Photoinitiated Domino Reactions:N-(Adamantyl)phthalimides andN-(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.

Triple photochemical domino reaction of a tetrafluorostilbene terminating in double fluorine atom transfer

“…Using F 4 -stilbene 1, we performed a photoinduced domino reaction consisting of three photochemical steps: oxidative photocyclisation/photoinduced Diels-Alder reaction/photoinduced double group transfer reaction. Multiple photochemical domino reactions remain undeveloped [43][44][45] because domino reactions initiated by photoirradiation conventionally consist of consecutive thermal steps after the first photochemical step. One advantage of a photochemical domino process over a thermal one is that the domino process can be suspended and restarted at will simply by controlling the irradiation time.…”

Photoinduced Cyclization Reactions in Aqueous Media

“…It represents the first example of the 2-azahexacyclo[8.7.1.11,4.04,9.011,16.012,18] nonadeca-4,6,8-triene skeleton [18,19]. It represents the first example of the 2-azahexacyclo[8.7.1.11,4.04,9.011,16.012,18] nonadeca-4,6,8-triene skeleton [18,19].…”

“…It represents the first example of the 2-azahexacyclo[8.7.1.11,4.04,9.011,16.012,18] nonadeca-4,6,8-triene skeleton [18,19]. Photochemical transformation of 29 into 30 does not take place in nonpolar solvents such as cyclohexane and occurs very inefficiently in MeCN ( 10-4) [19]. Photochemical transformation of 29 into 30 does not take place in nonpolar solvents such as cyclohexane and occurs very inefficiently in MeCN ( 10-4) [19].…”

Photoinduced homolytic C–H activation inN-(4-homoadamantyl)phthalimide

“…In continuation of our interest in the Majerski's laboratory in the functionalization and transformation of cage molecules [38–48] as well as the preparation of biologically active compounds [49], we turned our attention to adamantylphthalimides [50–52]. Recently, in cooperation with the group of Griesbeck we discovered a photoinduced domino reaction of adamantylphthalimide that involves two consecutive γ H-abstractions and leads to a complex methanoadamantane benzazepinone 2 (Scheme 1) [51].…”

“…Recently, in cooperation with the group of Griesbeck we discovered a photoinduced domino reaction of adamantylphthalimide that involves two consecutive γ H-abstractions and leads to a complex methanoadamantane benzazepinone 2 (Scheme 1) [51]. The mechanism of the photoinduced domino reaction was investigated and it was found that it probably takes place from a higher excited triplet state or the singlet state [52]. Herein, we report the synthesis and photochemistry of a phthalimide derivative of homoadamantane 5 .…”