Synthesis of α-azidoketones, α-azidoacids and related compounds
Chiral tertiary α-hydroxy esters were transformed to α-azido esters by Mitsunobu reaction with HN3. Reactions proceed at room temperature with high chemical yield using 1,1-(azodicarbonyl)dipiperidine (ADDP) and trimethylphosphine (PMe3) with complete inversion of configuration at the α-carbon. Several α,α-disubstituted amino acids were synthesized in high overall chemical yield and optical purity.
J. E. Green, D. M. Bender, S. Jackson, M. J. O'Donnell, J. R. McCarthy, Org. Lett., 2009, 11, 807-810.
A metal-free azide insertion of α-aryl α-diazoesters in the presence of B(C6F5)3 as catalyst affords the corresponding products in good yields. The reaction offers easy operation, wide substrate scope, and mild conditions and tolerates alkene and alkyne functional groups without cyclopropanation or cyclopropenation side products. A one-pot synthesis of 1,2,3-triazoles is also described.
H. H. San, C.-Y. Wang, H.-P. Zeng, S.-T. Fu, M. Jiang, X.-Y. Tang, J. Org. Chem., 2019, 84, 4478-4485.
An iron-catalyzed radical alkylazidation of electron-deficient alkenes with trimethylsilyl azide and alkyl diacyl peroxides as the alkyl source provides a range of α-azido esters, an α-azido ketone, and an α-azido cyanide in high yields. This method features mild reaction conditions, wide substrate scope, and good functional group tolerance.
R. Wei, H. Xiong, C. Ye, Y. Li, H. Bao, Org. Lett., 2020, 22, 3195-3199.
A recoverable chiral quaternary salt as catalyst enables phase transfer, ion-pair mediated reactions of racemic α-bromo ketones to chiral α-azido and α-amino ketones with high enantioselectivity in fluorobenzene-water. The process has been generalized to various other replacements of bromine.
R. da Silva Gomes, E. J. Corey, J. Am. Chem. Soc., 2019, 141, 20058-20061.
A mild and rapid formal electrophilic α-azidation of 1,3-dicarbonyl compounds using commercially available Bu4NN3 as the azide source is mediated by (diacetoxyiodo)benzene. The reaction conditions are Bäcklund to the ones employed in analogous halogenations with Et4NX (X = Cl, Br, I).
M. J. Galligan, R. Akula, H. Ibrahim, Org. Lett., 2014, 16, 600-603.
The reaction of 1,3-dicarbonyl compounds with molecular iodine and sodium azide in aqueous DMSO provides a general access to a broad range of geminal diazides with various structural motifs including sterically demanding substituents and ordinary functional groups. The diazidation of 1,3-dicarbonyls can be selectively achieved even in the presence of other 1,3-dicarbonyls with substituents at 2-position.
H. Erhardt, A. P. Häring, A. Kotthaus, M. Roggel, M. L. Tong, P. Biallas, M. Jübermann, F. Mohr, S. F. Kirsch, J. Org. Chem., 2015, 80, 12462-12469.