HETEROCYCLIC SYNTHESES VIA CARBANIONICALLY INDUCED REARRANGEMENT REACTIONS

Article abstract of DOI:10.1016/S0040-4020(01)91925-8

The easily occuring <1,3>-migrations of sulfonyl and carbonyl functions to neighboring phenyl anions can be utilized for ring expansions by one benzo unit when suitably tailored precursor heterocycles are used.Thus, the 1,2- benzisothiazol dioxide systems 8 and 17 can be transformed into dibenzo<1,4>thiazepin dioxides 12 and 21, respectively, whereas the dibenzo<1,2>- and 1,2,4-benzothiazin dioxide models 35 and 46 give rise to the tribenzo<1,4>thiazocin dioxide and dibenzo<1,2,6>thiadiazocin dioxide systems 38 and 47, respectively.Unexpected formations of heterocyclic systems, namely, spiro<3,1>benzoxazin-5,1'(3H)-isobenzofuran> 55, 3,1-benzoxazin 62, and phenanthridinium-salt 70 took place when phtalimide 52, dibenzoylaniline 56, and biphenylylbenzamide 65 were reacted with t-BuLi.