Reactions of guaiazulene with 2-furaldehyde, thiophene-2-carbaldehyde and pyrrole-2-carbaldehyde in methanol in the presence of hexafluorophosphoric acid: comparative studies on molecular structures and spectroscopic, chemical and electrochemical properti

Reactions of guaiazulene () with heteroaromatic-carbaldehydes [i.e., 2-furaldehyde (), thiophene-2-carbaldehyde () and pyrrole-2-carbaldehyde ()] in methanol in the presence of hexafluorophosphoric acid at 25 °C for 30 min under aerobic conditions give (2-furyl)(3-guaiazulenyl)methylium hexafluorophosphate (), (3-guaiazulenyl)(2-thienyl)methylium hexafluorophosphate () and (3-guaiazulenyl)(2-pyrrolyl)methylium hexafluorophosphate (), respectively, in 93, 98 and 85% yields. Comparative studies on the molecular structures as well as the spectroscopic, chemical and electrochemical properties of the methylium hexafluorophosphates stabilized by 3-guaiazulenyl and 2-furyl (or 2-thienyl or 2-pyrrolyl) groups are reported.