Ethyldi-(4-trifluormethylphenyl)phosphine → tert-butyl (3S)-3-amino-3-(5-phenylmethoxypyridin-3-yl)propanoate

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Reaction Steps

To chloro(1,5-cyclooctadien)rhodium(I) dimer (29 mg, 60 μmol) and (R)-(−)-1-[(S)-2-Di-tert.-butyl-phosphino)ferrocenyl]ethyldi-(4-trifluormethylphenyl)phosphine (81 mg, 120 μmol) under an argon atmosphere was added 2,2,2-trifluoroethanol (4 mL) and the solution was stirred for 40 minutes. To tert-butyl 3-amino-3-[5-(benzyloxy)pyridin-3-yl]prop-2-enoate (1.95 g/5.97 mmol) in degassed 2,2,2-trifluoroethanol (10 mL) in a pressure vessel was added the rhodium catalyst solution and the solution was stirred for 22 hours at 50° C. under hydrogen pressure of 10 bar. The addition of an identically prepared rhodium catalyst solution in 2,2,2-trifluoroethanol (4 mL) was repeated and stirring under 10 bar hydrogen pressure at 50° C. was continued for additional 16 hours. The solution was concentrated under reduced pressure and the residue was purified by chromatography on silica gel (ethyl acetate in hexane, 12 to 100% followed by methanol in ethyl acetate 0 to 15%) to yield 1.16 g of enantiomerically enriched tert-butyl (3S)-3-amino-3-[5-(benzyloxy)pyridin-3-yl]propanoate.

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