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A stereoselective strategy for the replacement of the 1,2-dihaloalkene bridge of tetrahalonorbornyl derivatives by an oxygen bridge involving stepwise controlled oxidation, cleavage of the dione thus formed, and reiterative intramolecular S(sub N)2 displacement of two bridgehead halogens is devised. The synthesis of four highly strained pentacyclic bis-oxa-bridged derivatives with interesting structural variations is presented.

Research has been conducted on the gamma-lactone-fused cyclopentanoids. The effect of the tetrahalonorborene derivatives' structural flexibility and stereochemical control on these cyclopentannulated gamma-lactones has been investigated and the details are described.

The role of pi-allylpalladium intermediate in the organic synthesis is central to the palladium-catalyzed reactions of allenes with carbon and heteroatom nucleophiles. The application and reactivity of the pi-allylpalladium species in the synthesis of natural products using allenes and mechanistic aspects of reactions involved are discussed.

A simple computational model explains and predicts pi-facial selectivity in nucleophilic additions to sterically-free carbonyls. The model, based on MNDO, uses two sets of calculations. One measures electrostatic and polarization effects using a test charge to represent the nucleophile, while the other models the hydride ion to determine the added role of orbital interactions. Using these two, the approach is able to reproduce most empirically-established selectivities, especially with the hydride model.

Stereoselective formal synthesis of (_)-neplanocin A from a cyclopentane derivative is described by using an elegant strategy involving reiterative usage of an already existing acetonide protecting group. The acetonide protecting groups that is carried forward intact right from the starting adduct to an advanced intermediate is shuffled around twice as in a relay race through the synthetic sequence, which has avoided unnecessary employment of additional protecting groups.

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.

Nitroarenes were chemoselectively reduced to the corresponding amines using zinc and aqueous ammonium salts in ionic liquids as a safe and recyclable reaction medium. Our results specify the effect of ammonium salts in the process; the combination of Zn/NH4Cl in [bmim][PF6] or Zn/HCO2NH4 in [bmim][BF4] were the suitable conditions for the reduction of nitroarenes. Azobenzenes were also smoothly reduced to hydrazobenzenes with Zn/HCO2NH4 (aq.) in recyclable [bmim][BF4] without any over reduction to the corresponding anilines. [Copyright &y& Elsevier]