Synthesis and regiochemistry of spiro indane-1,3-dione compounds

摘要

Spiro indane-1,3-dione compounds have been synthesized by 1,3-dipolar cycloaddition of ninhydrin, l-proline, and an alkene (either a chalcone or an (E)-β-arylnitrostyrene). All these reactions proceed with good yield and with high regioselectivity and stereoselectivity. The structures were studied by NMR spectroscopy, MS, and X-ray diffraction analysis. It was found that these two kinds of alkene lead to different regioselectivity. This study has provided information about the regioselectivity of 1,3-dipolar cycloaddition reactions: regioselectivity may be controlled by π-π stacking state; the order of stability of stacking of the Ar and EWG part with the indane-1,3-dione part is: benzoyl group > phenyl group > nitro group.