反应详情

The requisite (4S)-1,4-dimethyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine was prepared in the following manner. Reaction of C8 at elevated temperature with trimethylboroxin in the presence of sodium carbonate and tetrakis(triphenylphosphine)palladium(0) afforded 1,4-dimethyl-1H-pyrazolo[3,4-c]pyridine. This material was reduced using the method described for synthesis of C9 from C8 in Example 2; the product was subjected to supercritical fluid chromatography to separate the enantiomers (Column: Chiral Technologies, Chiralpak IC, 5 μm; Eluent: 4:1 carbon dioxide/methanol). The second-eluting enantiomer was collected and used for synthesis of Example 20. The absolute stereochemistry was arbitrarily assigned.