Towards a synthesis of C<SUB>3</SUB>-tribenzohemifullerene, a C<SUB>42</SUB>H<SUB>18</SUB> fragment of [60]fullerene

A short, simple synthesis of C3-trinaphthotriphenylene 6, C42H24, from readily available precursors involving threefold Wittig reactions and threefold oxidative photocyclizations is reported; flash vacuum pyrolysis of 6 in the quest for C3-tribenzohemifullerene 5, C42H18, has so far led only to the formation of monobridged product 12, C42H22

Metal triflates catalyzed efficient synthesis of 3,4-dihydro-2H-1-benzopyrans

Ytterbium triflate efficiently catalyzes an unusual cyclization of o-hydroxybenzaldehydes with 2,3-dihydrofuran and 3,4-dihydro-2H-pyran in the presence of trimethyl orthoformate at ambient temperature to afford a new class of compounds, furo- and pyrano[2,3-b]benzopyrans in excellent yields with high diastereoselectivity. Also, o-hydroxybenzaldehydes reacted smoothly with acetophenones in the presence of a catalytic amount of scandium triflate under similar reaction conditions to give the corresponding 2,4-dialkoxy-2-aryl-3,4-dihydro-2H-1-benzopyrans in high yields

[n]-Ladderanes: a modular access to norbornyl-fused spacer rods

A cycloaddition cascade between norbornene and 1,2-dicarbomethoxycyclobutadiene provides ready access to norbornyl-fused [n]-ladderanes, which undergo further cycloaddition to 1,3-cyclopentadiene to deliver arrays with norbornyl moieties at both the ends. A short synthesis of norbornyl-fused [8]-ladderane is described

Characterization of [n]-ladderanes of unprecedented length: a new record for fused carbocyclic arrays

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A concise entry into the bicyclo[6.4.0]dodecane system present in taxanes. Regioselective Haller-Bauer cleavage in tricyclo[8.2.1.0^2,9]tridecan-13-ones

A short, regio- and stereoselective approach to functionalized cis-bicyclo[6.4.0]dodecane ring system from readily available 1,5-dimethyl-1,5-cyclooctadiene is reported

Synthesis and structural studies of peptides containing a glucose-derived furanoid sugar amino acid

Conformational analysis of peptides containing a glucose-derived furanoid sugar amino acid (Gaa) by detailed NMR and constrained MD studies revealed that peptides with repeating Gaa-Leu-Val units had conformational signatures very similar to those of linear homooligomers of Gaa

Development of 2,3-diazabicyclo[2.2.1]heptane as a constrained azapeptide template and its uses in peptidomimetic studies

2,3-Diazabicyclo[2.2.1]heptane 1 is used for the first time as a peptidomimetic scaffold in the synthesis of a conformationally constrained analogue 6 of azaproline (or azapipecolic acid) containing peptides

Nucleation of β-hairpin structures with cis amide bonds in E-Vinylogous proline-containing peptides

Synthesis and conformational studies of peptides containing the E-vinylogous prolines 1 (VPro1) and 2 (VPro2), Boc-Ala-Val-VPro1-Xaa-Leu-OMe (3, Xaa = Gly; 4, Xaa = Phe), Boc-Ala-Val-VPro2-Xaa-Leu-OMe (5, Xaa = Gly; 6, Xaa = Phe), Boc-Leu-Ile-Val-VPro1-Xaa-Leu-OMe (7, Xaa = Gly; 8, Xaa = Phe), and Boc-Leu-Ile-Val-VPro2-Xaa-Leu-OMe (9, Xaa = Gly; 10, Xaa = Phe), were carried out. It has been shown that both VPro1 and VPro2 lead to the formation of 12-membered intramolecularly hydrogen bonded structures very similar to type VI β-turns with a cis Xaa-VPro amide bond in the major conformers in all the peptides 3-10, resulting in the nucleation of β-hairpin type structures in these molecules in CDCl3

Synthesis and conformational studies of peptidomimetics containing a carbocyclic 1,3-diacid

A rigid carbocyclic scaffold comprising of an all-cis 4,5-dihydroxy-1,3-cyclopentanedicarboxylic acid is developed. Attachment of peptide strands to the carboxylic groups of this novel template led to the peptidomimetics 2 and 3. Conformational analysis by circular dichroism and NMR studies revealed that these molecules adopt a unique folded structure in nonpolar solvent involving intramolecular hydrogen bonding between PheNH of one strand and LeuC=O (in 2) or GlyC=O (in 3) of the other strand. This structure is very different from the structures observed earlier in their sugar counterparts (1). The paper describes in detail the synthesis and structural studies of compounds 2 and 3