2-(tert-Butoxycarbonyloxyimino)-2-phenylacetonitrile

White to off-white microcrystalline powder

Widely used for protection of amino groups in peptide synthesis and multi-step organic synthesis of small molecules.

Organic Syntheses, Coll. Vol. 6, p. 199, 1988
Tetrahedron Letters, 16, p. 4393, 1975 DOI: 10.1016/S0040-4039(00)91133-X

Triturate the solid with 90% aqueous MeOH, filter, wash with 90% aqueous MeOH and dry it in a vacuum. Recrystallise it from MeOH (needles or plates), but use warm MeOH and cool to crystallise; do not boil as it decomposes slowly. IR has max 1785 (C=O) cm-1 and NMR (CDCl3) usually shows two tert-butyl singlets for syn and anti isomers. Store it in a brown bottle (fridge). It evolves CO2 at room temperature (stoppered bottle can explode!), but can be stored over silica gel which may extend its useful life to more than a year. [Itoh et al. Org Synth 59 95 1980.]