Diversity-oriented approach to intricate bis-armed spirocycles involving a two directional [2+2+2] co-trimerization and the [4+2] cycloaddition reaction as key steps

We have established a simple synthetic method to bis-armed spirocycles by employing a two-directional [2+2+2] co-trimerization and the [4+2] cycloaddition reaction as key steps. Here, we have used readily available carbonyl compounds to generate a variety of bis-armed spirocycles in a diversity-oriented manner. The sultine derivatives generated here are valuable latent diene equivalents suitable for the Die Is-Alder (DA) reaction to assemble various spirocycles under mild reaction conditions. These sultine derivatives have been prepared by using rongalite, which on treatment with different dienophiles delivered a range of his-armed DA adducts. In addition, these valuable sultine building blocks cleanly rearranged to bis-sulfone derivatives under thermal conditions. (C) 2015 Elsevier Ltd. All rights reserved.