Alternative to 'DEAD' (Diethyl- azodicarboxyl-ate, L19348), more stable at elevated temperatures. DIAD has been used in combination with Triphenyl-phosphine, in Mitsunobu-type reactions of alcohols with acids, amides, etc. In the Mitsunobu esterification reaction yields improve with increasing acid strength. For a discussion, see: J. Org. Chem., 61, 2967 (1996). For use in the regioselective, stereospecific Mitsunobu azidation of 1,2- and 1,3-diols with Trimethyl-silyl- azide, see: J. Org. Chem., 64, 6049 (1999). An extremely mild route to isocyanates involves treatment of an aliphtic primary amine with CO2 to form the carbamate salt which reacts at low temperature with the Mitsunobu reagent from DIAD and PPh3, giving the isocyanate in high yield. 2,6-Dialkylanilines also undergo the reaction if Bu3P is used; the reaction failed with other anilines: Tetrahedron Lett., 40, 363 (1999). For reviews of the Mitsunobu reaction, see: Synthesis, 1 (1981); Org. React., 42, 335 (1992); Org. Prep. Proced. Int., 28, 127 (1996). For a brief feature on synthetic uses of Mitsunobu reagents, see: Synlett, 1221 (2003).
