Issue in Honor of Prof. Joan Bosch ARKIVOC 2007 (iv) 84-91 Synthesis of new indolo[1,2-b]isoquinoline derivatives from N-(2- bromobenzyl)indole Roberto Sanz,* ,a José M. Ignacio, a M. Pilar Castroviejo, a and Francisco J. Fañanás b a Área de Química Orgánica, Departamento de Química, Facultad de Ciencias, Universidad de Burgos, Pza. Misael Bañuelos s/n, E-09001, Burgos, Spain b Instituto de Química Organometálica “Enrique Moles” (Unidad Asociada al CSIC), Universidad de Oviedo, C/ Julián Clavería 8, E-33006, Oviedo, Spain E-mail: rsd@ubu.es Dedicated to Prof. Dr. Joan Bosch on the occasion of his 60 th birthday Abstract Optimal conditions have been established for the generation of N-(2-lithiobenzyl)-2-lithio-1H- indole from easily available N-(2-bromobenzyl)-1H-indole. An efficient method was developed for the synthesis of 6,11-dihydroindolo[1,2-b]isoquinoline derivatives by reaction of this indole dianion with carboxylic esters. New and interesting fused indole derivatives have also been synthesized. Keywords: Indoles, organolithiums, dianions, isoquinolines, carboxylic esters Introduction Due to the potent biological activity exhibited by various indole derivatives, there is a continuous demand for novel synthetic methods in this area, as well as for the preparation of new indole derivatives. 1 Also, isoquinolines as well as their derivatives have received considerable attention due to their interesting biological properties. 2 Indolo[1,2-b]isoquinoline derivatives are of considerable pharmacological relevance because they represent C-analogues of tryptanthrin. 3 This kind of fused heterocyclic systems have been prepared mainly by radical cyclization, 4 palladium-catalyzed couplings, 5 and more recently, by a domino “cyclization-lactamization” reaction of functionalized nitriles. 6 In the last years we have developed a new carbolithiation reaction of lithiated double bonds which has allowed us the easy preparation of functionalized indole and pyrrole derivatives. 7 For instance, N-(2-lithioallyl)-2-lithioanilines gave rise to 3-lithiomethylindoles that were trapped with electrophiles (Scheme 1). Moreover, we and others have recently reported that carboxylic ISSN 1424-6376 Page 84 © ARKAT USA, Inc.