acid (a) and 1-naphthylacetic acid (b) combined with acridine (1) or phenanthridine (2) as an electron acceptor. The 1:1 hydrogen bonded crystals were prepared by recrystallization from the solutions. Irradiation of the crystals at −70 °C caused highly selective decarboxylation to give corresponding decarboxylated compounds alone in nearly
Photochemical Reductive Acylation and Oxidative Acyl Activation on Phenazine and Related Nitrogen Heterocycles
作者:Makoto Takagi、Setsuo Goto、Tsutomu Matsuda
DOI:10.1246/bcsj.53.1777
日期:1980.6
Irradiation of phenazine in acetaldehyde or propionaldehyde solution gave an N-acylated 5,10-dihydrophenazine. Acridine similarly gave 9-acyl-9,10-dihydroacridine, and 10-methylacridinium salt gave 9-acyl-10-methyl-9,10-dihydroacridine. In methanol N-acylated dihydro-phenazines reacted with N-bromosuccinimide to give phenazine and methyl car boxy lates in quantitative yield.
two-component molecular crystals of 2-thienylacetic acid (1) or bis(2-thienyl)acetic acid (2) with azaaromatic compounds such as acridine (a) and phenanthridine (b) were prepared by crystallization from the solutions of both components. Irradiation of the crystals caused photodecarboxylation and radical intermediates which give decarboxylated and condensation products. The relationship between the crystal
A yellow crystal 3 and a red crystal 4 simultaneously crystallize from a solution of acridine 1 and phenothiazine 2 in acetonitrile. Similar N · · · H–N hydrogen bonding pairs of 1 and 2 are formed in the two crystals. The 3∶4 crystal 3 has a slightly uncommon molecular arrangement of which four acridine molecules out of twelve are disordered in the unit cell. The 1∶1 crystal 4 has a more rigid packing of the hydrogen bonding pairs. Irradiation of 3 gives a photoadduct 5 as the sole product, whereas 4 shows almost no photoreactivity. The occurrence of photoinduced electron transfer has been confirmed by the measurement of transient absorption spectra of the crystals 3 and 4. However, the two-stage decay of the transient absorption of 3 with lifetimes of 2 and 50 ps is different from that of 4 with a single short lifetime of 2 ps. Upon irradiating 3, electron transfer, proton transfer and subsequent radical coupling occur over the shortest distance of 4.1 Å between the preradical carbon and nitrogen atoms in the crystal lattice followed by dehydrogenation to afford the product 5. In the case of the red crystal 4, the radical coupling is difficult because of the longer coupling distance of 5.6 Å and the more restricted movement in the rigid crystal lattice. The results indicate that the observed photochemical behaviour of 3 and 4 are controlled by the molecular arrangement in the crystal lattice.