To a solution of benzyl 3-t-butyl-1H-pyrazole-5-carboxylate (0.100 g, 0.387 mmol, synthesized by trans-esterification of commercially available ethyl 3-t-butyl-1H-pyrazole-5-carboxylate), 2-(t-butoxycarbonyl)-3-(methoxycarbonyl)-1,2,3,4-tetrahydroisoquinolin-6-ylboronic acid (0.195 g, 0.581 mmol, made analogously to Example A56) and pyridine (0.092 g, 1.16 mmol) in methylene chloride (4 mL) was added copper(II)-acetate (0.105 g, 0.581 mmol) and the resulting mixture was stirred at Rt for 1d. The mixture was directly loaded on a silica gel column, chromatographed and concentrated to yield 2-t-butyl 3-methyl 6-(5-(benzyloxycarbonyl)-3-t-butyl-1H-pyrazol-1-yl)-3,4-dihydroisoquinoline-2,3 (1H)-dicarboxylate (171 mg, 81% yield) as a colorless foam. MS expected 548.3 found 548.3. To this material (0.136 g, 0.248 mmol) in EtOAc (5 mL) was added palladium on charcoal (10%, 0.013 g, 0.012 mmol) and the mixture was stirred under an atmosphere of H2 overnight. The mixture was filtered and the filtrate was concentrated to yield 1-(2-(t-butoxycarbonyl)-3-(methoxycarbonyl)-1,2,3,4-tetrahydroisoquinolin-6-yl)-3-t-butyl-1H-pyrazole-5-carboxylic acid (114 mg, 100%) as a colorless foam. MS expected 458.2 found 458.3.
