3(5)-(1-Adamantyl)pyrazoles: chemistry and molecular structure

Abstract

The synthesis and molecular structure of 3(5)-(1-adamantyl)-4-bromopyrazole (2) are reported. The compound crystallizes in tetramers formed by units of the 5-adamantyl tautomer 2b, linked by N–H⋯N hydrogen bonds. The results are discussed in the light of other tetramers found in N-unsubstituted pyrazoles. The comparison between ¹³C and ¹⁵N in the solid state, CPMAS, and solution NMR spectra shows that tautomer 2b is also dominant in solution. Nitration of 3(5)-(1-adamantyl)pyrazole occurs at position 4 of the pyrazole ring but it is accompanied of oxidation of the adamantyl substituent at position 3′.