870-50-8

Purification Methods

The tert-butyl ester has the advantage over the ethyl ester (below) in being a solid and more acid labile. It crystallises from ligroin and is best purified by covering the dry solid (22g) with pet ether (b 30-60o, 35-40 mL) heating to boiling and adding ligroin (b 60-90o) until the solid dissolves. On cooling, large lemon yellow crystals of the ester separate (~ 20g), m 90.7-92o. Evaporation of the filtrate gives a further crop of crystals [Carpino & Crowley Org Synth 44 18 1964]. This reagent is useful in the Mitsunobu reaction [Mitsunobu Synthesis 1 1981, Gennari et al. J Am Chem Soc 108 6394 1986, Evans et al. J Am Chem Soc 108 6394 1986, Hughes Org React 42 335 1992, Dodge et al. Org Synth 73 110 1996, Hughes Org Prep Proc Int 28 127 1996, Ferguson & Marcelle J Am Chem Soc 128 4576 2006, see also DEAD and DIAD below].

General Description

Di-tert-Butyl azodicarboxylate (DBAD) is a key reagent used in Mitsunobu reactions, where it acts as an oxidizing agent alongside triphenylphosphine to facilitate the conversion of alcohols into esters or other functional groups. It is also employed in copper-catalyzed tandem oxidation-olefination processes, demonstrating its versatility in organic synthesis for constructing complex molecules under mild, environmentally friendly conditions. Its role in these reactions highlights its importance in facilitating selective transformations, such as the synthesis of sulfoxides, sulfones, and alkenes, while maintaining compatibility with various functional groups.