10.22376/ijpbs.2019.10.1.p1-12 Volume 5 Issue 4 2014 (October - December) Acetic acid promoted one-pot Mannich type condensation involving long chain ketones results in the formation of 3-substituted or 3,5-disubstituted 2,6-diarylpiperidin-4-ones in moderate yields. In the absence of acetic acid, the reaction does not proceed to completion. The six member heterocyclic ring adopts a chair conformation, with equatorial disposition of all the substituents. Among the different derivatives of piperidine-4-one, derivatives containing tetrazole and semicarbazone are more potent than the alkyl derivatives against bacteria and fungi. R. SRIKANTH, A. SIVARAJAN AND B. SIVAKUMAR 2,6-diarylpiperidin-4-ones; Mannich reaction; semicarbazone; Antimicrobial activity. 543-551