A new family of molecular photoswitches based on arylidenehydantoins is described together with their synthesis and photochemical and photophysical studies. A series of hydantoin derivatives have been prepared as single isomers using simple and versatile chemistry in good yields. Our studies show that the photostationary states of these compounds can be easily controlled by means of external factors, such as the light source or filters. Moreover, the detailed investigations proved that these switches are efficient (i.e., they make efficient use of the light energy, are high fatigue resistant, and are very photostable). In some cases, the switches can be completely turned on/off, a desirable feature for specific applications. A series of theoretical calculations have also been carried out to understand the photoisomerization mechanism at the molecular level.

The western segment of hygrocins A–B has been synthesized through the coupling of a chiral C5–C13 synthon with the sterically demanding hexasubstituted naphthalenic core. The C5–C13 chiral fragment has been assembled via a stereoselective Johnson orthoester rearrangement of an optically pure allylic alcohol derived from d-glucose. Our studies lay the platform for the determination of the absolute configuration of the unassigned C8-stereocenter of the title compounds in addition to the completion of the total synthesis of the unique ansamacrolides hygrocins A and B.

A facile synthesis of the western segment of divergolides C and D has been developed. Exploratory studies with two disconnections, i.e., C4–C5 vs C5–C6, for elaboration of the ansa bridge to the sterically demanding hexasubstituted naphthalenic aromatic core using a chiral synthon assembled from d-glucose via a stereoselective Johnson orthoester rearrangement is described. The studies set the stage for the completion of the total synthesis of the biologically important novel ansamycins, divergolides C and D, and their structural congeners.

The total syntheses of oroidin, hymenidin and clathrodin are reported via the intermediacy of an imidazo[1,2-a]pyrimidine derivative. The chemistry described herein obviates the need for expensive guanidine reagents, multiply protected prefunctionalized 2-aminoimidazole synthons, or the need for laborious olefinations thereby achieving synthetic efficiency amenable to scale-up. The approach outlined in this manuscript provides an opportunity for further functionalizations through the imidazo[1,2-a]pyrimidine core and through functional groups placed strategically on the side chain.

Herein, we report the synthesis and the screening results of the unique acyl imidazopyrimidinyl and acyl imidazolyl structural analogues of oroidin as inhibitors of biofilm formation that have minimal or no microbicidal effect. A focused library based on the marine natural product oroidin scaffold was synthesized and assayed for antibacterial and anti-biofilm activity against medically relevant bacterial pathogens. Based on the structure–activity relationship (SAR) studies, it is concluded that the most active analogues are those that contained a 2-aminoimidazole motif and a brominated pyrrolecarboxamide subunit with a carbonyl functionality in the side chain.

Herein, we describe a facile synthesis of the naphthoquinone fragment of the aromatic core of the novel ansamycins such as hygrocins A–B and the divergolides C–D, starting from the inexpensive 2-hydroxy-3-methylbenzoic acid. We demonstrate the utility of naphthalenic synthon for further elaboration of the ansabridge via C5–C6 bond formation by employing a commercially available sterically demanding organomagnesium reagent as a model ansa chain. Facile conversion of the resulting alcohol to the naphthoquinone fragment of the targets in one pot has also been realized. These model studies set the stage for the completion of total synthesis of the biologically important novel ansamycins.

Our attempts to prepare indolyl acid (3), enroute to prenostodione (2), from phenyl-hydrazine following a reported procedure of Fischer-Indole synthesis rather lead to ethyl 2-(5-oxo-1-phenyl-2,5-dihydro-1H-pyrazol-3-yl)acetate as a major product, which underwent facile condensation with aldehydes to provide the pyrazolones. Intrigued by the opportunity for the diversity oriented synthesis of substituted pyrazolones, we have developed a facile one pot approach for pyrazolones and screened for antibacterial activity and, herein, results are reported.

The total syntheses of oroidin, hymenidin and clathrodin are reported via the intermediacy of an imidazo[1,2-a]pyrimidine derivative. The chemistry described herein obviates the need for expensive guanidine reagents, multiply protected prefunctionalized 2-aminoimidazole synthons, or the need for laborious olefinations thereby achieving synthetic efficiency amenable to scale-up. The approach outlined in this manuscript provides an opportunity for further functionalizations through the imidazo[1,2-a]pyrimidine core and through functional groups placed strategically on the side chain.