Preparation of 2,2,6-trisubstituted 7-oxa-1-azabicyclo[2.2.1]heptanes from 4-nitro-1-butene derivatives. A route to 2,2,6-trisubstituted-4- hydroxypiperidines

Article abstract of DOI:10.1016/S0040-4039(98)02357-0

4-Nitro-1-butene derivatives 2 readily available from the palladium(0)- catalyzed C-allylation of nitroalkanes were converted into 7-oxa-1- azabicyclo[2.2.1]heptane derivatives 5 in three easy steps including an intramolecular 1,3-dipolar cycloaddition reaction of N-(3-alkenyl)nitrones. The palladium catalyzed hydrogenolysis of the compounds 5 afforded 2,2,6- trisubstituted-4-hydroxypiperidines. The oxidation of 5 by 3 equiv. of m- chloroperbenzoic acid (MCPBA) gave acyclic β-hydroxy-δ-nitroketones 9 in high yield.