TETRAHEDRON: ASYMMETRY Tetrahedron: Asymmetry 11 (2000) 4645–4650 Pergamon New nitrogen containing chiral diselenides: synthesis and asymmetric addition reactions to olefins Marcello Tiecco,* Lorenzo Testaferri, Claudio Santi, Cristina Tomassini, Francesca Marini, Luana Bagnoli and Andrea Temperini Dipartimento di Chimica e Tecnologia del Farmaco, Sezione di Chimica Organica, Universita ` di Perugia, I -06123 Perugia, Italy Received 6 November 2000; accepted 20 November 2000 Abstract A simple synthesis of two new nitrogen containing diselenides, 7 and 8, is described. These compounds were employed as starting materials to effect the asymmetric methoxyselenenylation, the hydroxyselenenyl- ation as well as the cyclofunctionalization of olefins. Starting from 7 all these addition processes occurred with good facial selectivity. Poor results were however obtained with 8. One-pot selenenylation–elimina- tion sequences using catalytic amounts of the diselenide 7 have also been investigated. © 2001 Published by Elsevier Science Ltd. Organoselenium reagents are widely used in organic synthesis to introduce new functional groups into organic substrates under very mild experimental conditions. 1 In recent years, several research groups have described the synthesis of a number of chiral non-racemic diselenides which can be transformed in situ into electrophilic selenenylating agents to effect efficient asymmetric syntheses. 2–7 Diselenides containing a nitrogen atom in the chiral moiety have also been employed as useful ligands in various transformations such as diethylzinc additions to aldehydes, 8 asymmetric hydrosilylation 9 and transfer hydrogenation reactions. 10 Moreover, these diselenides can also be employed in the sequential catalytic stereoselective oxyselenenylation– elimination reactions using ammonium persulfate to generate the electrophilic selenenylating species and to promote the elimination process. 4c Herein we report the synthesis of two new chiral nitrogen containing diselenides and the use of these compounds as precursors of electrophilic species in asymmetric additions of organo- selenium reagents to olefins. The condensation of the commercially available compounds 1 and 2 (Scheme 1) readily afforded the intermediate 3 which was reduced with sodium triacetoxyborohydride in acetic acid * Corresponding author. Tel: +39 075 5855100; fax: +39 075 5855116; e-mail: tiecco@unipg.it 0957-4166/00/$ - see front matter © 2001 Published by Elsevier Science Ltd. PII:S0957-4166(00)00469-9