Highly enantioselective asymmetric transfer hydrogenation (ATH) of α-phthalimide ketones

Total Synthesis of the Acetyl CoA Carboxylase Inhibitor Soraphen A: Asymmetric Tsuji Reduction Enables Successive Olefin Metathesis

The total synthesis of soraphen A, a myxobacterial metabolite and inhibitor of acetyl CoA carboxylase, was completed in 11 steps (longest linear sequence), less than half the steps previously required. Seven metal-catalyzed processes were deployed to unlock step-economy (comprising five asymmetric processes and four C-C bond formations). The present route does not utilize chiral auxiliaries, and four of five C-C bond formations exploit non-premetalated partners. To maximize convergency, an asymmetric Tsuji reduction was developed using a Pd-AntPhos catalyst that allows a metathesis-inactive allylic carbonate to serve as a masked terminal olefin, thereby enabling successive olefin metathesis events.

Synthesis, Absolute Configuration, Antibacterial, and Antifungal Activities of Novel Benzofuryl β-Amino Alcohols

A series of new benzofuryl α-azole ketones was synthesized and reduced by asymmetric transfer hydrogenation (ATH). Novel benzofuryl β-amino alcohols bearing an imidazolyl and triazolyl substituents were obtained with excellent enantioselectivity (96-99%). The absolute configuration (R) of the products was confirmed by means of electronic circular dichroism (ECD) spectroscopy supported by theoretical calculations. Selected benzofuryl α-azole ketones were also successfully asymmetrically bioreduced by fungi of Saccharomyces cerevisiae and Aureobasidium pullulans species. Racemic and chiral β-amino alcohols, as well as benzofuryl α-amino and α-bromo ketones were evaluated for their antibacterial and antifungal activities. From among the synthesized β-amino alcohols, the highest antimicrobial activity was found for (R)-1-(3,5-dimethylbenzofuran-2-yl)-2-(1H-imidazol-1-yl)ethan-1-ol against S. aureus ATCC 25923 (MIC = 64, MBC = 96 μg mL-1) and (R)-1-(3,5-dimethylbenzofuran-2-yl)-2-(1H-1,2,4-triazol-1-yl)ethan-1-ol against yeasts of M. furfur DSM 6170 (MIC = MBC = 64 μg mL-1). In turn, from among the tested ketones, 1-(benzofuran-2-yl)-2-bromoethanones (1-4) were found to be the most active against M. furfur DSM 6170 (MIC = MBC = 1.5 μg mL-1) (MIC-minimal inhibitory concentration, MBC-minimal biocidal concentration).

Chiral-at-metal iridium complex for efficient enantioselective transfer hydrogenation of ketones

A pyrazole co-ligand permits a low loading iridium-catalyzed asymmetric transfer hydrogenation which is proposed to proceed through metal–ligand cooperativity.