18436-05-0Relevant articles and documents
Stoichiometrically Sensitized Decarboxylation Occurring in a Molecular Crystal Composed of Phenanthridine and 3-Indoleacetic Acid
Koshima, Hideko,Ding, Kuiling,Matsuura, Teruo
, p. 2053 - 2054 (1994)
Irradiation of a molecular crystal between phenanthridine and 3-indoleacetic acid at -70 deg C causes decarboxylation to give 3-methylindole in high yield as the sole product; phenanthridine behaves like a stoichiometric sensitizer in the crystal.
Stoichiometrically sensitized decarboxylation occurring in the two-component molecular crystals of aza aromatic compounds and aralkyl carboxylic acids
Koshima, Hideko,Ding, Kuiling,Chisaka, Yosuke,Matsuura, Teruo,Miyahara, Ikuko,Hirotsu, Ken
, p. 10317 - 10324 (2007/10/03)
Highly selective photodecarboxylation could be achieved by utilizing a series of two-component molecular crystals of aralkyl carboxylic acids 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 quantitative yields, due to a smaller thermal motion of the radical species in the crystal lattice. Upon irradiating a crystal, a carboxylate radical and hydroacridine or hydrophenanthridine radical are produced via electron transfer from the acid to 1 or 2 and subsequent proton transfer followed by decarboxylation. Next hydrogen abstraction by an active aralkyl radical occurs in highest priority over the shortest distance of 3.2-3.5 A? resulting in the formation of a corresponding decarboxylated product and the regeneration of 1 or 2. Occurrence of radical coupling is low due to the longer coupling distance of 4.5-6.5 A? estimated from the crystallographic data of the starting two-component molecular crystals. The hydrogen abstraction path in the crystal lattice could be confirmed by the reaction of a deuterated crystal 1 · bD in which the CO2H group was replaced by CO2D, giving a deuterated 1-methyl(CH2D)naphthalene as a product. Regeneration of 1 or 2 means that the acceptor plays the role of a stoichiometrical sensitizer, which can act in only one cycle, retaining the initial crystal structure. Such a stoichiometrical sensitization is a novel photochemical process, which occurs specifically in the solid state.
