NOVEL TRANSFORMATIONS OF 1,2-DIOXETANES - BETA-HYDROXY ETHERS BY ADDITION OF ALKYLLITHIUM REAGENTS

The reaction of 1,2-dioxetanes with alkyllithium reagents was investigated. The 3,3-disubstituted dioxetanes 2a,d and their halogen-substituted analogues 2b,c, which were used as probes to differentiate between the mechanistic alternatives (S(N)2 reactivity vs. single-electron transfer), reacted with n-BuLi to afford the beta-hydroxy ethers 3a-d. Additionally, the epoxide 4 was obtained from dioxetanes 2b,c. The epoxide 5 and a small amount of acetophenone were found in the reaction of dioxetane 2c with triphenylmethyllithium, but only the minor part of the dioxetane-derived products could be identified. The observation of the epoxides 4 and 5 led to the mechanistic conclusion that nucleophilic attack (S(N)2 reactivity) is the most prominent process in this reaction.