K2S2O8-Mediated Synthesis of Highly Functionalized Pyrroles via Oxidative Self-Dimerization of N-Propargylamines.

An efficient methodology has been developed for the synthesis of tetra- and pentasubstituted pyrroles via oxidative self-dimerization of N-propargylamines catalyzed by silver benzoate in the presence of K2S2O8 in good yields. The protocol provides a simple route for the synthesis of both tetra- and pentasubstituted pyrroles with two carbonyl groups in the side chain. The methodology can be extended toward the synthesis of pyrrolo[3,4-d]pyridazine.

Stereoselective synthesis of hexahydrofuro[3,4-b]furan-4-ol and its dimer via tandem Prins and pinacol rearrangement.

A novel synthetic route for the cyclization of ((4S,5R)-2,2-dimethyl-5-vinyl-1,3-dioxolan-4-yl)methanol with aldehydes to give hexahydrofuro[3,4-b]furan-4-ol and its dimer was developed. A variety of substituted furanol (up to 86%) and its bis-derivatives were obtained in good yields (up to 66%) with excellent diastereo- and enantio-selectivity mediated by borontrifluoride etherate. The dimer was conveniently converted into its corresponding monomer using aqueous zinc(ii) chloride in THF in quantitative yields.

Regio- and Diastereoselective Synthesis of Dihydropyrans and Pyranopyrans via Oxonium-Ene Reaction of ß-Allenols and Aldehydes.

Bismuth trifluoromethanesulfonate can be efficiently used for the preparation of dihydropyrans from ß-allenols and aldehydes by oxonium-ene reaction in good yields. The reaction is highly regioselective. On the other hand, the same reaction with trimethylsilyl trifluoromethanesulfonate at -45 °C affords the hexahydropyrano[4,3- b]pyran skeleton in moderate yields.

Stereo- and Regioselective Synthesis of 4-Vinylpyrrolidine from N-Tethered Alkyne-Alkenol.

Indium(III) chloride can be efficiently used for the synthesis of 4-vinylpyrrolidine from N-tethered alkyne-alkenol in good yields. The reaction is highly stereo- and regioselective.

Diastereoselective synthesis of substituted hexahydrobenzo[de]isochromanes and evaluation of their antileishmanial activity.

Hexahydrobenzo[de]isochromanes and hexahydropyrano[3,4,5-ij]isoquinolines can be efficiently synthesized via Friedel Crafts and oxa Pictet-Spengler reaction of acrylyl enol ethers mediated by triflic acid in good yields. The reaction is highly stereoselective. Two of the hexahydrobenzo[de]isochromanes are found to have moderate antileishmanial activity.