Synthesis of pyrrolo[2,1‐a]phthalazines by 1,3‐dipolar cycloaddition of phthalazinium N‐ylides with alkenes in the presence of tetrakis‐pyridine cobalt (II) dichromate |
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Authors: | Jian Zhou Yuefei Hu Hongwen Hu |
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Abstract: | We describe here, for the first time, that 1‐cyano‐3‐benzoyl‐1,2,3,10b‐tetrahydropyrrolo2,1‐a]phthalazine (8), prepared by 1,3‐dipolar cycloaddition of 2‐phenacyl phthalazinium bromide ( 6a ) with acrylonitrile ( 7a ), can be aromatized by tetrakis‐pyridine cobalt (II) dichromate (TPCD) to give 1‐cyano‐3‐benzoylpyrrolo2,1‐α]phthalazine ( 9a ) in good yield. Furthermore, a general and convenient one‐pot procedure for preparation of pyrrolo2,1‐α]phthalazines ( 9a‐p ) was developed by 1,3‐dipolar cycloaddition of phthala zinium N‐ylides ( 6a‐c ) with alkenes ( 7a‐g ) in the presence of TPCD. |
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