The atropo-enantioselective borohydride reduction with dynamic kinetic resolution of biaryl lactones was catalyzed by an optically active beta-ketoiminatocobalt(II) complex to afford optically active biaryl compounds. Chiral HPLC analysis of the starting biaryl lactones was performed at various temperatures to determine suitable reaction conditions for dynamic kinetic resolution. Various types of axially chiral biaryl compounds were obtained with high enantioselectivity.

For Abstract see ChemInform Abstract in Full Text.

Phosphodiesterase (PDE) 2A inhibitors have emerged as a novel mechanism with potential therapeutic option to ameliorate cognitive dysfunction in schizophrenia or Alzheimer's disease through upregulation of cyclic nucleotides in the brain and thereby achieve potentiation of cyclic nucleotide signaling pathways. This article details the expedited optimization of our recently disclosed pyrazolo[1,5-a]pyrimidine lead compound 4b, leading to the discovery of clinical candidate 36 (TAK-915), which demonstrates an appropriate combination of potency, PDE selectivity, and favorable pharmacokinetic (PK) properties, including brain penetration. Successful identification of 36 was realized through application of structure-based drug design (SBDD) to further improve potency and PDE selectivity, coupled with prospective design focused on physicochemical properties to deliver brain penetration. Oral administration of 36 demonstrated significant elevation of 3',5'-cyclic guanosine monophosphate (cGMP) levels in mouse brains and improved cognitive performance in a novel object recognition task in rats. Consequently, compound 36 was advanced into human clinical trials.

The atropo-enantioselective ring-opening of biaryl lactones with methanol was catalyzed by an optically active AgBF4–phosphine complex to afford axially chiral biaryl compounds. The addition of triisobutylamine provided a dramatic rate acceleration in the reaction. Various types of axially chiral biaryl compounds were obtained with high enantioselectivity.

The enantioselective 1,3-dipolar cycloaddition reaction of nitrones with α,β-unsaturated aldehydes was realized using 3-oxobutylideneaminatocobalt complex catalysts. Varieties of the cobalt(II) and cobalt(III) complexes were screened and the cationic cobalt(III) complex with hexafluoroantimonate was found to be the most effective for the catalytic enantioselective 1,3-dipolar cycloaddition reaction. In the presence of the cobalt(III) hexafluoroantimonate complex, the enantioselective 1,3-dipolar cycloaddition reaction of various nitrones with α,β-unsaturated aldehydes afforded the corresponding isoxazolidines in high yields and with high enantioselectivities. The absolute configuration of the optically active products was determined by X-ray analysis. Reasonable explanations for the enantioselection in the present 1,3-dipolar cycloaddition reaction catalyzed by the 3-oxobutylideneaminatocobalt complex were proposed.