Reactions of azulenes with 1,2-diaryl-1,2-ethanediols in methanol in the presence of hydrochloric acid: comparative studies on products, crystal structures, and spectroscopic and electrochemical properties

Although reaction of guaiazulene () with 1,2-diphenyl-1,2-ethanediol () in methanol in the presence of hydrochloric acid at 60 °C for 3 h under aerobic conditions gives no product, reaction of with 1,2-bis(4-methoxyphenyl)-1,2-ethanediol () under the same reaction conditions as gives a new ethylene derivative, 2-(3-guaiazulenyl)-1,1-bis(4-methoxyphenyl)ethylene (), in 97% yield. Similarly, reaction of methyl azulene-1-carboxylate () with under the same reaction conditions as gives no product; however, reactions of 1-chloroazulene () and the parent azulene () with under the same reaction conditions as give 2-[3-(1-chloroazulenyl)]-1,1-bis(4-methoxyphenyl)ethylene () (81% yield) and 2-azulenyl-1,1-bis(4-methoxyphenyl)ethylene () (15% yield), respectively. Along with the above reactions, reactions of with 1,2-bis(4-hydroxyphenyl)-1,2-ethanediol () and 1-[4-(dimethylamino)phenyl]-2-phenyl-1,2-ethanediol () under the same reaction conditions as give 2-(3-guaiazulenyl)-1,1-bis(4-hydroxyphenyl)ethylene () (73% yield) and (Z)-2-[4-(dimethylamino)phenyl]-1-(3-guaiazulenyl)-1-phenylethylene () (17% yield), respectively. Comparative studies of the above reaction products and their yields, crystal structures, spectroscopic and electrochemical properties are reported and, further, a plausible reaction pathway for the formation of the products is described.