A Versatile Synthetic Method of 1-Alkylazulenes and Azulene by the Reactions of 3-Methoxycarbonyl-2<i>H</i>-cyclohepta[<i>b</i>]furan-2-one with<i>in situ</i>Generated Enamines
Methyl 3-alkylazulene-1-carboxylates were synthesized in high yields by the reaction of 3-methoxycarbonyl-2H-cyclohepta[b]furan-2-one with in situ generated morpholine enamines of aldehydes. Treatment of the esters with 100% phosphoric acid gave 1-alkylazulenes in excellent yields. Azulene was also synthesized in a good yield via methyl azulene-1-carboxylate with a modification of this method.
with sodium monobromoisocyanurate (SMBI) (1) to give 3‐bromo‐substituted azulenes 5 and 6, respectively. The brominations in dichloromethane gave the brominated products in low yields, while the reactions in dichloromethane–water gave the products in high yields. This indicates that SMBI (1) was hydrolyzed in the presence of water to generate hypobromic acid, which accelerated the bromination as a
Many derivatives of sodium alkylazulene sulfonates were newly synthesized and their antiulcer activites were examined in Shay pylorus-ligated rats. The values of lipophilicity (log P), a physicochemical parameter, of these new azulene derivatives were also examined in order to study the structure-activity relationship. The optimum value of log P which gave maximum anti-ulcer activity was about -1.0. Among the derivatives of azulene examined, 3-ethyl-7-isopropylazulene-1-sulfonic acid sodium salt (KT1-32) exhibited an extremely potent inhibitory action against Shay ulcer, and its antipeptic activity was more potent than than of guaiazulene sodium sulfonate (GAS). Furthermore, KT1-32 was extremely stable on heating as compared to GAS.