424 SURESH THAREJA et al. spectra were recorded on a Varian Mercury YH-300 MHz and using tetramethylsilane (TMS) as the internal standard. Splitting patterns are designated as follows: s, singlet; d, doublet; t, triplet; m, multiplet; b, broad. Elemental analysis has been carried out using PerkinñElmer 2400 elemental analyzer. Thin layer chromatography (TLC) was performed on pre-coated aluminium sheets coated with silica gel 60 F254, 0.2 mm ...