Pseudoesters and derivatives. XXV. 1,3-Dipolar cycloaddition of diazomethane to 5-methoxy-3-pyrrolin-2-ones |
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Authors: | Francisco Fari a,M. Victoria Martí n,M. Carmen Paredes,Amelia Tito |
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Affiliation: | Francisco Fariña,M. Victoria Martín,M. Carmen Paredes,Amelia Tito |
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Abstract: | Cycloaddition of diazomethane to pyrrolinones 1a,b,d,e affords only one regioisomer as a mixture of the epimeric pyrrolopyrazolines 2 and 2 ′,4-Halo derivatives 1f,g react with diazomethane to give the two possible regioisomers 2 and 3. The regio- and stereochemistry of the adducts is evidenced by the 1H-nmr data. The primary adducts originated from the halopyrrolinones suffer dehydrohalogenation to give aromatized products, which by further methylation give derivatives of type 7, 8, 10 and 11. |
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