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Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
2,6-Dibromo-3,5-dimethylpyridine and 2,6-diiodo-3,5-dimethylpyridine
1Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, England. dpugh1@soton.ac.uk
Abstract:
The title compounds 2,6-dibromo-3,5-dimethylpyridine, C7H7Br2N, (I), and 2,6-diiodo-3,5-dimethylpyridine, C7H7I2N, (II), constitute the first structurally characterized examples of 2,6-dihalo-3,5-dimethylpyridines. Compound (I) crystallizes as a racemic twin with two symmetry-independent molecules in the asymmetric unit, while (II) is non-planar with the pyridine ring slightly deformed into a saddle shape, and exhibits crystallographically imposed twofold symmetry. Both (I) and (II) exhibit aromatic face-to-face pi-stacking in the solid state, although there are no other long-range interactions. In (I), alternate molecules are oriented at 90 degrees, resulting in X-shaped columns, while in (II), molecules pack in a parallel fashion, leading to a zigzag array.
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The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.

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