Cyanonaphthalene derivative

The photoreactions of mono- and di-cyanonaphthalene derivatives with al-lyltrimethylsilane have been reported by Mizuno and Albini, independently [136,428,433,436], The product ratios of photocycloadducts via exciplexes and the allylated products via electron transfer were dependent on the solvent polarity and additives. The intramolecular photocycloaddition of the reductive allylated products efficiently gives tricyclic compounds in high yields [428,433,436] (Scheme 23). 

Due to their reduced aromatic character, naphthalene derivatives more easily undergo [2 + 2] photocydoaddition to give access to cyclobutane derivatives [49]. In some cases, the formal [4 + 2] addition is competitive. In contrast to the ground-state Diels-Alder reaction, the [4 + 2] products from these photochemical reactions result from a multistep reaction. Upon irradiation, the 1-cyanonaphthalene derivative 45... 

Due to their reduced aromatic character, naphthalene derivatives also frequently undergo ortho cycloaddition with alkenes (Sch. 4). 1-Cyano-naphthalene 13 reacts with cyclohexadiene to yield the regioisomeric ortho adducts 14 and 15 in good yields [34]. Two regioisomers 17 and 18 were also obtained from the intramolecular reaction of the 1-cyanonaphthalene derivative 16 [35]. The proportion of the two isomers depends on the solvent polarity. 

Maeda H, Mukae H, Mizuno K (2005) Enhanced efficiency and regioselectivity of intramolecular (2tc-i-27c) photocycloaddition of 1-cyanonaphthalene derivative using micrraeactors. Chem Lett 34 66-67... 

H. Maeda, H. Mukae, K. Mizuno, Enhanced efficiency and regioselectivity of intermolecular (2ti + 2ti) photocycloaddition of 1-cyanonaphthalene derivatives using microreactors, Chem. Lett. 2005, 34, 66-67. 

Intramolecular [2 + 2] photocycloaddition of 1-cyanonaphthalene derivatives in microflow reactors made of poly(dimethylsiloxane) (PDMS) has been developed. Both the efficiency and regioselectivity increased compared with those under batch conditions (Table 5.5) [16]. A glass-made microflow reactor is also effective for intramolecular photocydoaddition [17]. The effidency and regioselectivity have been further improved. 

Mizuno and coworkers [4] reported an enhancement in reaction efficiency, as well as regioselectivity, by conducting the photocycloaddition of a naphthalene derivative (1) (Scheme 6.1) in a microreactor. The authors found that in batch, irradiation of cyanonaphthalene derivative (1), using a filtered xenon lamp (A > 290 nm), afforded photocydoadducts (2) and (3) in 56% and 17% yield, respectively. In comparison, when conducting the reaction in a microreactor, employing an irradiation time of just 3.4 min, the desired compound (2) was obtained in an increased yield of 59%, while by-product (3) was reduced to 9%. 

Accordingly, Gassman and co-workers have shown that cyclic bicyclobutane derivatives can be activated by photoexcited 1-cyanonaphthalene, eq. 40 (115) ... 

The photocycloaddition of furan derivatives to 2-cyanonaphthalene (2-CN) affords caged products, which was first reported by Pac et al. [100-105], The product ratio in the photoreaction of 2-CN with 2-methylfuran is almost 1 1. 

Gilbert and his co-workers reported that the photocycloaddition of 1-cyanonaphthalenes (260 and 262) gave 261 and 263, independently [288] (Scheme 72). In addition, they prepared and photoirradiated a variety of compounds that connected naphthalene and alkenes by methylene, ether, and ester tethers at various lengths [289], Among them, the reaction of 264 gave the best result, whereas the 2-substituted derivative (265) did not give any product. 

The electron-transfer-induced chemistry of bicyclobutane systems offer a rich variety of reactions. Irradiation of naphthalene in the presence of 46 resulted in rapid fluorescence quenching without rearrangement. In contrast, irradiation with either 1-cyanonaphthalene or 9,10-dicyanoanthracene in solutions containing derivatives of 46 resulted in product formation. The product distribution obtained under electron-transfer conditions is compatible with radical cations of structure type 46 +, which is firmly established by ESR and CIDNP results. Nucleophilic capture of the 1,2,2-trimethyl derivative, 50", led to cleavage of the transannular bond. The initial eapture is followed by net addition, producing 51, or dehydrogenation, yielding 52 [179]. 

Irradiation of the benzoazanorbornadiene (69) does not follow the conventional route for such photochemically active systems. The reaction, affords 1-chloronaphthalene, by deamination, as well as two thermally labile indole derivatives (70, 71) by the route shown in Scheme 5. These are formed by 1,3-nitrogen migrations within the azanorbornadiene. A detailed study of the rearrangement of the cyclopropanonaphthalene (72) has identified the products shown in Scheme 6. The reaction is solvent dependent and is more rapid in non polar solvents, such as benzene, than in polar solvents. The isomeric cyclopropanonaphthalene (73), a product of the rearrangement shown in Scheme 6, yields 1-cyanonaphthalene as the principal product on irradiation. ... 

The behaviour of the cation radicals derived from bicyclobutane systems has been under intensive study by Gassman and his coworkers. Currently they have observed that the substituted derivative (185) photorearranges in good yield, using 1-cyanonaphthalene as the electron acceptor, to the isomer (186). Although this product can be synthesized independently by the photocyclization of the diene (187) the authors argue that this route is not in operation. The formation of the product (186) follows the one electron transfer path with subsequent rearrangement within the radical cation (188). ... 

The 1,2-photocycloaddition of acrylonitrile to naphthols or their methyl or trimethylsilyl ethers produces cyclobutane adducts e,g., 45), and these can be cleaved with base. This provides a synthetic route to (1- or 2-cyanoethyl)-substituted derivatives of the original naphthol. 1-Cyanonaphthalene (46) gives both 1,2-cycloadducts to the ring and a C N cycloadduct on irradiation with 1,2-dimethylcyclopentene, and the two reactions proceed by way of different singlet excited states of the aromatic nitrile. The photophysics of this system has been studied previously, but this is the first report in which the photoproducts are characterized. An intramolecular version of the reaction starting with the substituted 1-cyanonaphthalene (47) gives two 1,2-cycloadducts, the major one... 

Diastereomer-differentiating intramolecular [2+2] photocycloaddition has been reported for the diastereomeric 2,6-dienones (105) and (106). Both direct and sensitised irradiation of (105) yields (107) whereas (108) is formed from (106). Reinvestigation, at -78 °C, of the photocycloadditions of 1-cyanonaphthalene (1-CN) and 2-cyanonaphthalene (2-CN) with 1,3-cyclohexadiene has suggested that the primary major singlet-derived products are the corresponding exo-[4+4]adducts, (109) and (110) respectively, and the s>>/i-[2+2]adducts, (111) and (112) respectively. Consideration of primary and secondary orbital interactions has been used to interpret these observations. ... 

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