Investigations on the reactivity of arylboronic acid with phenolic pyrazole

Reaction of phenylboronic acid with phenolic pyrazole was carried out in 1:1 stochiometry using toluene as a solvent. Depending on the steric bulk of the group present on the pyrazole ring, PhB (HPhPzPh)(OEt) 1, [(PhB)(PhPzHt-Bu)(OH)][(PhB)2(PhPzt-Bu)2(O)] 2 and (PhBPhPz)2 3 were isolated. Compound 3 is an example of cis-isomer of pyrazabole crystallized in a boat conformation for the B2N4 heterocycle.