Pyridine → [1-(tert-Butylcarbamoyl-hydroxy-methyl)-2-vinyl-cyclopropyl]-carbamic acid tert-butyl ester

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Reaction Steps

To a solution of the aldehyde 20b (0.054 g, 0.255 mmol) and tert-butylisonitrile (0.043 ml, 0.38 mmol) in dichloromethane (1 ml) and pyridine (0.083 ml, 1.02 mmol) under nitrogen was added trifluoroacetic acid (0.039 ml, 0.51 mmol). After 30 min at rt, the reaction mixture was allowed to reach rt and was stirred for another 2 days. TLC (7:3 hexane-ethyl acetate) and LC-MS monitoring then indicated approx 60% conversion and the reaction mixture was diluted with ethyl acetate (10 ml). The solution was washed successively with aq. 10% citric acid (3×5 ml) and aq. saturated sodium hydrogen carbonate (3×5 ml)), then dried (Na2SO4), filtered and concentrated. The residue was then treated with 1:1:1 aq. 1M LiOH/THF/MeOH (1.5 ml) for 10 min at rt, then diluted with aq. 10% citric acid and taken into ethyl acetate, then dried (Na2SO4), filtered and concentrated. Column chromatography of the residue using 7:3 hexane-ethyl acetate as eluent followed by concentration of the appropriate fractions and drying the residue in vacuum overnight, gave the product as a colourless solid (0.027 g, 0.086 mmol, 34%).

Provenance & Evidence