European Journal of Organic Chemistry

Residual dipolar couplings (RDCs), which become observable after the compound in question is introduced into an anisotropic environment, are increasingly important as additional NMR restraints in the determination of the structure of organic compounds. An overview of the alignment media for organic compounds and the corresponding measurement methods and applications is given.

The stereoselective synthesis of the N-protected 11-amino-azaelliptitoxin analog (11R,11aS,5R)-15 from (S)-glycidol (7) is described. The key intermediate of this original synthetic approach is the first prepared enantiopure -amino aldehyde 9 ( 99% ee), inducing the expected configurations of the two other stereogenic centers C-5 and C-11 of the final target 15.

The palladium-catalyzed coupling of arylboronic acids with ethyl glyoxylate provides a straightforward method for the synthesis of mandelic esters. Pd₂(dba)₃·CHCl₃ in combination with 2-di-tert-butylphosphanylbiphenyl as the catalytic system and Cs₂CO₃ as the base were used. The reaction tolerates a wide range of functionalizedboronic acids.

β-Pyrenylamino acid derivatives have been synthesized from dehydroamino acids by using several types of reactions, namely, Michael addition, substitution and Suzuki cross-coupling reactions. The latter type of reaction was also applied to the synthesis of β-(pyren-1-yl)dehydrodipeptides. The electrochemical behaviour and photophysical properties of some of the compounds were studied.

The mild and selective acetolysis of 6-deoxysugar (rhamnose, fucose, and quinovose) derivatives under thermodynamic and kinetic conditions has been investigated. The products obtained are highly dependent on the competition between exo and endoanomeric oxygen by the Ac⁺ ion.

The 3′-C-hydroxymethyl-branched Locked Nucleic Acid (LNA) monomer was synthesized in 19 synthetic steps from diacetone-α-D-glucose. The nucleoside is locked in an N-type conformation with the hydroxymethyl substituent in a pseudoaxial position.

A variety of mono- and polytopic 1,2,3-triazole β-CD derivatives have been synthesized by click chemistry. The synthetic procedure is based on the Cu^I-catalyzed azide–alkyne cycloaddition reaction between hydroxylated or randomly methylated β-CD monoazides and alkynyl precursors. Easy to use, the reaction is also high-yielding for many molecules.

3,4,6-Tri-O-benzyl glycal epoxides have been efficiently converted into four sugar–iminosugar hybrid molecules made up of D-glucose and D-galactose with pyrrolidine-based iminosugars. These hybrid molecules were found to be moderate glycosidase inhibitors.

Multivalent amino-substituted bis- and tris(armed) oligonitrile derivatives are synthesized by two alternative reaction pathways. In the solid state some derivatives show inter- and intramolecular hydrogen bonding. They act as chelating ligands with various metal ions to form novel types of coordination compounds.

Computational evidence at the B3LYP/6-31G* level of theory suggests that the 6,7-diamino-substituted helical “Möbius” 1H-aza[11]annulene is aromatic and a neutral ground state on its potential surface.

3-Deoxygalactal was synthesized by using the tandem RCM/isomerization method. The tandem sequence can also be extended by a dehydrogenative silylation step, resulting in the formation of a 3-deoxy glycal bearing two orthogonally protected alcohol groups.

The total synthesis of the carbohydrate portion of steroidal saponins, isolated from Calamus insignis, is reported. A simple route was followed, starting from commercially available D-glucose and L-rhamnose, through high-yielding protecting group manipulation strategies.

A combination of [CpRu(η⁶-naphthalene)][PF₆] and enantiopure pyridine-mono-oxazoline ligands catalyze the regio- and enantioselective decarboxylative Carroll rearrangement of allyl β-keto esters into γ,δ-unsaturated ketones.

A straightforward synthesis of orthogonally protected PNA monomers is described. The new monomers are demonstrated to be valid building blocks for PNA oligomerization.

A novel, efficient and atom-economical reaction for the preparation of diversely substituted aryl ketones by the simple treatment of terminal aryl alkynes and benzylic alcohols with catalytic FeCl₃ has been developed. The reaction is highly solvent dependent; nitromethane was the best solvent for this transformation. The mechanism of this reaction is proposed and discussed.

Bis(diisopropylamino)carbene deoxygenates the carbonyl group of aroylimines Ar–C(O)–N=C(CF₃)₂ to form alkenes.

The advanced intermediate 4 in the synthesis of new omuralide–salinosporamide A hybrids was prepared in a few steps from pyrrolinone 5, which wasderived from methyl pyroglutamate, with a regio- and stereoselective C-(4-methoxybenzyloxymethyl)-N-methylnitrone cycloaddition.

The structure and conformational behaviour of the core region of the lipopolysaccharide isolated from S. fredii SMH12 have been studied. The results indicate that the core oligosaccharide contains a disaccharide made up of α-D-glucopyranuronic acid (1→4)-linked to D-Kdo. In solution, this disaccharide exists as an equilibrium of three different structures.

1-Azulenyl methyl sulfide reacts with highly electrophilic trifluoromethanesulfonates of N-heterocycles to give 1-methylthio-3-(dihydroheteroaryl)azulenes in good yields. Treatment of these azuleneswith KOH or tBuOK afforded 1-methylthio-3-(heteroaryl)azulenes in good yields. The redox behavior of the 1-methylthio-3-(heteroaryl)azulenes was examined by cyclic voltammetry.

The chemoselective control of the synthesis of N-alkyl-4-(trihalomethyl)-1H-pyrimidin-2-ones is reported.

A convergent synthesis of a highly oxygenated phenanthridone, featuring a Suzuki cross-coupling and intramolecular aza-Michael addition reaction sequence to generate the fused B–C ring juncture, is accomplished.