SUBSTITUENT SELECTION FOR DESIGN AND
SYNTHESIS OF ANTIMICROBIAL 1,3
OXAZINES: A TOPLISS MODIFIED APPROACH
RAMESH SAWANT*, LOKESH BHANGALE, JYOTI WADEKAR,
PANDURANG GAIKWAD
Department of Pharmaceutical Chemistry, Pd. Dr. Vithalrao Vikhe Patil
Foundation’s College of Pharmacy, Vilad Ghat, Post- MIDC,
Ahmednagar- 414 111, Maharashtra, India
*corresponding author: sawantrl@yahoo.com
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Abstract:

The purpose of the present work was to select substituents by using Topliss
modified approach to synthesize new 1,3 oxazines with antimicrobial effect. In the series of 6-[4-substitutedphenyl]-4-phenyl-6H-1,3-oxazin-2-amines and N-[6-(4-substitutedphenyl)- 4-phenyl-6H-1,3-oxazinyl] acetamides, substituents at fourth position of the phenyl ring were selected according to the Topliss modified approach and the initial set of compounds was synthesized. The antimicrobial screening revealed that compounds with methoxy substituent having negative sigma (-0.04) and negative pi (-0.27) values are good antimicrobial agents showing low minimum inhibitory concentration (MIC). The hydroxyl group substituent with more negative sigma (-0.61) and pi (-0.37) values was selected to synthesize final set compounds and were found better antimicrobials than the initial set of
compounds. The study revealed that electron donating polar substituents at fourth position of the phenyl ring are required to improve antimicrobial potential in the series of 6-[4- substitutedphenyl]-4-phenyl-6H-1,3-oxazin-2-amines and N-[6-(4-substitutedphenyl)-4- phenyl-6H-1,3-oxazinyl] acetamides..

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