9.

Spectroscopic and Density Functional Theory Studies of a New Rosane Type Diterpenoid from Stachys parviflora

Umar Farooq, Khurshid Ayub, Muhammad Ali Hashmi, Rizwana Sarwar, Afsar Khan, Saleha Suleman Khan, Ajmal Khan and Mumtaz Ali

Department of Chemistry, COMSATS Institute of Information Technology, Abbottabad-22060, Pakistan

Department of Chemistry, College of Science, King Faisal University, Al-Hafouf, 31982, Saudi Arabia

H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan

Department of Chemistry, University of Malakand, Chakdara, Dir (L), Pakistan

Abstract: A rosane type diterpenoid has been isolated from the ethyl acetate soluble fraction of Stachys parviflora. The structure elucidation was based primarily on 1D- and 2D-NMR techniques including correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple bond correlation (HMBC), and nuclear Overhauser effect spectroscopy (NOESY). Density functional theory calculations have been performed to gain insight into the geometric, electronic and spectroscopic properties of the isolated diterpenoid. The geometries, vibrational spectrum and electronic properties were modeled at B3LYP/6-31G(d) and the theoretical data correlated nicely with the experimental values. Simulated chemical shifts at B3LYP/6-311+G(2d,p) showed much better correlation with the experimental chemical shifts, compared to B3LYP/6-31G(d) and WP04/6-31G(d).

Keywords: Stachys parviflora; diterpenoid; B3LYP; GIAO; DFT . © 2015 ACG Publications. All rights reserved.