L-Tyrosine → tert-Butyl (2S)-2-amino-3-(4-(3-ethoxycarbonylpropyloxy)phenyl)propionate

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Reaction Steps

Potassium tertbutylate (3.36 g, 30 mmoles) is added to a solution of tyrosine 4-1 (5 g, 21 mmoles) in 100 ml of DMF, followed by agitating for 30 minutes while cooling down in a water+ice bath, then the bromoester (ethyl 4-bromobutanoate) (3.6 ml, 25 mmoles) in solution in 10 ml of DMF is added. The reaction medium is agitated overnight at ambient temperature, followed by evaporating under reduced pressure, taking up the dry extract in a water/ethyl acetate mixture, decanting, drying the organic phase, filtering, evaporating then purifying by chromatography eluting with a Heptane/ethyl acetate gradient (100/0→0/100). 5.2 g of the expected product 4-2 is obtained.

Provenance & Evidence