Synthesis of acyl azides and related compounds
Various carboxylic acids were converted into acyl azides in excellent yields in the presence of trichloroacetonitrile, triphenylphosphine and sodium azide at room temperature. The reaction allows the preparation of dipeptides without deprotection or rearrangement during the reaction.
J.-G. Kim, D. O. Jang, Synlett, 2008, 2072-2074.
A general synthesis of acyl azides from the corresponding N-acyl benzotriazoles affords acyl azides in good yields and avoids the use of acid activators and NO+ equivalents typically employed to synthesize these compounds from acid chlorides and hydrazides, respectively.
A. R. Katritzky, K. Widyan, K. Kirichenko, J. Org. Chem., 2007, 72, 5802-5804.
Amides react with NaN3 to give acyl azides in DMF at 25°C and produce symmetrical ureas in THF/H2O at 80 °C via a sequential acyl substitution and Curtius rearrangement. All acyl azides were also obtained from secondary amides via sequential reaction with p-toluenesulfonyl chloride and NaN3. In addition, keto-stabilized iminophosphoranes can also be prepared in a one-pot reaction.
D. Joseph, S. Lee, Org. Lett., 2022, 24, 6186-6191.
A N-heterocyclic carbene catalyzes the oxidative esterification of various aldehydes in the presence of 3,3',5'5-tetra-tert-butyldiphenoquinone to yield hexafluoroisopropylesters, which are useful active esters for in situ amide bond formation. This transition metal-free organocatalytic system also enabled a mild oxidative azidation of aldehydes.
S. De Sarkar, A. Studer, Org. Lett., 2010, 12, 1992-1995.
Various aliphatic and aromatic aldehydes are converted into their corresponding carbamoyl azides in very good yields in the presence of iodobenzene dichloride and sodium azide in acetonitrile under nitrogen.
X.-Q. Li, X.-F. Zhao, C. Zhang, Synthesis, 2008, 2589-2593.
Aliphatic and aromatic aldehydes can be converted to acyl azides by treatment with iodine azide. If the reaction is performed at reflux, Curtius rearrangement occurs and carbamoyl azides are obtained directly from the aldehyde in good yield.
L. Marinescu, J. Thinggaard, I. B. Thomsen, M. Bols, J. Org. Chem., 2003, 68, 9453-9455.
Aldehydes are safely and conveniently converted to acyl azides and benzyl ethers to azido ethers by treatment with polymer supported iodine azide in MeCN at 83 °C. The reaction provides an alternative to the use of iodine azide in radical azidonations.
L. G. Marinescu, C. M. Pedersen, M. Bols, Tetrahedron, 2005, 61, 123-127.