We report a simple and efficient procedure for the ligand-free as well as ligand-assisted Suzuki reaction in both pure water and aqueous media. The cross-coupling reactions proceed successfully using phenylboronic acid or potassium phenyltrifluoroborate as a nucleophilic coupling partner. The method can be effectively applied to both activated and deactivated aryl halides yielding quantitative conversions. The catalytic activity of couplings performed in pure water increases when utilizing supramolecular additives, but decreases under standard phase-transfer conditions. Finally, the palladium loading is reducible from 3.0 mol% to 0.4 mol% without any loss of conversion.
A simple and efficient procedure for the Suzuki reaction of phenyl boronic acid or potassium phenyltrifluoroborate with aryl bromides and aryl iodides is reported The reaction can be conducted in pure water or aqueous media.
Enantioselective Biocatalytic Synthesis of (S)-Monastrol. -The first enantioselective biocatalytic synthesis of (S)-monastrol (II) is developed via an unexpected and unusual enzymatic pathway. Whereas attempts for a direct hydrolysis of racemic monastrol are not successful, formation of racemic O-butanoyl monastrol and subsequent enantioselective hydrolysis furnishes O-butanoyl (S)-monastrol with 97 % enantiomeric excess. Subsequent chemoselective cleavage in the presence of another lipase yields the targeted compound in high yield and with a high enantiomeric excess. The method seems to be suitable for other types of racemic phenol esters. -(BLASCO, M. A.; THUMANN, S.; WITTMANN, J.; GIANNIS, A.; GROEGER*, H.; Bioorg. Med.
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