Syntheses of heterocyclic compounds. Part XVIII. Aminolysis of 3-aryl-4-bromosydnones, and acid hydrolysis of 3-arylsydnoneimines
作者:G. S. Puranik、H. Suschitzky
DOI:10.1039/j39670001006
日期:——
various 3-aryl- and 3-heteroaryl-4-bromosydnones with piperidine gives the corresponding piperidino-glycyl-piperidines. Fluorine labelling has confirmed the postulated course of fission induced by acids in 3-aryl-sydnoneimines.
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
A convenient and transition-metal-free synthesis of 1-arylpyrazoles that involves the cycloaddition of 3-arylsydnones and acrylic acid is presented. The process proceeds smoothly to obtain the target products with moderate to high yields.