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Microwave-assisted regioselective synthesis of substituted-9-bromo-9,10-dihydro-9,10-ethanoanthracenes via Diels-Alder cycloaddition
oleh: Mujeeb A. Sultan, Mansour S.A. Galil, Mohyeddine Al-Qubati, Abdullah Mohammed Al-Majid, Assem Barakat
Format: | Article |
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Diterbitkan: | Elsevier 2020-12-01 |
Deskripsi
The substituted-9-bromo-9,10-dihydro-9,10-ethanoanthracenes ortho 8a-12a and meta 8b-13b have been synthesized via Diels-Alder reaction under microwave conditions. The cycloadduct isomers ortho 8a-11a and meta 8b-11b, with priority to ortho 8a-11a, were obtained from the reaction of 9-bromoanthracene 1 with acrylonitrile 2, 2-chloroacrylonitrile 3, methacryloyl chloride 4 and acrylic acid 5, while ortho 12a and meta 12b, with priority to meta 12b, was obtained from the reaction of 9-bromoanthracene 1 with 1-cynao vinyl acetate 6. Interestingly, the only isomer meta 13b was obtained from the reaction of 9-bromoanthracene 1 with phenyl vinyl sulfone 7. The results proved that the steric or/and electronic nature of the dienophile substituent is/are playing significant roles in the regioselectivity and isomers ratio.