Triphenylphosphine → Carbamic acid, [2-oxo-1-(phenylmethoxy)-1-azaspiro[3.3]hept-3-yl]-, 1,1-dimethylethyl ester

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Reaction Conditions

Reaction Steps

N-(Benzyloxy)-N2 -(t-butoxycarbonyl)-α-(1-hydroxycyclobutyl)glycinamide (3.50 g, 10 mmole) in 200 ml of dry tetrahydrofuran at 0° C. under argon was treated with 2.4 ml (15 mmole) of diethylazodicarboxylate, then with a solution of triphenylphosphine (5.2 g, 20 mmole) in 50 ml of tetrahydrofuran over 10 minutes, and the mixture stirred at 0° C. for one hour. The yellow color persisted so an additional 0.52 g (2 mmole) of triphenylphosphine was added. After 15 minutes, evaporation in vacuo gave an oil. Trituration with 100 ml of hexane:ethyl acetate (2:1) gave a white solid which was filtered. Chromatography of the filtrate on 800 ml of LPS-1 gave product fractions [Rf=0.8 in hexane:ethyl acetate (1:1)] contaminated with a close-running impurity which was removed by trituration with isopropyl ether, giving the product as a white solid, 1.07 g, melting point 156°-157° C.

Provenance & Evidence