Variation in site of lithiation with ring substituent of N ′-aryl-N,N-dimethylureas: application in synthesis
作者:Keith Smith、Gamal A. El-Hiti、Amba P. Shukla
DOI:10.1039/a903464a
日期:——
reagent of N′-(4-chlorophenyl)-N,N-dimethylurea with 2-chlorocyclohexanone gives an 82% isolated yield of 4a-hydroxy-N-(dimethylaminocarbonyl)-1,2,3,4,4a,9a-hexahydrocarbazole, which on treatment with trifluoroacetic acid affords N-(dimethylaminocarbonyl)-1,2,3,4-tetrahydrocarbazole in 97% yield. Double lithiation of N′-phenyl- and N′-(4-methylphenyl)-N,N-dimethylureas is achieved using tert-butyllithium