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Development of newer improved therapeutic agents with efficient antimicrobial activities continues to draw attention of researchers till date. Moreover, abatement of polluting dyes released from industry with enhanced efficiency is currently being considered as challenging task for people working on material sciences. In the present study, we report a facile biogenic synthesis of gold and silver nanoparticles (NPs) in which aqueous extracts of Paederia foetida Linn. was used as reducing as well as stabilizing agent. The biosynthesized Au and Ag NPs were characterized by UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The photocatalytic activity of these nanoparticles were tested against Rhodamine B (RhB). The antimicrobial activity of these biosynthesized NPs were investigated against four human pathogens viz. B. cereus, E. coli, S. aureus and A. niger. Biogenic silver nanoparticles presented a strong antimicrobial activity against B. cereus (26.13) followed by E. coli (26.02), S. aureus (25.43) and A. niger (22.69). Ag NPs owing to their small size (5-25nm) could have easily penetrate into the cell membrane, disturb the metabolism, cause irretrievable damage finally leading to the microbial cell death. Interestingly biogenic gold nanoparticles didn't show any antimicrobial activity.

Stereoselective total syntheses of (±)-1,14-herbertenediol ( 7 ) and (±)-tochuinyl acetate ( 10 ) and facile total syntheses of (±)-α-herbertenol ( 2 ), (±)-β-herbertenol ( 3 ) and (±)-1,4-cuparenediol ( 8 ) have been successfully accomplished involving intramolecular cyclisation of 3-aryl-3-methyl-6-bromohexanoates and in situ methylation of the resulting cyclopentanecarboxylates as the key reactions.

A stereocontrolled approach to the construction of the angularly ester substituted trans-octahydrophenanthrene ring system related to diterpenes involving an aryl participated diazoketone cyclisation strategy is delineated. The tetrahydrophenanthrenone 7 was prepared from the tetralone 6 through the intermediates 13 , 14 , 16 and 17 . The formyl derivative of 7 was treated with alkaline H2O2 to give the diacid 18 which was converted into the diazomethyl ketone 9 . Aryl participated cyclisation of 9 afforded the enedione 10 which was stereoselectively converted into the keto-ester 11 . The transformation of 11 into the diterpenes 1 and 4 has been efficiently accomplished.

The total syntheses of the herbertane sesquiterpenes (±)-herbertene ( 1 ), (±)-β-herbertenol ( 2 ) and (±)-herbertenediol ( 5 ) have been successfully accomplished involving copper-catalysed conjugate addition of Grignard reagents to unsaturated compounds and α,α-dimethylation of primary esters as key reactions.

The total syntheses of (±)-α-herbertenol 1 , (±)-α-cuparenone 4 and (±)-HM-1 methyl ether 3 have been successfully accomplished involving α,α-dimethylation of the esters 8a, 17 and 8b respectively as key steps.