Synthesis of α-Amino Acids and Derivatives
A nucleophilic acid-free addition of dicyanomethyl acetate to N-methylaldimines gives α-(N-methyl-N-acetyl)amino acid methyl esters in excellent yield.
H. Nemoto, T. Kawamura, N. Miyoshi, J. Am. Chem. Soc., 2005, 127, 14546-14547.
Direct electrocarboxylation of various N-acylimines with atmospheric CO2 is achieved in an undivided cell under mild conditions, affording substituted α-amino acids in good yields. The reaction can be conducted with high efficiency using triethanolamine as an external reductant under nonsacrificial anode conditions.
K. Zhang, X.-F. Liu, W.-Z. Zhang, W.-M. Ren, X.-B. Lu, Org. Lett., 2022, 24, 3566-3569.
Easily available, bench-stable 4-amido Hantzsch ester derivatives serve as precursors to carbamoyl radicals that undergo rapid addition to N-aryl imines. This operationally simple reaction proceeds under blue light irradiation in the presence of the photocatalyst 3DPAFIPN and Brønsted/Lewis acid additives.
L. Cardinale, M.-O. W. S. Schmotz, M. O. Konev, A. J. von Wangelin, Org. Lett., 2022, 24, 506-510.
Bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) (FIrpic) is an effective catalyst of a visible-light photoredox reaction of N,N-dimethylaniline derivatives and aryl isocyanates or aryl isothiocyanates to yield α-amino amides or α-amino thioamides. The reaction involves generation of α-aminoalkyl radicals from tertiary amines, followed by radical addition to the electron-deficient carbon of the isocyanates or isothiocyanates.
H. Zhou, P. Lu, X. Gu, P. Li, Org. Lett., 2013, 15, 5646-4649.
The addition of carbamoyl anions derived from N,N-disubstituted formamides and LDA to N-tert-butyl nitrones provided a direct route to α-(N-hydroxy)amino amides. Derivatization of the products by tert-butyl deprotection or N-deoxygenation was demonstrated.
J. T. Reeves, C. Lorenc, K. Camara, Z. Li, H. Lee, C. A. Busacca, C. H. Senanayake, J. Org. Chem., 2014, 79, 5895-5902.
In the presence of oxygen and a small amount of AIBN as radical initiator, primary amines are oxidatively coupled to imines and tertiary amines are cyanated to α-aminonitriles. These metal-free aerobic oxidative coupling reactions may find applications in a wide range of green oxidation chemistry.
L. Liu, Z. Wang, X. Fu, C.-H. Yan, Org. Lett., 2012, 14, 5692-5695.
A diastereoselective addition of carbamoyl anions to azirines affords synthetically useful 2-aziridinyl amide building blocks. A one-pot conversion of a ketoxime to an aziridinyl amide was also demonstrated.
M. J. Kerner, C. A. Kuttruff, M. Chevliakov, F. G. Buono, D. A. Gao, M. Krawiec, C. A. Busacca, C. H. Senanayake, P. Wipf, J. T. Reeves, Org. Lett., 2021, 23, 4396-4399.