Diethyl Ether → (2R)-2-Amino-4-(7-hydroxy-2-oxo-2H-1-benzopyran-4-yl)butanoic acid

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Reaction Steps

(2S)-2 Benzyloxycarbonylamino-5-oxo-heptanedioic acid 1-benzyl ester 7-ethyl ester from the previous step (2.35 g, 5 mmol) was added slowly to resorcinol (3 g, 25 mmol) in methanesulfonic acid (20 ml) and stirred for two hours at room temperature. Five volumes of ether were then added to the mixture and was cooled to −30° C. The precipitate was washed with cold ether, dissolved in water, filtered, and lyophilized. L-(7-hydroxycoumarin-4-yl)ethylglycine was purified by reverse phase HPLC to afford a brown solid in 50% yield (YMC AA12S052503WT column, 12 ml/min flow rate, from 10% to 90% CH3CN, 0.1% TFA (w/v) in water, over the course of 12 min). 1H-NMR (DMSO): δ 2.06 (s, 2H), 2.70-2.90 (m, 2H), 3.82-4.0 (m, 1H), 6.06 (s, 1H), 6.75 (dd, J=8.8, 2.4, 1H), 6.82 (d, J=2.4, 1H), 7.62 (d, J=8.8, 1H), 8.17 (s, 3H). LC-MS (ESI) calc. for C13H14NO5 (M+H+) 264.08 Da, obsd. 264.0 Da.

Provenance & Evidence