Abstract
Active methylene compounds were allowed to react with 9-phenylxanthylium perchlorate (I) and with 9-phenylthioxanthylium perchlorate (II). The products were only those that were formed by the attack of 9-position of I or II by the active methylene compound. When t-BuOK was used as a base, deacetylation occurred in the reaction between I and acetylacetone. When triethylamine was used as a base, expected results were obtained. By the reaction of I or II with KCN, V or VI, in which a cyano group was introduced to 9-position, was obtained with a high yield. The reactivities of I and II in electrophilic and nucleophilic reactions were discussed from the viewpoints of qualitative electronic theory and the theoretically calculated reaction indices. The results indicated that the contribution of the carbonium ion structure is more in I than in II and that I is more reactive than II in the nucleophilic reaction. The contribution of the onium ion structure is more in II than in I. Therefore, II is theoretically reactive than I in the electrophilic reaction. This conclusion well agrees with experimental results.
