Dodecaborate anions of the type B12X122− and B12X11Y2− (X=H, Cl, Br, I and Y=OH, SH, NH3+, NR3+) form strong (Ka up to 106 L mol−1, for B12Br122−) inclusion complexes with γ-cyclodextrin (γ-CD). The micromolar affinities reached are the highest known for this native CD. The complexation exhibits highly negative enthalpies (up to −25 kcal mol−1) and entropies (TΔS up to −18.4 kcal mol−1, both for B12I122−), which position these guests at the bottom end of the well-known enthalpy-entropy correlation for CDs. The high driving force can be traced back to a chaotropic effect, according to which chaotropic anions have an intrinsic affinity to hydrophobic cavities in aqueous solution. In line with this argument, salting-in effects revealed dodecaborates as superchaotropic dianions.

Dodecaborate anions of the type B12X122− and B12X11Y2− (X=H, Cl, Br, I and Y=OH, SH, NH3+, NR3+) form strong (Ka up to 106 L mol−1, for B12Br122−) inclusion complexes with γ‐cyclodextrin (γ‐CD). The micromolar affinities reached are the highest known for this native CD. The complexation exhibits highly negative enthalpies (up to −25 kcal mol−1) and entropies (TΔS up to −18.4 kcal mol−1, both for B12I122−), which position these guests at the bottom end of the well‐known enthalpy‐entropy correlation for CDs. The high driving force can be traced back to a chaotropic effect, according to which chaotropic anions have an intrinsic affinity to hydrophobic cavities in aqueous solution. In line with this argument, salting‐in effects revealed dodecaborates as superchaotropic dianions.

No abstract

Manganese- and cobalt-catalyzed aminocyclization reactions of unsaturated hydrazones are reported. Whereas manganese catalysis provides access to pyrazoline and tetrahydropyridazine alcohols, cobalt catalysis for the first time paves the way for the selective formation of pyrazoline aldehydes. Furthermore, various functional groups including hydroperoxide, thiol derivatives, iodide, and bicyclopentane may be introduced via manganese-catalyzed ring-forming aminofunctionalization. A progesterone receptor antagonist was prepared using the aminocyclization protocol.

We report broad guidance on how to catalyze enantioselective aldehyde additionst on itroalkene or maleimide Michael electrophiles in the presence of unprotected acidic spectator groups,e .g.,c arboxylic acids,a cetamides,p henols,c atechols,a nd maleimide NH groups.R emarkably,t hese l-threonine and l-serine potassium salt-catalyzedr eactions proceedevenwhen the nucleophilic and electrophilic Michaelp artners simultaneously contain acidics pectator groups.T hese findings begin to address the historical non-compatibility of enantioselective catalytic reactions in the presenceo fa cidic moieties and simultaneously encroach on the spectator group toler-ances normallya ssociated with cellular environments.Ac arboxylate salt bridge,f rom the catalyst enabled enamine to the Michaele lectrophile,i s thought to facilitate the expanded Michaels ubstrate profile.Apractical outcome of these endeavours is a new synthetic route to (R)-Pristiq, (À)-O-desmethylvenlafaxine,a na ntidepressant, in the highest yield known to date because no protecting groups are required.Keywords: carboxylate salt bridge;m aleimide;M ichael reaction; nitroalkenes;o rganocatalysis;p eracetic acid para-based phenolic alcohol substrates and involve the addition of acetaldehyde, [4] propanal, [5] or isobutyraldehyde. [6] Scheme1.Enantioselective aldehyde additions to b-nitrostyrenes containing acidic moieties.