Search

A full account of the total synthesis of (±)-cassumunins A–C – superior antioxidants and anti-inflammatory agents – is given. Two novel approaches were developed for synthesizing cassumunins. The total synthesis of cassumunins A and B was accomplished in five linear steps from a known aldehyde in good overall yields of 50 and 43%, respectively, featuring a cascade [3,3]-sigmatropic shift (the Claisen rearrangement) and Heck cross-coupling reaction. Consequently, the total synthesis of cassumunin C was accomplished in three linear steps from a known alcohol with an overall yield of 53%. The key features involved in this synthesis are tandem [3,3]-sigmatropic shift, SN 2′ reaction, and aldol condensation. Moreover, a total of eighteen symmetrical and unsymmetrical curcumin analogues were synthesized. [ABSTRACT FROM AUTHOR]

A study aimed to achieve a short and stereoselective route to the trans-hydrindane derivative, which is a potential building block for the synthesis of steroidal and related molecules. The desired results were obtained by the operation of indium, tin, and ruthenium based reagents, starting from a tetrabromo norbornyl derivative.

Research has been conducted on 7-azaspiro[4.5]decan-6-ones. The authors describe the access to these compounds which involves regio- and chemoselective reactions and starts from tetrabromonorbornyl derivatives.

An elegant application wherein a one-pot synthesis of a highly oxygenated strained bis-oxa-bridged compound is delineated from the bis-alpha-diketone and generalized to other substrates is reported. A simple and efficient procedure for the conversion of a 2:1 Diels-Alder adduct between tetrachloro-5,5-dimethoxyclopentadiene and 1,4-cyclohexadiene into a highly symmetric pentacyclic bis-oxa-bridged compounds.

Research is presented concerning the creation of alpha-diketones from vicinal dihaloakenes through a facile conversion process. The production of symmetric, polycyclic bis(alpha-diketone) is discussed.

The formation of a twist-brendane via intramolecular enolate alkylation is described. Conversion of bicyclo[2.2.1]heptane scaffold present in this twist-brendane through a Grob-type fragmentation to unravel a functionalized bicyclo[2.2.2] system which contains all the necessary carbon atoms of the lipophilic core structure of nor-platencin, a platencin analogue is presented. Synthesis of core structure of platencin was also accomplished by extending this strategy to a starting material possessing a surrogate for the exocyclic methylene group. [ABSTRACT FROM AUTHOR]

A selective debromination of tetracyclic dibrominated bis-γ- lactones in the presence of triethylamine and mesyl chloride is reported. Both mesyl chloride and triethylamine are essential for the debromination process. The reduction is proposed to proceed through halophilic substitution of electrophilic bromine. The source of the halophile in this reaction is believed to be triethyl(mesyl)ammonium chloride. The nonoccurrence of debromination in dibromo bis-γ-lactones with tosyl chloride and triethylamine as reagents suggests that the formation of a source of well-dissociated chloride ions during the reaction is necessary. Furthermore, selective debromination of dibrominated bis-γ-lactones was also achieved by using pyridine-thionyl chloride as a reagent. Alternatively, potassium chloride-[18-crown-6] was demonstrated to be a suitable source of chloride ion for the reduction of bromolactones. [ABSTRACT FROM AUTHOR]