Synthesis and cycloaddition reactions of new captodative olefins n-substituted 5-alkylidene-1,3-oxazolidine-2,4-diones

An efficient and straightforward synthesis of the new captodative olefins N-substituted 5-alkylidene-1,3-oxazolidine-2,4-diones (8-10) is described, by a chemoselective oxidative cleavage of the novel exo-2-oxazolidinone dienes (3, 4, and 7), respectively. A study of the reactivity and selectivity of olefins (8-10), was carried out in Diels-Alder cycloadditions to cyclic and unsymmetric acyclic olefins. In all reactions, the corresponding adducts were obtained in high stereo- and regioselectivity. These results have been rationalized in terms of FMO theory by ab initio calculations. 1,3-Dipolar additions of nitrones to olefin (8a) were also highly regioselective, yielding only the C-5 substituted adducts.