Migration of an acyl group in the pyrazole system: synthesis of 1-acyl-3-hydroxy-1H-pyrazoles and related derivatives. A new preparation of N,N ′-diacylhydrazines
from 4-ethoxymethylene-2-phenyloxazol-5(4H)-one (1) and hydrazides, 4-phenylsemicarbazide, 4-phenylthiosemicarbazide and benzyl carbazate in boiling dioxane is described. The method includes a migration of an acyl or related unit. The X-ray study and NMR spectroscopic examination confirmed the structure of the products. A one-pot synthesis of N,N′-diacylhydrazines from hydrazides by the assistance of
Unsymmetrical ureas and S-thiocarbamates were prepared in good to excellent yields by direct condensation of phenylurea with amines and thiols in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) without the addition of any additives. The [BMIM]BF4 ionic liquid is a mild medium and can be recycled and reused several times.