Ethyl diazoacetate → (2-Bocamino-2-methyl-propoxy)-acetic acid

Participants

Reaction Steps

##STR194## A solution of 2-t-butoxycarbonylamino-2-methylpropanol (5.0 g, 26.46 mmol) and rhodium(II)acetate (90 mg) in dichloroethane (500 ml) was heated to 80° C. Then ethyl diazoacetate (4.0 g, 34.78 mmol) was added over a period of 1 h and the mixture was stirred at reflux for 3 h. Another portion of rhodium(II)acetate (90 mg) was added and the mixture was refluxed for another 5 h. The mixture was cooled overnight and saturated sodium bicarbonate (500 ml) was added, the layers were separated and the organic layer was washed twice with saturated sodium bicarbonate (2×200 ml) and dried (magnesium sulfate) and concentrated in vacuo. The obtained product was dissolved in 1M lithium hydroxide in methanol/water 3:1 (200 ml) and stirred overnight. The solvent was removed in vacuo to a minimum, water (50 ml) was added (pH >9) and the mixture was washed with ether (100 ml). Then 1M hydrochloric acid was added until pH <4 and the mixture was extracted with ethyl acetate (100 ml) and the combined organic layers were dried (magnesium sulfate) and concentrated in vacuo to give 2.5 g of (2-t-butoxycarbonylamino-2-methylpropoxy) acetic acid.

Provenance & Evidence