Sodium Hydroxide → 4-[bis(tert-Butoxy)phosphorylhydroxymethyl]-D,L-phenylalanine

Participants

Reaction Steps

A solution of compound 8 (410 mg, 1.02 mmol) in dioxane (10 mL) is treated with 1 N NaOH (5.1 mL, 5 eq.) and stirred at ambient temperature (0.5 h), yielding a solution of crude 4-[bis(tert-Butoxy)phosphorylhydroxymethyl]-D,L-phenylalanine (15), which is not isolated. The pH is adjusted to 8 by bubbling in CO2 gas, Fmoc-OBT (402 mg, 1.12 mmol) is added and the mixture stirred at ambient temperature (3.5 hours). Ice-cold 5% citric acid (25 mL) is added and the resultant solution is extracted with CHCl3 (3×30 mL). The combined extracts are dried (MgSO4) and evaporated under reduced pressure to yield crude 16. Purification by silica gel chromatography affords pure 16 as a colorless foam (277 mg, 44%).

Provenance & Evidence