[DO NOT ALTER/DELETE THIS TEXT]Irradiation of substituted 2-benzylidenecyclopentanone O-alkyl and O-acetyloximes in methanol provides a convenient synthesis of alkyl, alkoxy, hydroxy, acetoxy, amino, dimethylamino and benzo substituted annulated quinolines. paraSubstituents yield 6-substituted-2,3-dihydro-1H-cyclopenta[b]quinolines with 8-substituted products being obtained from ortho-substituted starting materials. Reactions of meta-substituted precursors are highly regioselective, with alkyl substituents leading to 5-substituted 2,3-dihydro-1H-cyclopenta [b]quinolines and more strongly electron-donating substituents generally resulting in 7-substituted products. 2-Furylmethylene and 2-thienylmethylene analogues yield annulated furo-and thieno-[2,3e]pyridines respectively. Sequential E-to Z-benzylidene group isomerisation and six π-electron cyclisation steps result in formation of a short-lived dihydroquinoline intermediate which spontaneously aromatises by elimination of an alcohol or acetic acid. For 2-benzylidenecyclopentanone Oallyloxime, singlet excited states are involved in both steps.

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Fused pyridine derivatives R 0450Quinoline Synthesis: Scope and Regiochemistry of Photocyclization of Substituted Benzylidenecyclopentanone O-Alkyl and O-Acetyloximes. -The study of various oximes reveals that the nature of the leaving group does not affect the cyclization. The reactions of meta-substituted precursors are highly regioselective: alkyl substituents lead to 5-substituted products (XIV), whereas more strongly electron-donating substituents give 7-substituted derivatives. Substrates (Ic), (Id), and (XXIV) (cf. following scheme) do not react. Oximes bearing π-systems other than the benzylidene phenyl group also produce fused quinolines (to be continued). -(AUSTIN, M.; EGAN, O. J.; TULLY, R.; PRATT*, A. C.; Org. Biomol. Chem. 5 (2007) 23, 3778-3786; Sch. Chem. Sci., Dublin City Univ., Dublin 9, Ire.; Eng.) -Klein 15-148

Fused pyridine derivatives R 0450 Quinoline Synthesis: Scope and Regiochemistry of Photocyclization of Substituted Benzylidenecyclopentanone O-Alkyl and O-Acetyloximes. -(AUSTIN, M.; EGAN, O. J.; TULLY, R.; PRATT*, A. C.; Org. Biomol. Chem. 5 (2007) 23, p3778-p3786; Sch. Chem. Sci., Dublin City Univ., Dublin 9, Ire.; Eng.) -Klein 15-149