A mild and efficient method for halogenation of 3,5-dimethyl pyrazoles by ultrasound irradiation using N-halosuccinimides - Stefani, Hélio Alexandre; Pereira, Claudio Martim Pereira de; Almeida, Roberta Bernardo de; Braga, Rodolpho de Campos; Guzen, Karla Pierdoná; Cella, Rodrigo (Tetrahedron Letters, 2005)