Short Access to Belt Compounds with Spatially Close CC Bonds and Their Transannular Reactions |
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| Authors: | Prof?Dr Pelayo Camps Dr Tània Gómez Ane Otermin Dr Mercè Font‐Bardia Dr Carolina Estarellas Prof?Dr Francisco Javier Luque |
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| Institution: | 1. Laboratori de Química Farmacèutica (Unitat Associada al CSIC), Facultat de Farmàcia and Institut de Biomedicina (IBUB), Universitat de Barcelona, Av. Joan XXIII 27–31, 08028 Barcelona (Spain);2. Departament de Cristallografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona, Martí Franquès s/n. 08028 Barcelona (Spain) and Unitat de Difracció de RX, Centres Científics i Tecnològics de la Universitat de Barcelona (CCiTUB), Solé i Sabarís 1–3, 08028 Barcelona (Spain);3. Departament de Fisicoquímica, Facultat de Farmàcia and Institut de Biomedicina (IBUB), Universitat de Barcelona, Prat de la Riba 171, 08921 Santa Coloma de Gramenet (Spain) |
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| Abstract: | Two domino Diels–Alder adducts were obtained from 3,7‐bis(cyclopenta‐2,4‐dien‐1‐ylidene)‐cis‐bicyclo3.3.0]octane and dimethyl acetylenedicarboxylate or N‐methylmaleimide under microwave irradiation. From the first adduct, a C20H24 diene with C2v symmetry was obtained by Zn/AcOH reduction, hydrolysis, oxidative decarboxylation, and selective hydrogenation. Photochemical 2+2] cycloaddition of this diene gave a thermally unstable cyclobutane derivative, which reverts to the diene. However, both the diene and the cyclobutane derivatives could be identified by X‐ray diffraction analysis upon irradiation of the diene crystal. New six‐membered rings are formed upon the transannular addition of bromine or iodine to the diene. The N‐type selectivity of the addition was examined by theoretical calculations, which revealed the distinct susceptibility of the doubly bonded carbon atoms to the bromine attack. |
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| Keywords: | density functional calculations domino reactions photochemistry polycycles X‐ray diffraction |
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