An efficient approach to isoindolo[2,1-b][2]benzazepines via intramolecular [4+2] cycloaddition of maleic anhydride to 4-α-furyl-4-N-benzylaminobut-1-enes |
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Authors: | Fedor I. Zubkov Ekaterina V. Boltukhina Alexey V. Varlamov |
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Affiliation: | a Organic Chemistry Department of Russian Peoples' Friendship University, 6, Miklukho-Maklayia St., Moscow 117198, Russian Federation b Center of Drugs Chemistry-All-Russian Institute for Chemical and Pharmaceutical Research, 7, Zubovskaya St., Moscow 119815, Russian Federation |
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Abstract: | Acylation of 4-α-furyl-4-N-benzylaminobut-1-enes with maleic anhydride gave 4-oxo-3-aza-10-oxatricyclo[5.2.1.01,5]dec-8-ene-6-carboxylic acid via amide formation followed by intramolecular Diels-Alder reaction of furan (IMDAF). The cycloaddition proceeded under mild reaction conditions (25 °C) and provided only the exo-adduct in quantitative yield. Treatment of this compound with PPA gave isoindolo[2,1-b][2]benzazepine derivatives via ring opening, aromatization and intramolecular electrophilic alkylation. In order to extend the scope of the reaction sequence, 7-oxo-5,11b,12,13-tetrahydro-7H-isoindolo[2,1-b][2]benzazepine-8-carboxylic acids were further transformed into useful synthetic intermediates. |
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Keywords: | Homoallylamines Isoindolobenz-2-azepines Intramolecular Diels-Alder reaction IMDAF Intramolecular electrophilic alkylation |
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