Tert-butyl pyrocarbonate

The submitters used commercially available tert-butyl pyrocarbonate from either Fluka or Aldrich Chemical Company, Inc. Alternatively, the reagent can be prepared according to Pope, B. M. Yamamoto, Y. Tarbell, D. S. Org. Synth., Coll. Vol. W1988, 418. 

This material Is pure enough for use in the next step. The impurities of tert-butyl alcohol and a small amount of unreacted tert-butyl pyrocarbonate do not interfere with the oxidation. 

Di-tert-butyl pyrocarbonate Formic acid, oxydi-, di-tert-butyl ester (8) Dicarbonic acid, bis(1,1-dimethylethyl) ester (9) (24424-99-5)... 

More recently tert.butyl pyrocarbonate, usually described as tert.butyl carbonic anhydride, gained considerable popularity, mainly because the products formed during introduction of the Boc group, are harmless and easily removed ... 

Di-tert-butyl dicarbonate (or tert-butyl pyrocarbonate) t-Boc20 is an excellent reagent for the preparation of f-Boc-deriv-atives, N-silylmethylamines 128—132 (Table 24.6) (53,79). The stirring of a solution of (phthalimidomethyldimethylsilanyl) alkanols and hydrazine hydrate in absolute ethyl alcohol leads to the formation of aminomethyldimethylsilyl alcohols (53). Their purification on a chromatography column (silica gel) results in numerous degradation products. The protection of their amino groups with di-tert-butyl dicarbonate at room temperature affords more stable t-Boc-derivatives N-silylmethylamines 128-131 (Scheme 24.16). 

If crude material containing tert-butyl alcohol and unreacted pyrocarbonate is used in this step, the amount of starting material present is calculated based on the mass balance for the first step, assuming a quantitative conversion, and 1.05 equivalents of lead tetraacetate are used. The checkers used only pure material and advise against carrying forward less pure carbamate. 

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