The primary objectve of this project is the investigation of intramolecular cycloadditions of nitrosoalkenes, vinynitrosonium ions and nitroalkenes with olefins. We intend to demonstrate the utility of these reaction for the stereroselective construction of complex molecules based on 1) ease of access of precursors, 2) reaction under mild conditions, 3) predictability in creation of stereocenters and 4) various methods (including carbon-carbon bond formation) for the further manipulation of cycloadducts. We will focus our efforts on the synthetic opportunities offered by the latter two ractive heterodienes in both cyclic and acyclic frameworks. The highly reactive vinylnitrosonium ions will be generated by opening of Alpha, Beta-epoxy nitrons derived from aldehydes and ketones. A general preparation of precursors in homochiral form is described. The stereochemical course of cyclization is analyzed in detail with regard to nitrone group, olefin geometry and allylic substituents. The application of the cycloaddition to the preparation of the tuitinanolides, dendramine and aduncin is described. We will investigate the potential of nitroalkenes as 4 Pie components in cycloadditions with unactivated olefins. The nitroalkenes are particularly attractive intermediates due their stability, ease of synthesis and the potential for the cycloaddition products. The preparation of nikroalkenes from chiral aldehydes and the analysis of asymmetric induction is described, as is the potential for catalytic absolute asymmetric induction. The application of this reaction to the synthesis of cockroach pheromone periplanone-B is described. The possibility of effecting a tandem [4 + 2] + [3 + 2] cycloaddition using the nitronate product of a nitroalkene cycloaddition will be explored. Further, refinement of this process into a double intramolecular tandem cycloaddition is proposed.
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