SHORT COMMUNICATION DOI: 10.1002/ejoc.200900800 Vinylic Substitutions Promoted by PhSeZnCl: Synthetic and Theoretical Investigations Stefano Santoro, [a] Benedetta Battistelli, [a] Lorenzo Testaferri, [a] Marcello Tiecco, [a] and Claudio Santi* [a] Keywords: Selenium / Zinc / Vinylic substitution / Nucleophilic substitution / DFT calculations Vinyl selenides can be easily obtained through nucleophilic substitution of the corresponding halides by using PhSeZnCl in THF as well as “on water” conditions. The reaction is ste- reospecific with retention of the alkene geometry. The only exception has been observed in the reaction conducted on a β-chloro-α,β-unsaturated ketone, which afforded the (Z) Introduction Phenyl selenolate is one of the most convenient organo- selenium reagents, and its role in effecting many synthetic transformation is known. [1] A number of procedures for the “in situ” generation of selenolates have been reported, [2] but most of them suffer from serious drawbacks such as bad smelling, moisture sensitivity, strong basic reaction condi- tions, use of hazardous organic solvents. Recently, the use of zinc as reducing agent for the preparation of selenols was reported, [3] and we demonstrated that treatment of com- mercially available PhSeCl with a stoichiometric amount of zinc powder in refluxing THF leads to the corresponding solid and air-stable zinc selenolate 1 through an oxidative insertion of zinc into the selenium–chlorine bond [4] (Fig- ure 1). Figure 1. Bench-stable selenolate PhSeZnCl (1). This reagent has been efficiently employed in the ring opening of epoxides, and we reported also an unexpected rate acceleration when these reactions were effected by “on water” conditions. [5] [a] Dipartimento di Chimica e Tecnologia del Farmaco, Università di Perugia, via Del Liceo 1, 06123 Perugia, Italy Fax: +39-075-5855116 E-mail: santi@unipg.it Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/ejoc.200900800. Eur. J. Org. Chem. 2009, 4921–4925 © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 4921 product starting from either the (E) or (Z) isomer. DFT calcu- lations have been performed in order to investigate the reac- tion mechanism, the stereochemistry of the process and the role of the zinc atom. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) Here we report that 1 can be used for the synthesis of vinylic selenides starting from the corresponding halides. Many vinylic sulfide, selenide and telluride preparations in- volve the use of expensive catalysts or not readily available starting materials. [6] Moreover, often the products are ob- tained as mixtures of regio- or stereoisomers. Vinylic sele- nides are intermediates of great synthetic interest, and their versatility in organic synthesis is well documented through the publication of a number of reviews and books. [6b,7] They combine the functional transformations achieved by the well-known reactions of organoselenium compounds (e.g. selenoxides, syn elimination) with the ability of carbon–car- bon bond-forming reactions involving the double bond, as- sociated with the capacity of selenium to stabilize adjacent positive and negative charges (Scheme 1). Scheme 1. Vinylic selenides as useful synthetic intermediates.