New Synthesis of Isoindolo[2,1–b]isoquinolines. Preparation and Aqueous Bioavailability of its Silica Nanoparticles Hybrid System

In this paper we report a new strategy for the synthesis of isoindolo[2,1-b]isoquinolines. N-(1,2- Diphenylethyl)acetamides prepared from the corresponding deoxybenzoins were used as starting material. Double cascade cyclization of the amides promoted by oxalyl chloride and stannyl chloride afforded the oxidized isoindolo[ 2,1-b]isoquinolinone derivatives, which by reduction with a BH3·THF complex gave the 5,7,11b,12- tetrahydroisoindolo[2,1-b]isoquinolines 1b and 1d. Cyclization and reduction were also carried out in one-pot reaction improving the overall yield. DFT structural analysis of the tetrahydro derivatives showed a constrained and planar structure similar to that of camptothecin. SiO2 nanoparticles of 1b (1b-SiNP) were also prepared. This hybrid material provides a very good bioavailability for these compounds in aqueous systems.