Stereoselective preparation of methylenecyclobutane-fused angular tetracyclic spiroindolines via photosensitized intramolecular [2+2] cycloaddition with allene |
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Authors: | Noriyoshi Arai Takeshi Ohkuma |
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Institution: | 1. Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan;2. Frontier Chemistry Center, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan |
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Abstract: | Irradiation of 3-(hexa-4,5-dienyl)indole derivatives in the presence of 3′,4′-dimethoxyacetophenone by a high-pressure mercury lamp through Pyrex glass gave the corresponding 2+2] cycloaddition products stereoselectively in high yields. The major product was a methylenecyclobutane-fused angular tetracyclic spiroindoline derivative produced by the 2+2] cycloaddition through a parallel orientation. The minor product was a hexahydromethanocarbazole derivative through a crossed orientation. Electron-withdrawing substituents, such as acyl or alkoxycarbonyl, on the indole nitrogen were suitable for this reaction. |
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Keywords: | Corresponding authors at: Division of Applied Chemistry Faculty of Engineering Hokkaido University Sapporo Hokkaido 060-8628 Japan (N Arai and T Ohkuma) Indole Allene Photoreaction [2+2] Cycloaddition |
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