Substrate-Controlled [5+1] Annulation of 5-Amino-1H-phenylpyrazoles with Alkenes: Divergent Synthesis of Multisubstituted 4,5-Dihydropyrazolo[1,5-a]quinazolines
A new and efficient [5+1] annulation reaction for the first synthesis of 5,5-disubstituted 4,5-dihydropyrazolo[1,5-a]quinazolines is described. This transition-metal-free tandem cyclization was performed with 5-amino-1H-phenylpyrazole and readily availabl
Iron-catalyzed direct sulfenylation and selenylations of phenylpyrazoles: Synthesis of fipronil derivatives with disulfides promoted by a catalytic amount of iodine
The direct thiolation of phenylpyrazole with disulfide using the FeBr 3/I2 complex as the catalyst in MeCN at 80 °C was reported. With the optimum conditions, several fipronil derivatives of 4-sulfenylpyrazole were synthesized by the reaction of 5-amino-1-[2,6-dichloro- 4-(trifluoromethyl)phenyl-lH-pyrazole-3-arbonitrile (1a) with disulfides (2) in moderate to good yields. The coupling reaction with diaryl diselane also occurred under similar conditions.
Xu, Mei,Zhang, Xiao Hong,Zhong, Ping
experimental part
p. 3472 - 3481
(2012/09/22)
Copper-catalyzed selective S-arylation of 1,2-bis(o-amino-1H-pyrazolyl) disulfides with arylboronic acids
Copper-catalyzed oxidative S-arylation of 1,2-bis(o-amino-1H-pyrazolyl) disulfides with arylboronic acids for the synthesis of (o-amino-1H-pyrazolyl) aryl sulfides has been developed in the presence of CuI, 1,10-phenanthroline, and O2. A variet