Total synthesis and cytotoxic activity of stellatin

Convenient Syntheses of 3-Aryl-3,4-Dihydroisocoumarins

A convenient method for the synthesis of naturally occurring 3,4-dihydroisocoumarins by judicious use of Friedel-Craft acylation, regioselective formylation and oxidative cyclisation reactions is described. O-methylated analogues of montroumarin and thunberginols C and D and have been synthesised using 3,5-dimethoxyphenylacetic acid as a starting material. Furthermore, the starting material 3,5-dimethoxyphenylacetic acid was synthesised by a route involving an oxidative Nef reaction.

Design, synthesis and docking studies of some novel isocoumarin analogues as antimicrobial agents

The isocoumarins have been designed and prepared by incorporating the NSAIDs to discover potential inhibitors of UDP-N-acetylmuramyl-l-alanine ligase (MurC).

Total synthesis of cytotoxic metabolite ( ± )-desmethyldiaportinol from Ampelomyces sp

A concise total synthesis of ( ± )-desmethyldiaportinol isolated from Ampelomyces sp. is described. Microwave-assisted cyclocondensation of 3,5-dimethoxyhomopthalic acid with 3,4-dibromobutanoyl chloride afforded the 3-(2,3-dibromopropyl)-6, 8-dimethoxyisocoumarin in 2-3 min as the pivotal step. The 3,4-dibromobutanoyl chloride was itself synthesised from 3-butenoic acid via bromination in carbon tetrachloride at room temperature to yield 3,4-dibromobutanoic acid followed by reaction with thionyl chloride. The replacement of bromo- by hydroxyl substituent was achieved under mild conditions involving the refluxing in a mixture of acetone and water to provide ( ± )-3-(2,3-dihydroxypropyl)-6,8-dimethoxyisocoumarin which on complete demethylation furnished the title natural product.

Total synthesis and antibacterial screening of ( ± )-7-butyl-6,8-dihydroxy-3-pentyl-3,4-dihydroisochromen-1-one

A new total synthesis of ( ± )-7-butyl-6,8-dihydroxy-3-pentyl-3,4-dihydroisochromen-1-one, isolated as R-enantiomer from Geotrichum sp., has been described. Reaction of 4-butyl-3,5-dimethoxyhomophthalic anhydride with hexanoyl chloride in the presence of 1,1,3,3-tetramethyl guanidine and triethyl amine afforded 7-butyl-6,8-dimethoxy-3-pentylisochromen-1-one, which was converted into corresponding 3,4-dihydroisochromen-1-one by successive ring opening and reduction. Final demethylation to furnish the natural product was achieved using anhydrous aluminum chloride in ethanethiol. The target compound and the intermediates were subjected to antibacterial evaluation against 10 bacterial strains using levofloxacin as standard.