A simple and highly efficient procedure for the synthesis of 3-(benzylthio)-9b-hydroxy-9bH-imidazo[5,1-a]isoindole-1,5-dion derivatives

Developing new synthetic methods for novel nitrogen-containingmolecules is an important area of organic synthesis[1]. As a privileged fragment, the isoindole core is a ubiquitous subunit in many natural and synthetic products with remarkable biological activities. Members of this family have wide applications in medicinal chemistry, being used as antibiotic and antitumor agents[2]. Isoindolinones and many derivatives containing this heterocyclic unitembedded in their skeleton have attracted a great deal of interest, since they represent the common building block of a wide range of naturally occurring and/or bioactive substances.Within this family, 3-hetero-substituted isoindolinones occupy a special place as witnessed by a great number of papers emphasizing their pharmaceutical and medicinal bioactivities[3]. Here, we introduced a novel, convenient, and practical procedure for the synthesis of highly functionalized isoindol derivatives3via oxidative cleavage of 2-(benzylthio)-3a,8adihydroxyindeno[ 2,1-d]imidazoles2with lead(IV) acetate in acetic acid at room temperature (Figure 1).The 3a,8a-dihydroxyindeno[2,1-d]imidazoles2were easily synthesized from the additionreaction of ninhydrin and isothiouronium halide1. These new compounds were undoubtedly characterized by IR, 1HNMR,13CNMR and Mass spectroscopic data.Consequently,the combination of highyields, short reaction times, and mild reaction conditions makes this methodhighly efficient.