Highly selective mono-substitution in Pd-catalyzed cross-coupling reactions of 3,6-dichloropyridazine with organozinc compounds

Interrelation between long‐term viscoelasticity and viscoplastic responses of semicrystalline polymers

“…Unfortunately, the use of [Pd(PPh 3 ) 2 Cl 2 ] as catalyst (Table 1, entry 2) instead of [Pd(PPh 3 ) 4 ] did not solve the problem and afforded target dipyridazines 2 a , 2 b , and 2 c in modest yields (trace, 21 % and 23 %, respectively). Consequently, according to a modified Kasatkin procedure,19 the Negishi methodology was favored to perform the hetero‐cross‐coupling reaction of halogenopyridazine 13 with appropriate pyridyl zinc reagents 12 a – c 20 (Table 1, entry 3). The latter were prepared from the corresponding bromopyridines17b by treatment with 1.6 equiv of n ‐butyllithium in THF at −78 °C for 30 min prior to the addition of zinc dichloride (1.6 equiv).…”

1-Amino-4-benzylphthalazines as Orally Bioavailable Smoothened Antagonists with Antitumor Activity

“…These were then coupled via palladium catalysis with a variety of benzylzinc reagents to provide analogues 32-39. 21 Chlorophthalazines 39a,b were converted to the corresponding cyano derivatives 40a,b under palladium catalysis using Zn(CN) 2 . 22 Similar chemistry was used to explore modifications to region B (Scheme 3).…”

Synthesis of Aryl(di)azinylmethanes and Bis(di)azinylmethanes via Transition-Metal-Catalyzed Cross-Coupling Reactions

“…In 2005, Kasatkin and co-workers noticed that 3,6-dichloropyridazines can react selectively with alkyl-, alkynyl-, aryl-and benzylzinc species to give the corresponding monosubstituted products. 12 When 3,6-dichloropyridazine (25) was allowed to react with 1.6 equivalents of benzylzinc bromide (23a) or (3-chlorobenzyl)zinc chloride (24a) in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium, the resulting 6benzyl-3-chloropyridazines 26a,b were obtained selectively in moderate to good yields (Scheme 5).…”