Syntheses of heterocyclic compounds. Part XII. Halogen-substituted 3-arylsydnones
作者:M. Bellas、H. Suschitzky
DOI:10.1039/j39660000189
日期:——
The reactivity of halogen in the benzene ring and also in the 4-position of the sydnone ring of various arylsydnones towards nucleophiles has been investigated. The course of ring-fission in 4-halogenosydnones induced by primary amines differs from that of secondary amines. The reaction in the latter case provides a preparative route to diamino-acid amides. Several new halogenosydnones are described
of 4-trifluoromethyl pyrazoles have been prepared via the copper-catalyzed cycloaddition of 2-bromo-3,3,3-trifluoropropene with a variety of N-arylsydnone derivatives under mild conditions. This new protocol under optimized reaction conditions [Cu(OTf)2/phen, DBU, CH3CN, 35 °C] afforded 4-trifluoromethyl pyrazoles in moderate to excellent yields with excellent regioselectivity.
and general method for the synthesis of 3-trifluoromethyl-4‑trifluoroacetyl pyrazoles from the cycloaddition of sydnones with 1,1,1,5,5,5-hexafluoropentane-2,4-dione has been established. Using ZnI2/bpy as a catalyst in THF, this protocol proved to be general to prepare a variety of 3-trifluoromethyl-4‑trifluoroacetyl pyrazoles in good yields. Utility of this method was demonstrated by further transformations