Synthesis and Crystal Structure of C₁-Symmetric 3,3′-Bi(1,1′-dinaphthyl-camphopyrazole)

Abstract

The compound 3,3 -bi(1,1 -dinaphthyl-camphopyrazole) 1, C 42 H 42 O 4 , was obtained in good yield and structurally characterized by 1 H and 13 C NMR spectroscopy, elemental analysis, and X-ray diffraction. It consists of a 3,3 -bipyrazole group with each pyrazole ring containing a fused camphor group and a naphthalene ring bonded to the adjacent nitrogen atom in the ring. Both of the trimethyl, 5-membered rings of the fused camphor group form an envelope with the apex carbon atom as the flap in each case. In the crystal, weak -stacking interactions are observed between nearby 6-carbon rings of the two naphthalene rings linking the molecules into extended chains. Weak -ring intermolecular interactions are also observed between naphthalene atoms and pyrazole rings from each of the groups helping to stabilize the crystal packing. No classical hydrogen interactions are formed.

Synthetic Routes to Bioactive Bipyrazole Derivatives

“…Nitration of the aminated 3,3′‐bipyrazole 77 with nitronium tetrafluoroborate (NO 2 BF 4 ) in the presence of potassium acetate resulted in the formation of monopotassium salt 81 . The potassium salt 81 was found to have applications in the field of primary explosives [64] …”

“…[63] The The potassium salt 81 was found to have applications in the field of primary explosives. [64] A one-pot three-component synthesis of the 3,3'-bipyrazole derivatives 84 was regioselectively synthesized in 80-88 % yields by reaction of a aroylideneketene dithioacetals 82, Bestmann Ohira reagent 83 and hydrazine hydrate using KOH as base in methanol solvent (Scheme 17). The reaction sequence proceeded through 5 steps: 1,3-dipolar cycloaddition, protonation, air oxidation, pyrazole formation and demethylation, respectively.…”