Synthesis of Highly Substituted Functionalized Piperidine Derivatives via Oximation Reaction and its Anti-Microbial Activity

The synthesis of Nitrogen base heterocycles particularly highly substituted piperidine are very important structural motif which is present in numerous natural alkaloids including piperine, nicotine, coniine etc and non-natural substances too. The piperidine is extracted from black pepper1,2, Psilocaulon absimile (Aizoaceae)3 and Petrosimonia monandra4.   The functionalized piperidine derivatives are ubiquitous building block in synthesis of pharmaceuticals and fine chemicals, consequently it attract interest, both for their synthetic challenges,5 and also their value in synthetic chemistry6 and diverse biological activity.7 The present work includes the synthesis of highly functionalized piperidine derivatives using the Oximation of Michael adducts (scheme 3). The target product was oxime for further reaction but instead of the required oxime as product the side product with six member heterocylic product was formed as major product. The yield of side product was depends on time and thermodynamic conditions. Owing to the new results which were confirmed by singe crystal X-rays and NMR data, we have developed this methodology which gives easy access to the synthesis of highly substituted piperidine (Scheme 3). This strategy is very simple and efficient to have 2,3,4,6 substituted nitrogen containing heterocycle as Piperidine.