title: Photoinitiated domino reactions: N-(adamantyl)phthalimides and N-(adamantylalkyl)phthalimides.
abstract: Phthalimides 1-6 undergo photochemical reactions upon direct irradiation as well as triplet sensitization and give rise to new products. Besides formation of the primary photoproducts, the first photochemical step initiates a subsequent thermal domino reaction or a domino sequence of a thermal and a photochemical reaction. The latter, involving two photochemical intramolecular gamma-H abstractions, was observed with phthalimides 1, 3, and 6 and delivered stereospecifically the hexacyclic benzazepine products 12, 19, and 27, respectively. The lowest triplet states of 1-6 were characterized in several solvents upon direct and acetone-sensitized excitation. The intermolecular electron transfer from triethylamine and DABCO was studied, and the radical anions were observed. Electrochemical measurements showed that intramolecular electron transfer from the adamantyl group of 1-6 to the lowest triplet state of the phthalimides is not feasible. The formation of products can be explained by intramolecular H-abstraction from the (alkyl)adamantane to the excited phthalimide, either from the excited singlet state or a hidden upper excited triplet state.
authors.affiliation: Department of Organic Chemistry and Biochemistry, Ruder Bosković Institute, Bijenicka cesta 54, 10 000 Zagreb, Croatia.
authors.forename: Margareta
authors.initials: M
authors.lastname: Horvat
authors.forename: Helmut
authors.initials: H
authors.lastname: Görner
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Warzecha
authors.forename: Jörg
authors.initials: J
authors.lastname: Neudörfl
authors.forename: Axel G
authors.initials: AG
authors.lastname: Griesbeck
authors.forename: Kata
authors.initials: K
authors.lastname: Mlinarić-Majerski
authors.forename: Nikola
authors.initials: N
authors.lastname: Basarić
mesh_terms: D004563:Electrochemistry; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010777:Photochemistry; D010797:Phthalimides / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: D010797:Phthalimides