Diastereoselective synthesis of nitroso acetals from (S,E)-γ-aminated nitroalkenes via multicomponent [4 + 2]/[3 + 2] cycloadditions promoted by LiCl or LiClO₄

• Leandro Lara de Carvalho,
• Robert Alan Burrow and
• Vera Lúcia Patrocinio Pereira

Beilstein J. Org. Chem. 2013, 9, 838–845, doi:10.3762/bjoc.9.96

• diastereoselectivity. In addition, the nitroso acetal 9c was transformed to the pyrrolizidin-3-one derivative 14c, proving the usefulness of the route in the synthesis of an interesting chiral compound. The elucidation of the stereostructures was based on 2D COSY, NOESY and HSQC NMR experiments as well as an X-ray

• diffraction experiment. Keywords: chiral heterodiene; hetero-Diels–Alder reaction; pyrrolizidin-3-one; solvent effect; tandem reaction; Introduction Conjugated nitroalkenes play an important role in cycloaddition reactions providing useful nitrogenated cycloadducts with varied synthetic applications (Scheme

• accomplished. Eleven novel aminated nitroso acetal derivatives were synthesized diastereoselectively, and one of these was transformed into the corresponding pyrrolizidin-3-one derivative to establish the utility of these cycloadducts. Results and Discussion In an exploratory study to screen the best solvent