2.1. General
Melting point was determined on electro thermal (UK-made)
apparatus on centigrade scale and was uncorrected. Ultra-violet
absorption spectrum was recorded on Perkin-Elmer
Lambda Bio 20 UV spectrophotometer. Infrared spectrum
was recorded on Perkin-Elmer 1710 infrared Fourier Transform
spectrometer. 1H and 13C NMR were recorded on a Bruker
AVANCE DRX-300 (300 and 75 MHz) equipped with
5 mm inverse multinuclear probe head. Tetramethyl silane
(TMS) was used as an internal standard and chemical shift values
are expressed in d (ppm) values, coupling constant (J) in
Hertz. ESMS, electro spray mass spectra, were recorded on a
Micromass Quattro II triple quadrapole mass spectrometer.
EIMS, electron impact mass spectra, were recorded at 70 eV
on JEOL-JMS D-100 spectrometer. Column chromatography
was performed over silica gel (60–120 mesh, Qualigen) and
TLC was carried out on a silica gel G (10–40 l, Merck). Paper
chromatography (PC) was carried out on Whatman paper
number 1 in descending mode in n-BuOH–AcOH–H2O
(4:1:5, v/v/v), developed by spraying with silver nitrate solution
in acetone followed by NaOH solution in methanol.