Synthesis of functionalized nitrocyclohexene derivatives from 2-nitrocycloalkanones, via anionic domino reactions Roberto Ballini, a,p Luciano Barboni, a Giovanna Bosica, a Dennis Fiorini, a Maria Victoria Gil b and Marino Petrini a a Dipartimento di Scienze Chimiche dell'Universita Á, Via S. Agostino n. 1, 62032 Camerino MC), Italy b Departamento de Quimica Organica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain Received 8 March 2001; revised 30 April 2001; accepted 17 May 2001 Abstract ÐThereactionofvarious2-nitrocycloalkanones,atroomtemperature,withacroleinandinthepresenceofmethanolicsolutionof potassiumcarbonate,affordsfunctionalizednitrocyclohexenederivatives,viaananionicdominoreaction. q 2001ElsevierScienceLtd.All rights reserved. Nitrocyclohexene derivatives are useful building blocks of relevant practical interest that provide an ef®cient entry to important frameworks. 1 The classical approach for their synthesis is the Diels±Alder cycloaddition between the appropriate conjugated nitroalkenes and 1,3-dienes. However, although a wide range of the title compounds can be obtained by this method, problems with the prepa- ration of starting materials and/or of regioselectivity are often a serious drawback. 2 The synthesis of complex molecules is traditionally performed by a chain of separate reaction steps, each step requiringitsownconditions,reagents,solvent,andcatalyst. After each reaction is complete the solvent and the waste products are removed and discarded, and the intermediate product is separated and puri®ed. Now, environmental and economic pressures are forcing the chemical community to search for more ef®cient ways of performing chemical transformations. 3 These new issues can be addressed by the development of new synthetic methods that, bringing together simple components, generate complex structures in one pot, much the same way as nature does. Though the origins of this type of process can be dated back to the Robinson±Schopf synthesis of tropinone, 4 it was only recently that terms like `multicomponent reactions' 5 and `domino reactions' 6 became familiar and, in this context, anionic domino transformations appear of great attraction. 7 a-Nitroketones are of particular interest in the formation of carbanions under basic conditions 8 and, additionally, cyclic onesarepronetoringcleavagethroughanucleophilicretro- Claisen condensation. 9 Some years ago we found that the Michael addition of 2-nitrocycloalkanones to conjugated enones, followed by reductive reaction, affords spiroketals via in situ `ring- cleavage/ring-closure'. 10 Later, we reported the one-pot preparation of functionalized 1,4-dicarbonyl derivatives, by conjugate addition of a-nitrocycloalkanones to the appropriate enones, in MeOH/Ph 3 P, then in situ oxidation KMnO 4 ) of the mixture. 11 Incontinuationwiththeabovestudies,wehavenowfoundthat cyclic2-nitroketones 1a±h andacrolein 2 canbeconveniently employed as precursors for the synthesis of functionalized nitrocyclohexenes 3, via an anionic domino reaction Scheme 1). The reaction of 1 with two equivalents of 2 proceeds, at Tetrahedron 57 2001) 6079±6081 Pergamon TETRAHEDRON 0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved. PII:S0040-402001)00581-6 Scheme 1. Keywords: nitrocyclohexenes; domino reactions; 2-nitrocycloalkanones; potassium carbonate; acrolein. p Corresponding author. Tel.: 139-737-402270; fax: 139-737-637345; e-mail: ballini@camserv.unicam.it