ANTIULCER AGENT

NEW MATERIAL:A compound of formula I (R1 is H or 1-4C lower alkyl) and a salt thereof. EXAMPLE:The compound of formula II. USE:A chemically stable antiulcer agent, having excellent selectivity, with little side effects, and useful for diseases, e.g. duodenal ulcer, and administrable orally and parenterally. PROCESS:As shown in the reaction formulas, a cyclohexene derivative of formula III is subjected to the oxidative ring cleavage to give a dialdehyde derivative of formula IV, which is then subjected to the intramolecular aldol reaction to afford a compound of formula V. The resultant compound of formula V is then reacted with a wittig reagent to give a compound of formula VI, which is subsequently reduced to afford a compound of formula VII. The protecting group of the ketal ketonic group expressed by W is then removed from the resultant compound of formula VII to give a compound of formula VIII, which is then reacted with a Wittig reagent to afford the compound of formula I.