Formic Acid → ((S)-5-Hydroxy-5,6,7,8-tetrahydro-naphthalen-1-yloxy)-acetic acid tert-butyl ester

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Reaction Steps

To a flask containing 124 mg (0.203 mmol) of di-mu-chlorobis[(p-cymene)chlororuthenium(II) ([RuCl2(C10H14)]2, Strem Chemicals, Inc., CAS No. 52462-29-0) and 153 mg (0.416 mmol) of (1S,2S)-(+)-N-p-tosyl-1,2-diphenylethylenediamine (Aldrich, CAS No. 167316-27-0) was added 50 mL of a pre-formed mixture of formic acid and triethylamine (in 5:2 molar ratio), and the resulting mixture was stirred at room temperature for 45 minutes (gas evolution was observed). Then 10 g (36.19 mmol) of (5-oxo-5,6,7,8-tetrahydro-naphthalen-1-yloxy)-acetic acid tert-butyl ester (V, prepared as described above) was added, and the reaction mixture was stirred at 42° C. internal temperature. Upon gas evolution and foaming, the reaction mixture was cooled to 33° C. internal temperature over 1 hour, and then stirred for an additional 24 hours at 33° C. The reaction mixture was then cooled in an ice-water bath, diluted with 50 mL of de-ionized water, and extracted with 100 mL of toluene. The organic layer was separated and washed with 1 M aqueous citric acid (50 mL), saturated aqueous sodium bicarbonate (50 mL), and water (50 mL). The organic phase was then dried over MgSO4, and concentrated azeotropically at 35° C./20 mmHg to a total volume of 30 mL. The resulting solution was co-evaporated with 2×100 mL of toluene to a total volume of 20 mL (product and toluene), which was used in the next step without further purification.

Provenance & Evidence