A. Prabhakar

Self-assembly of cyclic homo- and hetero-β-peptides with cis- furanoid sugar amino acid and β-hGly as building blocks

The design, synthesis and characterization of a new class of peptide nanotubes, self-assembled from cyclic homo- and hetero-β-peptides based on cis-furanoid sugar amino acid and β-hGly residues are described; these results represent the expansion of the conformational pool of cis β-sugar amino acids in the design of peptide nanotubes.

Formation of left-handed helices in hybrid peptide oligomers with cis β-sugar amino acid and L-Ala as building blocks

Residue based control of specific helical folding is explored in hybrid peptide oligomers consisting of alternating L-Ala and cis-beta-furanoid sugar amino acid (FSAA) residues as building blocks; two series of these hybrid oligomers are designed, synthesized and extensively characterized by using NMR, CD, FT-IR and MD simulation studies; results show the co-existence of left-handed 11- and 14/15-helical conformations in these short oligomers of Boc-(alpha/beta) and Boc-(beta/alpha) series.

Pseudoguaianolides from the flowers of Parthenium hysterophorus.

Chemical investigation on the flowers of Parthenium hysterophorus has resulted in the isolation of four new pseudoguaianolides, hysterones A-D along with the known compounds, parthenin, coronopilin, 2beta-hydroxycoronopilin and tetraneurin-A. The structures of the new compounds were established by interpretation of their spectral (1D and 2D NMR) data. The X-ray crystallographic analysis of hysterones A and C was also carried out.

First example of ring expansion of activated quinolines and isoquinolines: novel benzoazepinesElectronic supplementary information (ESI) available: experimental section. See http://www.rsc.org/suppdata/cc/b4/b405100a/

Activated quinoline and isoquinoline undergo unexpected ring expansion by diazocarbonyl compounds via C-C insertion in the presence of 5 mol% of copper triflate to produce ethyl 1H-benzo[b]azepine-1-carboxylate and ethyl 3H-benzo[d]azepine-3-carboxylate, respectively, in excellent yields with a high degree of selectivity

Unprecedented InCl3-catalyzed formation of cis-fused perhydrofuro[2,3-b]oxepines

Abstract 2-Methylindole and its N -substituted derivatives react smoothly with 2,3-dihydrofuran (DHF) in the presence of a catalytic amount of InCl 3 under mild conditions to afford the corresponding 2-methyl-3-perhydrofuro[2,3- b ]oxepin-4-yl-1 H -indole derivatives in fairly good yields with high diastereoselectivity, while 3,4-dihydro-2 H -pyran (DHP) affords exclusively 5,5-di(1 H -3-indolyl)-1-pentanol derivatives in high yields under similar reaction conditions.