An efficient preparation and the properties of 1,2-bis(3-guaiazulenylmethylium)benzene bishexafluorophosphate

Reaction of guaiazulene (1) with a 0.5 molar amount of phthalaldehyde in acetic acid in the presence of hexafluorophosphoric acid at 25°C for 2 h under aerobic conditions quantitatively gives the title new dicarbocation compound, 1,2-bis(3-guaiazulenylmethylium)benzene bishexafluorophosphate (3), which upon reduction with zinc powder in acetonitrile at 0°C under aerobic conditions rapidly affords a unique rearrangement product, 6,11-dimethyl-12-(3-guaiazulenyl)-9-isopropylnaphtho[2,3-a]azulene (5), as a major product.