Utilization of Basic Alumina in a One-Pot Synthesis of 1,4-Diketones, 1,4,7-Triketones, and Dihydrojasmone by Conjugate Addition of Nitroalkanes to Enones
The one-pot synthesis of functionalized 1,4-diketones was achieved in good yields by conjugate addition of primary nitroalkanes to α,β-unsaturated carbonyl compounds on basic alumina without solvent, followed by in situ oxidation with 30% aqueous hydrogen peroxide in methanol. The one-pot syntheses of 1,4,7-triketones and dihydrojasmone are also reported.
Reaction of 1-benzyl-2,5-dicyanopyrrolidine with alkyl halides give unsymmetrical 2,5-dialkylated products (3) in high yields. Hydrolysis of 3 gives γ-diketones which serve as precursors for jasmone analogues having a cyclopentenone framework, while decyanation and debenzylation of 3 lead to 2,5-dialkylpyrrolidine alkaloids in high yields.